SLP215 Michael Flaxman – 10x Your Bitcoin Security With ...

r/bitcoin HODL deceit

bitcoin HODL deceit submitted by userforlessthan2mins to btc [link] [comments]

Avalanche protocol status?

Hi, I think the real holy grail of any crypto is the instant confirmation to enable fast payment both in real world and online. My understanding is that Avalanche offer a pretty fast (couple second) to get a consensus. I would like to know more about it, especial the status. Who is working on it, is there is major road block, any ETA?
Thanks!
submitted by Zyoman to btc [link] [comments]

Just made my first 0-conf transaction with Bitcoin Cash!

And boy does it feels good knowing that Bitcoin Cash does not have RBF and all tx will make it into the next block.
submitted by aggressive_simon to btc [link] [comments]

Double spend proof just got real, a first implementation of proof-of-concept now exists as pull request to Flowee the Hub

In Bitcoin Cash the miners and nodes use a 'first seen' principle of receiving transactions, which means that accepting unconfirmed transactions (aka instant transactions) is generally speaking safe as any double spend will be rejected by the entire network.
But when we actively try to attack a merchant, there still are cases where the double spend can be the one mined. And here is the important part, vendors never get notified of that person in their store trying to double spend. The problem then is that an attacker may try to double spend a merchant with no detection if he fails, until he succeeds...
The solution we came up with is double-spend-proofs. A relatively small (constant size) message with actual proof that the spender signed two different transactions spending the money you were hoping to receive. An important part of this work was to make sure the original double spending transaction can not be reconstructed. So we don't make it easier for the double spend to propagate.
Double spend proofs have been an idea for years, with lots of people talking about it and we had some initial specs and even a conference about this last year.
So, the last weeks I sat down and actually did the design work and wrote the core code on how this is supposed to work as part of the Flowee central Hub. You can see the pull request here and the spec is in progress here. Though naturally the spec will only be made useful after a successful test of the implementation has finished.
edit; direct link to spec; https://github.com/imaginaryusername/specs_n_stuff/blob/mastedsproof/dsproof.md

Who benefits?

The idea of a double spend proof is to inform people receiving funds. The design allows both full nodes and SPV wallets to receive this message and it can be cryptographically checked to make sure that the double spend proof is legit (people can't lie about someone else double spending funds).
The main point is that we don't expect miners to change what they mine based on this message (Avalanche can do that), this is purely to inform people receiving money that the payer tried to cheat them. And provide actual proof that justice could use to prosecute this person.
The point, therefor, is not to avoid the stealing, the point is to inform and protect the merchants. And thus lower the risk of accepting instant-transactions.
ps. this will not work on BTC, as we improved the signing method in BCH.
submitted by ThomasZander to btc [link] [comments]

What are some Problems with Bitcoin?

Bitcoin is a revolutionary technology that is already changing the world — but it is not perfect. Most notable are its ease-of-use issues that may make mainstream adoption difficult, if not impossible. Listed below are some of the existing faults with Bitcoin and its practical usage.
submitted by Boomah422 to bitcointhetrilema [link] [comments]

Which type of curren(t) do you want to see(cy)? A analysis of the intention behind bitcoin(s). [Part 2]

Part 1
It's been a bit of time since the first post during which I believe things have crystallised further as to the intentions of the three primary bitcoin variants. I was going to go on a long winded journey to try to weave together the various bits and pieces to let the reader discern from themselves but there's simply too much material that needs to be covered and the effort that it would require is not something that I can invest right now.
Firstly we must define what bitcoin actually is. Many people think of bitcoin as a unit of a digital currency like a dollar in your bank but without a physical substrate. That's kind of correct as a way to explain its likeness to something many people are familiar with but instead it's a bit more nuanced than that. If we look at a wallet from 2011 that has never moved any coins, we can find that there are now multiple "bitcoins" on multiple different blockchains. This post will discuss the main three variants which are Bitcoin Core, Bitcoin Cash and Bitcoin SV. In this respect many people are still hotly debating which is the REAL bitcoin variant and which bitcoins you want to be "investing" in.
The genius of bitcoin was not in defining a class of non physical objects to send around. Why bitcoin was so revolutionary is that it combined cryptography, economics, law, computer science, networking, mathematics, etc. and created a protocol which was basically a rule set to be followed which creates a game of incentives that provides security to a p2p network to prevent double spends. The game theory is extremely important to understand. When a transaction is made on the bitcoin network your wallet essentially generates a string of characters which includes your public cryptographic key, a signature which is derived from the private key:pub key pair, the hash of the previous block and an address derived from a public key of the person you want to send the coins to. Because each transaction includes the hash of the previous block (a hash is something that will always generate the same 64 character string result from EXACTLY the same data inputs) the blocks are literally chained together. Bitcoin and the blockchain are thus defined in the technical white paper which accompanied the release client as a chain of digital signatures.
The miners validate transactions on the network and compete with one another to detect double spends on the network. If a miner finds the correct solution to the current block (and in doing so is the one who writes all the transactions that have elapsed since the last block was found, in to the next block) says that a transaction is confirmed but then the rest of the network disagree that the transactions occurred in the order that this miner says (for double spends), then the network will reject the version of the blockchain that that miner is working on. In that respect the miners are incentivised to check each other's work and ensure the majority are working on the correct version of the chain. The miners are thus bound by the game theoretical design of NAKAMOTO CONSENSUS and the ENFORCES of the rule set. It is important to note the term ENFORCER rather than RULE CREATOR as this is defined in the white paper which is a document copyrighted by Satoshi Nakamoto in 2009.

Now if we look at the three primary variants of bitcoin understanding these important defining characteristics of what the bitcoin protocol actually is we can make an argument that the variants that changed some of these defining attributes as no longer being bitcoin rather than trying to argue based off market appraisal which is essentially defining bitcoin as a social media consensus rather than a set in stone rule set.
BITCOIN CORE: On first examination Bitcoin Core appears to be the incumbent bitcoin that many are being lead to believe is the "true" bitcoin and the others are knock off scams. The outward stated rationale behind the bitcoin core variant is that computational resources, bandwidth, storage are scarce and that before increasing the size of each block to allow for more transactions we should be increasing the efficiency with which the data being fed in to a block is stored. In order to achieve this one of the first suggested implementations was a process known as SegWit (segregating the witness data). This means that when you construct a bitcoin transaction, in the header of the tx, instead of the inputs being public key and a signature + Hash + address(to), the signature data is moved outside of header as this can save space within the header and allow more transactions to fill the block. More of the history of the proposal can be read about here (bearing in mind that article is published by the bitcoinmagazine which is founded by ethereum devs Vitalik and Mihai and can't necessarily be trusted to give an unbiased record of events). The idea of a segwit like solution was proposed as early as 2012 by the likes of Greg Maxwell and Luke Dash Jnr and Peter Todd in an apparent effort to "FIX" transaction malleability and enable side chains. Those familiar with the motto "problem reaction solution" may understand here that the problem being presented may not always be an authentic problem and it may actually just be necessary preparation for implementing a desired solution.
The real technical arguments as to whether moving signature data outside of the transaction in the header actually invalidates the definition of bitcoin as being a chain of digital signatures is outside my realm of expertise but instead we can examine the character of the individuals and groups involved in endorsing such a solution. Greg Maxwell is a hard to know individual that has been involved with bitcoin since its very early days but in some articles he portrays himself as portrays himself as one of bitcoins harshest earliest critics. Before that he worked with Mozilla and Wikipedia and a few mentions of him can be found on some old linux sites or such. He has no entry on wikipedia other than a non hyperlinked listing as the CTO of Blockstream. Blockstream was a company founded by Greg Maxwell and Adam Back, but in business registration documents only Adam Back is listed as the business contact but registered by James Murdock as the agent. They received funding from a number of VC firms but also Joi Ito and Reid Hoffman and there are suggestions that MIT media labs and the Digital Currency Initiative. For those paying attention Joi Ito and Reid Hoffman have links to Jeffrey Epstein and his offsider Ghislaine Maxwell.

Ghislaine is the daughter of publishing tycoon and fraudster Robert Maxwell (Ján Ludvík Hyman Binyamin Hoch, a yiddish orthodox czech). It is emerging that the Maxwells are implicated with Mossad and involved in many different psyops throughout the last decades. Greg Maxwell is verified as nullc but a few months ago was outed using sock puppets as another reddit user contrarian__ who also admits to being Jewish in one of his comments as the former. Greg has had a colourful history with his roll as a bitcoin core developer successfully ousting two of the developers put there by Satoshi (Gavin Andreson and Mike Hearn) and being referred to by Andreson as a toxic troll with counterpart Samon Mow. At this point rather than crafting the narrative around Greg, I will provide a few links for the reader to assess on their own time:
  1. https://coinspice.io/news/btc-dev-gregory-maxwell-fake-social-media-account-accusations-nonsense/
  2. https://www.trustnodes.com/2017/06/06/making-gregory-maxwell-bitcoin-core-committer-huge-mistake-says-gavin-andresen
  3. https://www.ccn.com/gavin-andresen-samson-mow-and-greg-maxwell-toxic-trolls//
  4. https://www.nytimes.com/2016/01/17/business/dealbook/the-bitcoin-believer-who-gave-up.html
  5. https://www.coindesk.com/mozilla-accepting-bitcoin-donations
  6. https://spectrum.ieee.org/tech-talk/computing/networks/the-bitcoin-for-is-a-coup
  7. https://www.reddit.com/btc/comments/68pusp/gavin_andresen_on_twitter_im_looking_for_beta/dh1cmfl/
  8. https://www.reddit.com/btc/comments/d14qee/can_someone_post_the_details_of_the_relationships/?ref=tokendaily
  9. https://www.coindesk.com/court-docs-detail-sexual-misconduct-allegations-against-bitcoin-consultant-peter-todd
  10. https://coinspice.io/news/billionaire-jeffrey-epstein-btc-maximalist-bitcoin-is-a-store-of-value-not-a-currency/
  11. https://www.dailymail.co.uk/news/article-7579851/More-300-paedophiles-arrested-worldwide-massive-child-abuse-website-taken-down.html
  12. https://news.bitcoin.com/risks-segregated-witness-opening-door-mining-cartels-undermine-bitcoin-network/
  13. https://micky.com.au/craig-wrights-crackpot-bitcoin-theory-covered-by-uks-financial-times/
  14. https://www.reddit.com/btc/comments/74se80/wikipedia_admins_gregory_maxwell_of_blockstream/

Now I could just go on dumping more and more articles but that doesn't really weave it all together. Essentially it is very well possible that the 'FIX' of bitcoin proposed with SegWit was done by those who are moral reprobates who have been rubbing shoulders money launderers and human traffickers. Gregory Maxwell was removed from wikipedia, worked with Mozilla who donated a quarter of a million to MIT media labs and had relationship with Joi Ito, the company he founded received funding from people associated with Epstein who have demonstrated their poor character and dishonesty and attempted to wage toxic wars against those early bitcoin developers who wished to scale bitcoin as per the white paper and without changing consensus rules or signature structures.
The argument that BTC is bitcoin because the exchanges and the market have chosen is not necessarily a logical supposition when the vast majority of the money that has flown in to inflate the price of BTC comes from a cryptographic USD token that was created by Brock Pierce (Might Ducks child stahollywood pedo scandal Digital Entertainment Network) who attended Jeffrey Epstein's Island for conferences. The group Tether who issues the USDT has been getting nailed by the New York Attorney General office with claims of $1.4 trillion in damages from their dodgey practices. Brock Pierce has since distanced himself from Tether but Blockstream still works closely with them and they are now exploring issuing tether on the ethereum network. Tether lost it's US banking partner in early 2017 before the monstrous run up for bitcoin prices. Afterwards they alleged they had full reserves of USD however, they were never audited and were printing hundreds of millions of dollars of tether each week during peak mania which was used to buy bitcoin (which was then used as collateral to issue more tether against the bitcoin they bought at a value they inflated). Around $30m in USDT is crossing between China to Russia daily and when some of the groups also related to USDT/Tether were raided they found them in possession of hundreds of thousands of dollars worth of counterfeit physical US bills.
Because of all this it then becomes important to reassess the arguments that were made for the implementation of pegged sidechains, segregated witnesses and other second layer solutions. If preventing the bitcoin blockchain from bloating was the main argument for second layer solutions, what was the plan for scaling the data related to the records of transactions that occur on the second layer. You will then need to rely on less robust ways of securing the second layer than Proof Of Work but still have the same amount of data to contend with, unless there was plans all along for second layer solutions to enable records to be deleted /pruned to facilitate money laundering and violation of laws put in place to prevent banking secrecy etc.
There's much more to it as well and I encourage anyone interested to go digging on their own in to this murky cesspit. Although I know very well what sort of stuff Epstein has been up to I have been out of the loop and haven't familiarised myself with everyone involved in his network that is coming to light.
Stay tuned for part 3 which will be an analysis of the shit show that is the Bitcoin Cash variant...
submitted by whipnil to C_S_T [link] [comments]

Hi r/btc. We are launching Atlantis, the easiest way to start accepting BCH 0-conf payments from customers all over the world

When a merchant signs up on our service, he gets access to our API through a dashboard which provides a transaction history of all payments through our service. Some of the features of our service are-
1) Double spend detection - We verify 0-conf payments within 3-5 secs. We detect any double spend attempts and reject those payments. You get to access a bonus feature if you attempt to double spend. :D
2) Secure - We don't act as an intermediary between two parties. The merchant generates an Xpub and we generate new addresses for all payment requests. The merchant gets paid automatically and we have no way to seize/stop/censor any payments
3) Anonymous- Anyone can start accepting funds with a email login and generation of an API key.
4)Easy API- We have tried to develop an API that is very easy for developers to start accepting Bitcoin payments. With this service, developers can work on new ideas which we will let their creative minds come up with.
5)Flat Pricing- Payments no longer get a 2% fee per transaction but a flat monthly subscription fee. You pay at the end of the month and if you choose not to, you can terminate our service. Right now, this is the trial period and there is no fee at all :D
We request users/merchants/developers to sign up and test our service at atlantis. If you know any merchants who want to start accepting Bitcoin for online payments, please direct them to our service.
Our vision is to make global adoption of Bitcoin easier. Peter Thiel says the cost of switching is so high that the benefits should be 10x better. The world around is not going to learn about the disadvantages of paper money and come around to understanding the risk of a 0-conf in Bitcoin. We have to make it 10x easier for them to use Bitcoin. You can find more about our goals and a walkthrough of our product at Atlantis Blog
We would also appreciate any feedback you have for us. We have a few things that are in our immediate pipeline *Multiple Fiat support *Option of importing XPUB
submitted by redditdabbler to btc [link] [comments]

Electroneum Blockchain Upgrade FAQ

FREQUENTLY ASKED QUESTIONS
ELECTRONEUM’S MODERATED BLOCKCHAIN
Q: What is a Moderated Blockchain?
A: Electroneum’s new Moderated Blockchain (a type of permissioned blockchain that is at the qualitative level of IBM’s Hyperledger or Facebook’s announced Libra open ledger network) that has been uniquely and cleverly developed to provide Electroneum with a minimal but sufficient level of interference. This will allow the highly skilled engineering staff to supervise the distributed ledger which is maintained by a list of trusted validators. And this allows the tech team to detect anomalies or irregularities that could come from hackers attempting to breach our security, and immediately stop them preventing a double-spend or 51% attack. Because Electroneum controls the list of trusted validators, this empowers them to guarantee, and that is similar to IBM’s hyper ledger or that of Facebook’s Libra blockchain.
Q: Why did you move to a Moderated Blockchain?
A: To improve the functionality of Electroneum at the exchanges, allowing them to confirm deposit transactions faster and to protect the network from 51% attacks, and also Electroneum can decide to where the block rewards are rerouted ensuring that they are used to help improve the lives of the poorer in underdeveloped countries.
Q: What is the role of blockchain in a permissioned network?
A: It is essentially an immutable history of financial transactions. Electroneum’s Moderated Blockchain, which is a type of permissioned blockchain, unlike other decentralised cryptocurrency networks, can guarantee a tamper-proof system of transactional records.
Q: What motivation would someone have to trade on a permissioned blockchain when their transaction could get rolled back, or worse still, never get confirmed?
A: With Electroneum’s new Moderated Blockchain reorganisations can still occur but never will an irregular transaction actually be fully confirmed and then overwritten.
Q: Is there any risk of manipulation with a moderated blockchain?
A: There is a risk of manipulation if an authenticator key is leaked. However, the extent would be negligible and therefore not affect users, exchanges or miners. We developed a system to closely monitor the behaviour of both the network and miners to ensure any foul play is immediately crushed.
Q: How is Electroneum’s Moderated Blockchain different to other decentralised blockchains?
A: We have the authority to decide who mines the blocks and therefore, we can increase the likelihood that they are trusted validators.
Q: Why doesn’t Electroneum move to a fully centralised blockchain?
A: Our unique and cleverly created Moderated Blockchain is meant to have minimal interference to remove the risks and add protection whilst remaining decentralised to the point wherein the unlikely event that a meteor was to wipe out all of the Electroneum staff out of the face of the Earth by a meteor, ETN would not cease to exist. This because those nodes currently mining our blockchain or anybody else for that fact could swap out the codes and fork the network to take over control and guarantee the permanence of the cryptocurrency thus shielding our users from losses.
Q: What is Proof of Responsibility or PoR?
A: Proof of Responsibility, or PoR for short, is a new mining paradigm which obligates the miners to two primary responsibilities which are: 1) Maintain the integrity of the payment network, and 2) Spend the block rewards they receive responsibly to help poor people in line with Electroneum’s humanitarian agenda.
Q: How does PoR compare to PoW or Proof of Work?
A: PoR saves a lot of time and energy compared to PoW because instead of working with block validators overtime to prove or not that they’re reliable miners, we save time and potential adverse issues by hand-picking the miners ourselves.
SECURITY AND 51% ATTACKS OR DOUBLE SPENDS
Q: What is a 51% attack?
A: It is when someone takes over 50% control of the hashing power of a cryptocurrency. Hackers usually use this to benefit themselves with double spends, which is a hard loss for the exchanges as well as users in many cases.
Q: What IS an example of a 51% attack?
A: You may know 51% attacks better from both Bitcoin Cash in 2018 and Ethereum Classic in 2019, where hackers acquired more than 50 percent of the hashing power on those networks and getting away with a significant loot.
Q: What is hashing power?
A: This is the rate with which the mining rigs solve mathematical problems.
Q: Why doesn’t Electroneum require large amounts of hashing power anymore?
A: The Electroneum network difficulty automatically adjusts to maintain the target block time of two minutes. Regardless of the magnitude of the hashing power in Electroneum’s network will be kept to a two-minute target block time.
Q: Is Electroneum now insusceptible to a 51% attack?
A: We’re no longer susceptible to a 51% attack – making us one of the most secure blockchains in existence today.
Q: What if someone hack one authenticated miner?
A: In the unlikely event that hackers were to succeed in breaching the security of an authenticated miner, the authentication key of that miner would not be accessible to the hacker in itself because of the unique way our blockchain team has come up to shield it from being discovered. The hacker, therefore, would not be able to affect the network because they would be unable to mine sequential blocks. And because of the uniqueness of the Moderated Blockchain, our moderating network layer would immediately detect the breach and rescind the rights of that miner.
Q: What if two or more hacks?
A: If one hack is highly unlikely due to two security breaches being necessary, two hacks are exponentially harder to achieve. But if it were to happen, the keys they may have stolen limit the hash rate of the miner. This means that if somebody were to take the code and run it on the highest-powered mining machine, it would still produce the same hash rate as it would in the lowest powered mining rig making it impossible for them to control over 50% of the network’s hash rate because of the way our Moderated Blockchain is set up. This also ensures the NGOs can run an Electroneum mining node on hardware with which their tech teams are familiar.
Q: How do you judge how responsible the miners are?
A: We look at how many blocks they are mining compared to how many blocks they are expected to mine going by the hashing power allotted to them.
Q: What happens after a mining node has been shut off?
A: Simply, it stops mining and needs to be restarted and then retype or re-enter the authentication key.
NEW TRUSTED MINERS
Q: Who are the miners?
A: We have chosen vocational NGOs as trusted mining partners who are also trustworthy organisations. We have done due diligence to ensure they are transparent, honest, and aligned with our vision to work within the developing world. We have made sure that they also want to accompany us in our goal to expand our Gig Fair project, which is aimed at helping provide people in the poorest regions of the world with an income opportunity and the opportunity to attain skills and means to generate an income that will empower them to live better. The NGOs that we’ve selected are trusted brands that have proven track records in helping people. Cryptocurrency is at its early stages and is met with skepticism by many people and entities around the world as well as in the developing world. So, our mission is to educate these NGOs about cryptocurrency so that they can, in turn, convey the message of the benefits of crypto, particularly ETN, to people in the developing world and make them feel more confident to use crypto, which ultimately will help spur crypto’s mass adoption.
Q: Why are these NGOs anonymous (initially)?
A: Because they themselves have decided to remain anonymous over concerns of how cryptocurrency could reflect on their organisations.
Q: What do NGOs do for the project?
A: They validate the blocks and rewarded for this and take the proceeds to help people?
Q: Where are the NGO’s and Charities located?
A: For now, locations of the NGOs are being kept undisclosed for security reasons until they themselves decide they if they want to make public that information.
Q: Five million ETN or about $22,500 at the then valuation was paid out daily before. How much is being paid out now?
A: Because the block rewards have been reduced by a whopping 75% creating scarcity which is a good thing to extend longevity, currently just over 1.2 million ETN or about $5,300 is being paid out in block rewards.
Q: Can we see who is mining and how much they are mining?
A: The block rewards will still be visible on the blockchain explorer and those with sufficient technical knowledge will be able to see the different miners signing blocks with different mining keys. But Electroneum is not forcing the NGOs to reveal their identities because they are still going through a learning curve and when they understand crypto and experience the benefits first-hand, they will more than likely reveal themselves.
Q: Where are their mining rigs stored?
A: We have suggested that mining rigs be run in the cloud to ensure uptime; however, ultimately, it is up to the NGOs themselves decide where their equipment is hosted. It is essential to point out that we have reduced energy and hash rates by a millionfold as such a standard rack-mounted server that you would find in any business today is sufficient to run an Electroneum mining node.
Q: Who setup their mining rigs?
A: At this stage, all mining rigs have been set up by the Electroneum team as this is the first foray for NGOs into the cryptocurrency mining space.
Q: Who is managing their mining rigs?
A: The mining rigs are self-sufficient and need very little if any, technical support, however, a moderator layer monitors the new Moderated Blockchain to ensure the mining rigs are online and benefit the network. If we were to detect a mining rig going offline, we would inform the NGO and provide assistance where required.
Q: How will NGOs use their ETN (from mining blocks)?
A: The NGOs, initially, almost certainly convert the ETN to USD or other currencies because they have always used fiat to deliver their donations and assistance because that is what they are used to doing. Once they see the benefits and value of ETN they may start using it on the ground to amongst the people they help. We have deliberately targeted NGOs that are in regions that were we are imminent to enable airtime top-ups directly with ETN from within the Electroneum mobile app.
FUTURE PROGRESS & CORPORATE PARTNERSHIPS
Q: How will this initiative affect corporate partnerships moving forward?
A: Because the network is more secure, Electroneum as a platform will be more attractive as a platform in the eyes of potential partners.
Q: How will it help to grow our on-the-ground initiatives?
A: The NGO’s we’re working with will be in the regions we’re targeting on the ground. So, this will be contributing to the eco-system, the NGO’s will be able to spend their ETN on education through the Gig Economy too.
Q: Can new NGOs apply to mine?
A: I If you know or are an NGO that focuses on vocational training and education, and that it is within the developing world, then we would love to hear from you via our community forum.
Q: How will the 75% reduction in the block reward benefit the community?
A: Reducing the block rewards means ETN ‘s expands the longevity of the coin by making ETN scarcer and thus lengthening the duration of the emission of coins.
submitted by xterest27 to Electroneum [link] [comments]

Why the Lightning Network is not a "Scaling Solution"

It’s honestly a little bizarre to see people still pushing the idea that the Lightning Network is a “scaling solution” for Bitcoin. It seems to me that the key observation in understanding why this is not the case is the recognition that the Lightning Network is a necessarily-imperfect money substitute for on-chain transactions, and moreover, that it becomes an even more imperfect substitute the more the blockchain it is operating on top of is constrained.
The Lightning Network Necessarily Defines a More Limited Payment Possibilities Graph
With on-chain transactions, the graph of possible payments is essentially a complete graph. Anyone who holds bitcoin can pay anyone else any amount up to all of the money the payer holds. And the possible recipients in this case don’t even need to be already “in the network.” Anyone who can generate and provide a valid payment address can receive payment.
In contrast, with the Lightning Network, anyone who is connected to the Lightning Network can pay anyone else who is also connected to the Lightning Network, and to whom a route exists and can be found, an amount that is limited by the hop in the route having the smallest available liquidity in the required direction. (If multiple routes exist and can be found, and don’t share the same limiting hop, the maximum possible payment can be increased accordingly, but the same general limiting principle applies.)
The Lightning Network Is Necessarily Less Secure - Part 1
The security model of an on-chain transaction is based on the fact that double spending a confirmed transaction “quickly becomes computationally impractical for an attacker” if a majority of the hash rate is honest. Thus, confirmed payments grow more secure over time—and very quickly become “irreversible” for practical purposes—as additional confirmations are received. Protecting funds received via such payments does not require any active monitoring or continued connection to the network.
In contrast, the security model of the Lightning Network requires eternal vigilance (that this vigilance can be outsourced to proposed “watch towers” does not change this problem, but merely moves it). If a channel partner broadcasts an old channel state in an attempt to steal funds from you, you must detect the attempted theft and act to block it in a timely manner by getting your own “breach remedy transaction” added to the blockchain within a defined “dispute period.” That is a fundamentally different (and weaker) security model. It depends on a user’s supposed ability to, when needed, get an on-chain transaction confirmed on the blockchain in a timely manner, which is, of course, exactly what’s compromised by an artificial constraint on on-chain capacity. This is the first way in which the LN becomes a more imperfect substitute the more the base blockchain is constrained, and is what I refer to as the LN’s “fractional-teller banking” problem.
It’s also worth noting that an individual’s inadvertent broadcasting of an out-of-date channel state (e.g., due to a faulty node backup) can result in their losing all of their funds in the channel. This represents a second risk vector that is not present with on-chain payments. A closely-related problem is the fact that funds in a LN wallet, unlike funds in a regular wallet, cannot be backed up statically (e.g., with a 12-word seed). Instead, a new backup must be created and securely stored every time any of your "channel state" information changes. This occurs every time you send a LN payment, every time you receive a LN payment, and every time someone else's payment is routed through one of your channels.
The Lightning Network Is Necessarily Less Secure - Part 2
If a channel partner becomes uncooperative, you will be forced to close that channel via a unilateral close, in which case your funds will be effectively frozen until the end of the dispute period. That’s a form of counterparty risk that simply does not exist with funds that are held on-chain.
The Lightning Network Has a Natural Tendency to Centralize That is Exacerbated by a Constrained Base Blockchain
It’s important to keep in mind that the Lightning Network is not a piece of software. It’s a network that grows and changes as people open channels, route payments through those channels (thereby changing their liquidity states), and close channels. There is of course a cost to opening a channel. This cost includes the cost of the requisite on-chain transaction as well as an opportunity cost, i.e., funds committed to one channel can’t simultaneously be used to fund another channel with someone else. There is also a cost associated with the risk that a particular channel will not prove useful, leading to its closure in the future and thereby necessitating a second on-chain transaction fee. On the other hand, the primary benefit of opening a channel is the possible future payments it will allow you to send and receive. The greatest benefit in these terms is provided by a well-funded (on both sides) channel connection to a channel partner who has a huge number of other well-funded channel connections (i.e., a “hub”). Of course, becoming such a “hub” will require massive capitalization to fund all of these channels. There’s also a positive feedback loop / network effect aspect to hub formation. As an emerging hub grows more connected, it becomes an even more desirable channel partner, encouraging even more connections, making it an even more desirable channel partner, etc., etc. A constrained base blockchain amplifies this naturally-centralizing dynamic by greatly increasing the cost of opening and closing channels. If, for example, it costs $50 every time someone goes to open (or close) a channel, individuals will have a strong incentive to be very reluctant to open channels with any nodes other than those who can provide the most benefit (i.e., massively-capitalized, massively-connected hubs). It’s interesting to consider that while the naturally-emergent topology of the Lightning Network is one of massive centralization, the naturally-emergent topology of the Bitcoin mining network is the exact opposite, i.e., a near-complete graph with all miners connected to all or nearly-all others. It’s thus incredibly ironic that those attempting to move us toward the former and away from the latter have attempted to justify their actions with appeals to protecting “decentralization.”
If the Lightning Network Were a Perfect Substitute, That Would Paradoxically Represent a Very Dangerous Situation
For at the least the reasons outlined above, the Lightning Network is not a perfect substitute for the blockchain. But the counterfactual is worth considering. If it were somehow the case that there were no downside to making a particular payment via the Lightning Network, that would paradoxically represent a very dangerous state of affairs. As the block subsidy is phased out, Bitcoin’s security will increasingly need to be paid for via transaction fees. If everyone could get all of the benefit of an on-blockchain transaction without actually using the blockchain and paying those transaction fees (or rather, if they could get all of those benefits by using the blockchain once to open a LN channel they kept open forever), that would create a tragedy of the commons.
Conclusion
Contrary to the claims of many of its proponents, the Lightning Network does not represent “trustless scaling.” At best, it promises a kind of “reduced-trust banking.” While the LN is obviously not traditional, fully-custodial banking (you put the coins in the bank’s vault and only they hold the key), more critically, neither is it the “be your own bank” of Bitcoin proper (the coins are in your own vault and only you hold the key). It’s essentially a hybrid model--which we might call “semi-custodial banking”--in which you and your “bank” (i.e., hub) both lend funds to an entity (the channel) over which control is shared. It’s an interesting idea, and one that might even prove to be useful one day. But it simply cannot eliminate the need for actual (i.e., on-chain) scaling. There will always be a natural balance between money proper (in Bitcoin’s case, on-chain transactions) and various money substitutes. The problem with an arbitrary limit on the capacity of the former is that it distorts this balance.
submitted by Capt_Roger_Murdock to btc [link] [comments]

Avalanche for preventing/mitigating double-spends seems like a gross exercise in over-engineering, all that is needed is for merchants to detect "dubious" Txs, reject them and refund automatically

I've been watching the discussion about using Avalanche for finalizing Txs with great interest, it seemed like a pretty good idea at first but when all the details of making sure that it works as it should are fleshed out, it became apparent it's opening a whole another can of worms that appears to introduce multitude of new problems and complexity instead, to solve just this single problem. And if we end up having dozens other problems and edge cases to "solve" a single problem, is the "solution" really worth it? Especially when there are other, extremely simple, solutions that are just good enough?
In my view the double spend problem can be summarized as such:
This leads me to believe that the following strategy would be sufficient to secure Bitcoin payments to a good enough degree (understand better than any other payment system in existence):
This strategy needs only the development of DS proofs (well under way AFAIK) and DSV collateral DS protection (concept already described) and most importantly changes NOTHING for the honest users
Compare this with making sure Avalanche is:
So in closing, Avalanche seems like a very complex suite of solutions and new issues, all to solve essentially easily mitigated problem of DS that wasn't even demonstrated to be a problem in the wild with the simple mitigations already devised. I believe DS proofs and DSV forfeits should be implemented first to even consider something like Avalanche and until then, it should remain a research project that is not seriously considered to be implemented.
submitted by mushner to btc [link] [comments]

Bitcoin ABC's "parked blocks" feature allows minority hashrate attackers to cause a permanent chain split with high probability.

BACKGROUND
------------------------------------------------------
In November, Bitcoin ABC introduced "auto-finalization" and "parked blocks" functionality in order to mitigate the risk of 51% attacks.
Roughly, the way auto-finalization works is that after receiving a new block, a node will look back ten blocks prior and mark that previous block as finalized, which means that the node will not reorg past that point without manual intervention. This prevents attackers from double spending with large reorgs, and thus provides some protection for exchanges and the like.
The parked blocks functionality is intended to prevent against medium-length reorgs by adding a proof of work penalty. Specifically, a 4+ block reorg requires double the PoW; a 1 or 2 block reorg requires an extra 1/2 blocks' worth of PoW, and a 3 block reorg requires an extra blocks' worth of PoW. These are approximations, because of BCH's DAA which changes each block, but you can find this implemented in FindMostWorkChain() in validation.cpp.
When these changes were added, there was some discussion on btc about how auto-finalization could lead to chain splits because an attacker could mine a 10 block secret chain and broadcast it right at the perfect time that the honest network has broadcast its 10th block from the fork point; however, this is a difficult attack to pull off, and the parked blocks functionality actually makes it such that the attacker would need to mine more like 20 blocks secretly (approximately, because of the DAA), which makes it nearly impossible.
However, I did not see significant discussion regarding the implications of the parked block functionality itself, and the negative way in which it interacts with auto-finalization. Here is my attempt to rectify that, by presenting an attack that could cause chain splits with moderate probability even for attackers with minority hash rate.

ATTACK:
----------------------------------------------------
1) Somehow force a soft-split with the parked chain.
2) Make sure that the soft split continues until both sides finalize a block on their side of the split (possibly via balancing hashpower on both sides of the soft split).
More specifically:
1) Mine 3 blocks before the honest network mines three blocks, and broadcast block 3 when you detect honest block 3 has been broadcast.
2) Mine such that the difficulty/work condition is fulfilled (see step 2 below regarding lowering the difficulty): block1 + 1/2*priv2 + 1/2*pub2 > pub4 + priv4. If this condition isn't met, the attacker can just try to win the split from the next step and get 3-4 block rewards
3) Ensure that each side of the soft split mines block 4 before the other side mines block 5, moving into the double-PoW penalty phase. This may require withholding blocks temporarily if "too far ahead", such that there is a 3vs3 split. Since this could happen, it improves our probability of success compared to the calculations below.
4) Mine at the tip of whichever chain is behind, such that neither side reorgs before finalizing a block on their side of the split. That is, each side must mine 7 blocks w/o being reorg'd. (Must mine 1 before the other mines 4, or 2 before 8, etc.)
--Analysis is for step 4 is complicated and thus omitted below, but this is likely to succeed, and extremely likely to succeed if the network is split close to evenly or if the attacker has substantial hash power.

Analysis:
----------------------------------------------------------
Let x = attacker hash rate; y = main chain hash rate after soft split; z = alt/"attack" chain hash rate after soft split.
-----STEP 1-------------
--Start by assuming the attacker has just mined a block and keeps it secret; then they must win 2 blocks before the honest chain wins 3
--There are 6 possible ways to win: AA, AHA, HAA, AHHA, HHAA, HAHA (A = attacker block; H = honest block.)
Pr[success] = x^2 + 2*x^2*(1-x) + 3*x^2*(1-x)^2
x = 1/20 1.4%
x = 1/10 5.23%
x = 1/4 26.17%
x = 1/3 40.74%
x = 1/2 68.75%
x = 3/5 82.08%
------STEP 2---------------
Ideally, the 4th block for both chains will be of the proper difficulty that would prevent either chain from being reorged by seeing that 4th block, in which case the soft split should persist. This occurs if the following conditions are met:
1) In order to prevent the 4th honest block from reorging our 3 private blocks, we need: privChainWork + 1/2*(privBlock1work + privBlock2work) > mainChainWork
2) In order to prevent the 4th attack block from reorging the 3 public blocks, we need: mainChainWork + 1/2*(pubBlock1work + pubBlock2work) > privChainWork
Note that pubBlock1work == privBlock1work in all cases. Some algebra:
Condition 1 priv1 + priv2 + priv3 + 1/2*priv1 + 1/2*priv2 > pub1 + pub2 + pub3 + pub4
Condition 2 pub1 + pub2 + pub3 + 1/2*pub1 + 1/2*pub2 > priv1 + priv2 + priv3 + priv4
priv1 + priv2 + priv3 > pub1 + pub2 + pub3 + pub4 - (1/2*priv1 + 1/2*priv2)
pub1 + pub2 + pub3 > priv1 + priv2 + priv3 + priv4 - (1/2*pub1 + 1/2*pub2)
pub1 + pub2 + pub3 > pub1 + pub2 + pub3 + pub4 - (1/2*priv1 + 1/2*priv2) + priv4 - (1/2*pub1 + 1/2*pub2)
0 > pub4 + priv4 - (1/2*priv1 + 1/2*priv2) - (1/2*pub1 + 1/2*pub2)
(1/2*priv1 + 1/2*priv2) + (1/2*pub1 + 1/2*pub2) > pub4 + priv4
block1 + 1/2*priv2 + 1/2*pub2 > pub4 + priv4
This is extremely likely if the difficulty is decreasing, which can happen on the private chain by mining blocks with future timestamps, and is likely on the main chain as well, since it will have less hashpower than before the fork point.
------STEP 3------------------------
--What is the probability that both chains mine block 4 before the other mines block 5?
--Assume both chains have 3 blocks already and the attacker has no secret blocks. If the attacker successfully mined block 4 already, our chances would be higher, so this is an underestimate.
--The chance of success depends on how much hash is on each side, which we don't know. Here we analyze two possibilities:
1) y = z (attacker's best case);
2) y = 3z (1/4 of the honest hash is on one side, 3/4 on the other)
--For case 1, assume the miner simply shuts off until one side wins a block, and then immediately mines the other side. They could also pick a side to start with, but we ignore that possibility. For case 2, we assume the attacker mines on the minority chain until a block is mined, and switches if the minority chain wins the first block.
Case 1:
Pr[success] = x + z = x + y
x = 1/20 52.5%
x = 1/10 55%
x = 1/4 62.5%
x = 1/3 66.67%
x = 1/2 75%
x = 3/5 80%
Case 2:
Pr[success] = (x+z)*(x+y) + y*(x+z) = x^2 + 2xy + 2yz + xz
x = 1/20 42.41%
x = 1/10 47.13%
x = 1/4 60.16%
x = 1/3 66.67%%
x = 1/2 78.13%
x = 3/5 84%
-----END STEP 3---------------------


EXAMPLE: Attacker has x fraction of the hash rate, and if he successfully finishes step 1, we assume that the difficulty works out in step 2 about half the time (probably a significant underestimate). Assume that each step is independent (not true, and causes an underestimate of success probability). Assume that the soft split that results splits the hash power 3 to 1, as in case 2 above. What is the probability of getting to the final step of the attack? How many initial blocks can the attacker expect to throw out before succeeding, and how long should this take given their hash rate?
x = 1/20 0.3% 334 blocks thrown out, 6680 blocks total, 46.4 days
x = 1/10 1.23% 82 blocks thrown out, 820 blocks total, 5.7 days
x = 1/4 7.87% 13 blocks thrown out, 52 blocks total, 8.7 hours
x = 1/3 13.58% 8 blocks thrown out, 24 blocks total, 4 hours
x = 1/2 26.86% 4 blocks thrown out, 8 blocks total, 1.3 hours
x = 3/5 34.47% 3 blocks thrown out, 5 blocks total, < 1 hour

DISCUSSION
-------------------------------------------
There are tradeoffs between protecting against chain-split attacks and protecting against deep reorgs, and a chain like that of BCH, with minority SHA-256 hashrate, must tread carefully. However, I think I have demonstrated here that there isn't a tradeoff when you have both parked blocks AND auto-finalization - the security assumption of "everything is fine if majority hashrate is honest" is no longer true, because a 33% attacker can cause a far worse outcome than a deep reorg.
That said, unlike with 51% attacks, this particular attack is one that isn't as likely to be profitable for the attacker financially, so it may not be exploited by random Internet bad guys. Also, it would require some more complicated software and is less likely to succeed without some amount of network intelligence, like knowing which nodes are miners or exchanges to target. However, it CAN still be profitable in a number of ways: shorting BCH, low-conf double spends, and/or the possible selfish mining profits that could accrue from a failure at some step of this strategy.
Timejacking may be useful to smooth over some of the parts of the attack by making sure that a timejacked node will view a block as valid/invalid when the rest of the network doesn't, via timestamp manipulation. This can buy the attacker a little bit of time, and "shape" the network such that he knows which side of the split his targets may be on. Furthermore, if the attacker fails to split the network somewhat evenly, then he can ignore the minority side of the fork and immediately start trying again on the majority side, in an attempt to cause a 3-way split.
Finally, while you may believe that this attack is improbable, the prevailing wisdom of this sub is that a super powerful cabal of bankers will stop at nothing to destroy Bitcoin Cash (operating via their alleged proxy, Blockstream), and since a well-resourced attacker should be able to pull this attack off, I believe y'all should be more concerned than you have been. My recommendation is to remove the parked block functionality from ABC entirely, and accept the risk of medium-length reorgs.
submitted by iwantfreebitcoin to btc [link] [comments]

Groestlcoin Release September 2018

Introduction

As always, the past 3 months since 22nd June have been crazy busy. The bears might still be around, but the show must go on and of course has not slowed the Groestlcoin development team in the slightest. Here’s a quick overview of what has already happened since the last release: - Integrated into the bitbns exchange, with the ability to buy Groestlcoin directly with the Indian Rupee. - Groestlcoin Rebrand Vote – Whilst there was much talk and push for a rebrand vote, the overall result was almost unanimously in favour of keeping our unique and conversation-starting name. With just 83 votes to Rebrand, and 2577 votes to No Rebrand. Thank you for all who voted, the funds raised are being used to fund ongoing hosting and development costs. - Integrated into the Cryptobridge exchange. Cryptobridge is a popular decentralised exchange where you always hold the private keys to your funds, only YOU have access to them. - Groestlcoin has been added to SimpleSwap – Groestlcoin can now be swapped with over 100 other cryptocurrencies, without signing up! - Groestlcoin has been added to UnoDax, one of the leading cryptocurrency exchanges in India, with TUSD, BTC and INR trading pairs. - Groestlcoin has been added to SwapLab.cc, where you can buy Groestlcoin using Bitcoin and over 50 other altcoins. Purchasing with VISA/Mastercard is coming VERY SOON. Discussed later: - Groestlcoin has been listed on #3 largest exchange in the world on volume, Huobi Global! More on this to come further on in the announcements. - Groestlcoin has been added to the Guarda Multi-Currency Wallet. - Groestlcoin has been added to Melis Multi-Device, Multi-Account, Multi-Platform, Multi-Signature advanced wallet! Already this list is far more than most other cryptocurrencies have achieved in the past 3 months. But this is just the tip of the iceberg of what has been developed.

What's been Happening?

GRSPay Released

We are so excited for this, that it has it's own separate reddit thread. Head over there now at https://www.reddit.com/groestlcoin/comments/9ikr5m/groestlcoin_releases_grspay/? to see more on this!
https://www.melis.io/assets/logo-navbar-4b6f0d372f15b2446d3fa4c68f346e4fb08ee113941186cee58fd6135f3f8b7d.svg

Melis Wallet

The the most advanced wallet for Bitcoin, Bitcoin Cash, Litecoin and now Groestlcoin.
With Melis you have the complete control of your bitcoins and private keys, you can define spending limits policies and make use of two or more factors authentication. Melis is open source, published on GitHub.

How Melis Works?

You can create as many accounts as you want. An account is a part of your wallet that can be customised to your requirements. You can choose how many co-signers are required to spend funds. The accounts are completely independent and act like separate wallets from each other but can be accessed via the same details. A core feature of Melis is the ability to set a ‘primary’ device. With this you can set an account as ‘Secure’ so it is only viewable (and accessible at all) from the Primary device. You can have a savings account hidden from the outside world whilst also having your ‘spending’ funds available on the go. With Melis you can create a multi-signature account between N people, where up to N signatures are required to sign a transaction, choosing if any of those should be mandatory.
Core Features:
https://guarda.co/assets/images/1PGo4ID.svg?1537791124643

Guarda Wallet

Safer than ever! Desktop Light Wallet - Anonymous and fast!
With Guarda Multi-currency Desktop Light Wallet you don’t need to register. Guarda has no access to your private keys or funds. You can receive, send, store, buy and exchange cryptocurrencies in complete anonymity and safety. All these features are available on Linux, Windows or MacOS. Choose the one that suits you!
More info about Guarda wallet on www.guarda.co
https://holytransaction.com/images/logo.png

Integrated into HolyTransaction

What is HolyTransaction?

HolyTransaction gives users access to the crypto world with a universal cryptocurrency wallet and instant exchange.

Features

For more information, visit Holy Transaction here.
https://www.groestlcoin.org/wp-content/uploads/2018/09/next-grs-groestlcoin.jpg

Integrated into NEXT Wallet

What is NEXT?

NEXT is a modern, next-generation stylish open-source Desktop wallet.

Features

For more information, visit NextWallet here.
https://blockchainfinancial.com/mediaserve2018/09/admin-06143647-bcf_logo_vec_256x256.png

Integrated into Blockchain Financial

What is Blockchain Financial?

Blockchain Financial is a set of web based services for individuals and companies that want to make things happen with the Cryptocurrencies Ecosystem. - For those that don't know anything about cryptocurrencies, we offer tools that will let them receive, send and operate with an assortment of coins. - For those that are already riding the wave, we offer tools that will let them do all those things that they weren't able to do.

Blockchain Financials mission

We're not here to reinvent the wheel. We're here to make it run smoother for you, and we provide some of the most useful services you'll find on the internet, made in a way that is easy to understand and use on a daily basis. In short, we're a bunch of people that claim to be Crypto Evangelists. We strongly believe in cryptocurrencies, and our main promise is to push them up so more people get involved and take all the advantages they offer.

More information from Blockchain Financial

Back in 2014, the world was taken by storm when Facebook approved the first cryptocurrencies tipping apps. The first was for Dogecoin, and the second was for multiple coins.
The project was hosted on whitepuma.net, and persisted for almost two years, built up a massive user community and gave a home to Bitcoin, Litecoin, Dogecoin and dozens of other bitcoin-based altcoins.
After very active months, the tipping hype started to fade away. Then, the developers decided to jump into the next stage: bringing not only tipping, but also mining and a widget that could be embedded on websites to allow everyone to accept payments. Sadly, the work was never completed because the project started to require an unsustainable amount of resources. Then, in a painful decision, a shutdown was announced by December 2015.
A couple of months after whitepuma.net was closed, the source code was released by its creator as Open Source on GitHub. But it wasn't maintained.
Now, some of the original members of the dev and admin teams gathered up with a handful of the WhitePuma's elite users, and decided to make something good with the best pieces of the old source code. That, with fresh new ideas and the power of the BardCanvas engine, synthesized the core of Blockchain Financial.
More info about Blockchain Financial wallet on .
For more information, visit [Blockchain Financial](www.blockchainfinancial.com)
https://www.huobi.com/image/logo.aeb4723.svg

Groestlcoin Listed on Huobi

Who are Huobi?

Huobi was founded in China and is now based in Singapore, with offices in Hong Kong, South Korea, Japan and the North America, currently sitting #3 in volume on Coinmarketcap. Huobi is a great leap forward for our growing presence in Asia and we are very excited to be listed here!
You can find the official Huobi announcement here.

Groestlcoin Core v2.16.3 - Please Update ASAP

A new major Groestlcoin Core version 2.16.3 is now available for download which includes both a Denial of Service component and a critical inflation vulnerability, so it is recommended to upgrade to it if you are running a full Groestlcoin node or a local Groestlcoin Core wallet.
v2.16.3 is now the official release version of Groestlcoin Core. This is a new major version release with a very important security updates. It is recommended to upgrade to this version as soon as possible. Please stop running versions of Groestlcoin Core affected by CVE-2018-17144 ASAP: These are 2.13.3 and 2.16.0.
As a result in this, all exchanges and services have been asked to upgrade to this version, so please be patient if wallets go in to maintenance mode on these services.

What's new in version v2.16.3?

This is a major release of Groestlcoin Core fixing a Denial of Service component and a critical inflation vulnerability (https://nvd.nist.gov/vuln/detail/CVE-2018-17144) exploitable by miners that has been discovered in Groestlcoin Core version 2.13.3 and 2.16.0. It is recommended to upgrade to 2.16.3 as soon as possible. If you only occasionally run Groestlcoin Core, then it's not necessary to run out and upgrade it right this second. However, you should upgrade it before you next run it. If you know anyone who is running an older version, tell them to upgrade it ASAP. Stored funds are not at risk, and never were at risk. At this time we believe over half of the Groestlcoin hashrate has upgraded to patched nodes. We are unaware of any attempts to exploit this vulnerability. However, it still remains critical that affected users upgrade and apply the latest patches to ensure no possibility of large reorganizations, mining of invalid blocks, or acceptance of invalid transactions occurs.

The Technicals

In Groestlcoin Core 2.13.3, an optimization was added (Bitcoin Core PR #9049) which avoided a costly check during initial pre-relay block validation that multiple inputs within a single transaction did not spend the same input twice which was added in 2012 (Bitcoin Core PR #443). While the UTXO-updating logic has sufficient knowledge to check that such a condition is not violated in 2.13.3 it only did so in a sanity check assertion and not with full error handling (it did, however, fully handle this case twice in prior to 2.1.0.6). Thus, in Groestlcoin Core 2.13.3, any attempts to double-spend a transaction output within a single transaction inside of a block will result in an assertion failure and a crash, as was originally reported. In Groestlcoin Core 2.16.0, as a part of a larger redesign to simplify unspent transaction output tracking and correct a resource exhaustion attack the assertion was changed subtly. Instead of asserting that the output being marked spent was previously unspent, it only asserts that it exists. Thus, in Groestlcoin Core 2.16.0, any attempts to double-spend a transaction output within a single transaction inside of a block where the output being spent was created in the same block, the same assertion failure will occur. However, if the output being double-spent was created in a previous block, an entry will still remain in the CCoin map with the DIRTY flag set and having been marked as spent, resulting in no such assertion. This could allow a miner to inflate the supply of Groestlcoin as they would be then able to claim the value being spent twice.
Groestlcoin would like to publicly thank Reddit user u/Awemany for finding CVE-2018-17144 and reporting it (https://lists.linuxfoundation.org/pipermail/bitcoin-core-dev/2018-Septembe000064.html). You deserve gratitude and appreciation from cryptoworld, and you have ours. If you want to support him for his work, please consider donating to him on his bitcoin cash address: bitcoincash:qr5yuq3q40u7mxwqz6xvamkfj8tg45wyus7fhqzug5
http://i.imgur.com/3YhyNZK.png

Groestlcoin Electrum-GRS 3.2.2 - Ledger & Trezor Edition

What is Electrum-GRS?
Electrum-GRS is a lightweight "thin client" groestlcoin wallet Windows, MacOS and Linux based on a client-server protocol. Its main advantages over the original Groestlcoin client include support for multi-signature wallets and not requiring the download of the entire block chain.

Changes:

http://i.imgur.com/3YhyNZK.png

Electrum-GRS Mobile Android

What is Electrum-GRS Mobile?

Electrum-grs is a lightweight "thin client" groestlcoin wallet Android based on a client-server protocol. Its main advantages over the original Groestlcoin client include support for multi-signature wallets and not requiring the download of the entire block chain.

Changes

Groestlcoin EasyVanity Released

Groestlcoin EasyVanity is a Windows app is built from the ground-up in C# and makes it easier than ever before to create your very own bespoke Groestlcoin address(es), even whilst not connected to the internet! You can even generate multiple keys with the same prefix and leave it on overnight whilst your CPU or GPU collects and stores these addresses locally.
If you're tired of the random, cryptic addresses generated by regular groestlcoin clients, then Groestlcoin EasyVanity is the right choice for you to create a more personalized address.

Features

• Ability to continue finding keys after first one is found • Includes warning on startup if connected to the internet • Ability to output keys to a text file (And shows button to open that directory) • Ability to make your match case sensitive (Where possible) • Show and hide the private key with a simple toggle switch, and copy the private key straight to your clipboard • Show full output of commands • Includes statistics whilst the application is running • Ability to choose between Processor (CPU) and Graphics Card (GPU) • Automatically detects 32 or 64 bit systems • Features both a Light and Dark Material Design inspired Themes • EasyVanity's search is probabilistic, and the amount of time required to find a given pattern depends on how complex the pattern is, the speed of your computer, and whether you get lucky. • EasyVanity includes components to perform address searching on your CPU (vanitygen) and your OpenCL-compatible GPU (oclvanitygen). Both can be built from source, and both are included in the Windows binary package. • Prefixes are exact strings that must appear at the beginning of the address. When searching for prefixes, Easyvanity will ensure that the prefix is possible, and will provide a difficulty estimate. • The percentage displayed just shows how probable it is that a match would be found in the session so far. If it finds your address with 5% on the display, you are extremely lucky. If it finds your address with 92% on the display, you are unlucky. If you stop EasyVanity with 90% on the display, restart it, and it finds your address with 2% on the display, your first session was unlucky, but your second session was lucky. • EasyVanity uses the OpenSSL random number generator. This is the same RNG used by groestlcoin and a good number of HTTPS servers. It is regarded as well-scrutinized. Guessing the private key of an address found by EasyVanity will be no easier than guessing a private key created by groestlcoin itself. • To speed up address generation, EasyVanity uses the RNG to choose a private key, and literally increments the private key in a loop searching for a match. As long as the starting point is not disclosed, if a match is found, the private key will not be any easier to guess than if every private key tested were taken from the RNG. EasyVanity will also reload the private key from the RNG after 10,000,000 unsuccessful searches (100M for oclvanitygen), or when a match is found and multiple patterns are being searched for. • Free software - MIT. Anyone can audit the code. • Written in C# - The code is short, and easy to review.

Groestlcoin Sentinel (Android & Blackberry) – Mainnet + Testnet

What is Sentinel?

Groestlcoin Sentinel is the easiest and fastest way to track/receive/watch payments in your offline Groestlcoin Wallets. Groestlcoin Sentinel is compatible with any standard Groestlcoin address, BIP44 XPUB (Extended Public Key) BIP49 YPUB and BIP84 ZPUB
Groestlcoin Sentinel is a great solution for anyone who wants the convenience and utility of a hot wallet for receiving payments directly into their cold storage (or hardware wallets). Sentinel accepts XPUB's, YPUB'S, ZPUB's and individual Groestlcoin address. Once added you will be able to view balances, view transactions, and (in the case of XPUB's, YPUB's and ZPUB's) deterministically generate addresses for that particular wallet.

What's New?

The P2SH paperwallet supports creating P2SH paperwallets in bulk, keypair generation with QR codes and sweeping tool. Groestlcoin believes strongly in privacy, the live version does not collect and store IP or transaction data.
Changes
Features
The BECH32 paperwallet supports creating BECH32 paperwallets in bulk, keypair generation with QR codes and sweeping tool. Groestlcoin believes strongly in privacy, the live version does not collect and store IP or transaction data.
Features
![WebWallet](https://i.imgur.com/Z2oj7bj.png)

Groestlcoin Web Wallet Update 1.4

What is Groestlcoin Web Wallet?
Groestlcoin Webwallet is an open source, multisignature, HD Wallet and more! Webwallet is a a open source browser based Groestlcoin webwallet.
Webwallet is a playground for Groestlcoin in javascript to experiment with. It supports multisig, OP_HODL, RBF and many more. Groestlcoin believes strongly in privacy, the live version does not collect and store IP or transaction data.
Changes:
submitted by Yokomoko_Saleen to groestlcoin [link] [comments]

Why NYA is an attack on Bitcoin and why it will fail (long)

I wrote a rather lengthy response to a reddit post that I think is worth sharing, especially for newcomers to dispell some false narratives about S2X and Barry Silberts' New-York Agreement aka hostile takeover attempt of Bitcoin that is doomed to fail.
big block hard-liners wanted block size only, no SegWit.
Which doesn't make any logical sense. A lot of fud was actively being spread about how segwit was unsafe (such as the ANYONECANSPEND fud) but segwit is ofcourse working as intended thanks to the world class engineering of the Bitcoin Core developers. This led to the suspicion that BitMain was behind the opposition of segwit. BitMain miners use "covert AsicBoost" which is a technique that allows their rigs to use less electricity than competing mining equipment. However, segwit introduced changes to Bitcoin that made using covert AsicBoost impossible, which would explain their fierce opposition to segwit. We're talking big money here - the AsicBoost advantage is worth US$ 100 million according to estimates of experts.
After segwit was finalized, the Bitcoin software was programmed to activate segwit but not before 95% of the hashpower signalled to be ready. After all, miners are tasked with creating valid blocks and should be given the opportunity to update their software for protocol changes such as segwit. As a courtesy to the miners, the Bitcoin software basically said: "ok, segwit is here, but I'll politely hold off its activation until 95% of you say that you're ready to deal with this protocol change".
Sadly, mining is heavily centralized, and segwit was never getting activated due to the opposition of a few or perhaps even a single person: Jihan Wu of BitMain. As an aside, the centralization of hash power is also a direct result of AsicBoost. How this works: since AsicBoosted rigs are able to mine more efficiently than their competitors, these rigs drive up the difficulty and with that the average amount of hashes required to find a block. This in turn causes less efficient rigs to mine at a loss because they need to expend more energy to find a block. As a result, BitMain competitors got pushed out and BitMain became the dominant self-mining ASIC manufacturer.
After segwit was finalized, it required 95% of the hashpower to activate but it never gained more than around 30%. So 70% of hash power abused the courtesy of the Bitcoin software to wait until they were ready for activation and refused to give the go ahead. This went on for months and worst case it would have taken until August 2018 before segwit would activate.
let's do a compromise- we do SegWit AND we hard fork
In March 2017 a pseudonymous user called Shaolin Fry created BIP148 which is a softfork that invalidates any block that wouldn't signal segwit readiness starting August 1st 2017. This also became known as the UASF (User-Activated Soft Fork, as opposed to the original miner-activated soft fork that didn't work as intended). This patch saw significant adoption and miners would soon be forced to signal segwit or else see their blocks being invalidated by the network, which would cause them significant financial losses.
In May 2017 so after BIP148, the backroom New-York Agreement (NYA) was created by the Digital Currency Group of Barry Silbert together with businesses in the Bitcoin space such as BitPay and almost all miners. The NYA was the beginning of an outright misinformation campaign.
The NYA was trumpeted to be a "compromise". Miners would finally agree to activate segwit. In return, Bitcoin would hardfork and double its capacity on top of the doubling already achieved by segwit. In reality, BIP148 was already going to force miners to signal the activation of segwit. Also, developers and most users were notably absent in this NYA. So, given that segwit was already unstoppable because of BIP148, the parties around the table had to "compromise" to do something that they all wanted: hardfork Bitcoin to increase its capacity.
Or, is it all in fact really about increasing capacity? After all, segwit already achieved this. Bcash was created which doubled block size as well but without segwit. And then there is good old Litecoin having four times the transaction capacity of Bitcoin and segwit. Plenty of working alternatives that obsolete the need for yet another altcoin. So, perhaps transaction capacity is used as an excuse to reach a different goal. Let's explore.
Apparently after not-so-careful study of the Bitcoin whitepaper, the NYA participants came up with an absurd redefinition of what is "Bitcoin". According to this bizarre definition, they started to claim that Bitcoin is being defined as:
  1. Any blockchain that has the most cumulative hashpower behind it (measured from the Genesis block at the inception of Bitcoin):
  2. Using the SHA256 hashing algorithm;
  3. Having the current difficulty adjustment algorithm (resetting difficulty every 2016 blocks).
Ad 1. Note that it starts with "any blockchain". This also includes blockchains that contain invalid blocks, in other words, blocks that Bitcoin nodes would reject.
This is ofcourse bizarre but it is exactly what the NYA participants claim. It effectively puts all power in the hand of miners. Instead of nodes validating blocks, according to this novel and absurd interpretation of Bitcoin it will be miners that call the shots. Whatever block a miner produces will be valid as long as they mine on top of their own block, because that chain will then have the most cumulative hash power. Nodes become mere distributors of blocks and lose all their authority as they can no longer decide over the validity of a block. MinerCoin is born.
The Bitcoin whitepaper actually mentions this scenario where a majority of the hashpower takes over the network and starts producing invalid blocks and refers to it as being an attack. It is worth quoting this section 8, second paragraph in its entirety:
"As such, the verification is reliable as long as honest nodes control the network, but is more vulnerable if the network is overpowered by an attacker. While network nodes can verify transactions for themselves, the simplified method can be fooled by an attacker's fabricated transactions for as long as the attacker can continue to overpower the network. One strategy to protect against this would be to accept alerts from network nodes when they detect an invalid block, prompting the user's software to download the full block and alerted transactions to confirm the inconsistency. Businesses that receive frequent payments will probably still want to run their own nodes for more independent security and quicker verification." (emphasises mine).
Any doubt left whether "most hashpower wins" is an attack should be removed by a telling remark in the release notes of 0.3.19:
"Safe mode can still be triggered by seeing a longer (greater total PoW) invalid block chain."
As mentioned, miners representing 95% of all hash power participate in the NYA. They are currently expressing their support for the NYA by putting "NYA" inside blocks. The NYA participants intend to remove their hash power from Bitcoin completely and point it towards their altcoin. To double down on their claim that Bitcoin is defined by hashpower, they show some serious audacity by referring to their altcoin as... "Bitcoin". Anyone not part of the NYA refers to their coin as segwit2x, S2X or sometimes 2x.
The NYA participants proceed to proclaim victory. They reason that with all hash power on their blockchain and hardly any left for Bitcoin, "legacy Bitcoin" will be stuck as blocks will be created so slowly that Bitcoin becomes unusable, forcing everyone to switch to the "real" Bitcoin (sic). In other words, it was part of the plan was to remove hash power from Bitcoin to disrupt and force users into their altcoin.
Ofcourse, Bitcoin Core would not just sit idle and let such an attack happen. There are several ways to defend against this attack. As a last resort, an emergency difficulty reset combined with a change in the PoW algorithm can be deployed to get Bitcoin going again.
This is not likely to be necessary however as miners simply can't afford to mine a coin that has a small fraction of the value of Bitcoin. They have large bills to pay which is impossible by mining a coin that has half or even less the value of Bitcoin. In other words, miners would bankrupt themselves unless their altcoin attains the same value as Bitcoin. Given the lack of user, community and developer support it is save to say that this is not going to happen. Their coin will have only a small fraction of the value of Bitcoin and miners have no choice but to continue mine Bitcoin in order to receive the income necessary to pay for their huge operational expenses.
A moment was set for the hardfork: block 494,784 a big block will be produced such that it is invalid for the current Bitcoin network and will discard it.
Ofcourse, some nodes must accept the new, bigger S2X blocks. Therefore, Jeff Garzik (co-founder of a company called Bloq) started out to create btc1 which is a fork of the Bitcoin node software and which is adapted such that it accepts blocks up to twice in size, so that the segwit2x altcoin can exist. Note the 1 in btc1 which refers to their version numbering. Bitcoin Core releases are still 0.x but btc1 is numbered 1.x. This is to send the message that they have released the real Bitcoin that is now no longer a beta 0.x release but a production ready 1.x. This nonwithstanding the fact that btc1 is a copy of Bitcoin 0.14 with some minor changes and without any significant development causing it to quickly fall behind Bitcoin.
The NYA participants go on to claim that when hash power is on the btc1 blockchain, and Bitcoin is dead as a result because no or hardly any new blocks are being created, then the Bitcoin Core developers have no choice but to start contributing to their btc1 github controlled by Jeff Garzik.
In the NYA end state, Bitcoin is a coin of which miners set the consensus rules, and the Core developers sheepishly contribute to software in a repository controlled by Jeff Garzik or whoever pays him.
Needless to say, this is never ever going to happen.
The small block hard-liners are now against 2x and want SegWit only.
There is no such thing as small block hardliners. As is probably clear by now, NYA is not about block size. It is about control over Bitcoin. As a matter of fact, Bitcoin Core has never closed the door on a block size increase. In the scaling roadmap published in December 2015, Bitcoin Core notes:
"Finally--at some point the capacity increases from the above may not be enough. Delivery on relay improvements, segwit fraud proofs, dynamic block size controls, and other advances in technology will reduce the risk and therefore controversy around moderate block size increase proposals (such as 2/4/8 rescaled to respect segwit's increase). Bitcoin will be able to move forward with these increases when improvements and understanding render their risks widely acceptable relative to the risks of not deploying them. In Bitcoin Core we should keep patches ready to implement them as the need and the will arises, to keep the basic software engineering from being the limiting factor."
Bitcoin Core literally says here very clearly that further increases of block size are on the table as an option in the future.
For my personal opinion-
I hope that your personal opinion has changed after taking notes of the above.
submitted by trilli0nn to Bitcoin [link] [comments]

UPDATE: We studied Blue Apron to figure out how to ship Maryland crabs to your home

We have come a long way since our first post (6 months ago), here!
I plan to continue updating our progress every 6 months, highlighting our mistakes and our hits in hopes your can utilize some ideas to help your ecommerce and the difficult business that is fresh (24 hours) perishable shipping.
Who we are: https://www.cameronsseafood.com/in 1985 my Dad and Uncle started the Maryland Seafood business and today it does $20 million in gross revenue each year. We sell raw and cooked seafood, and prepared dishes at 14 locations — 11 storefronts and three trucks — We have over 1,000,000 customers in the Baltimore-Washington-Philadelphia market. On June 24th 2017 my cousin and I started the nationwide home shipping business as a separate entity. The operation is run by me, my wife, dad, uncle, brother, cousin and 60 employees. I have no ownership in the stores, food trucks, and franchises. My uncle owns and handles all that.
My Background: the business was named after me in 1985 as I am the oldest son of 6 children. My main business is apartment brokerage and investing. I have been a MD, DC, and VA broker for 17 years www.idealrealty.com. I sell 100+ unit complexes to institutions and high net-worth individuals.
Coolest Online Customers: Gilbert Arenas and Mia Khalifa
What seafood do we sell online: Virtually everything but, 85% of sales are Maryland crabs, Maryland crab cakes, Maryland crab soups, and Free shipping samplers.
What we do: we ship freshly cooked Maryland Blue Crabs, Crab cakes and seafood to your door in 24 hours after being caught in the Chesapeake Bay, Maryland. We send you seafood that is 3 days fresher than the grocery store. Btw, we accept bitcoin!
Where do we get our Seafood? Chesapeake Bay, Maryland for Maryland products, using our own crabbers and contracted crabbers over the past 32 years. Although our COGS is 30%, shipping with 1-2 day delivery is very expensive, with the packaging materials outweighing the FedEx fees. We ship it fresh with Snow/King crab legs, soft shells (in off-season) and lobster tails being the items we ship frozen. Some items we receive frozen like Bee Gee shrimp from Louisiana.
We are True Blue Certified, meaning In order to be True Blue certified, participating food service establishments commit that at least 75% of their annual crab usage will be from Maryland harvested or processed crabs.
Startup Leverage: We do have some amazing advantages and you should tab into yours: 1) We don’t pay rent because we operate out of my uncles seafood headquarters. 2) We don’t need employees to handle extra orders (my partners handles up to 50 orders a day by himself) because we can use our existing employees. 4) We don’t have “employees” we contract existing employees meaning you don’t have to pay 15% tax 3) We don’t have food spoilage because we buy only what we need from our the stores each morning.
Online Profit Margins: We aim for 35% gross margins with our cost of goods sold at 30%. However, packaging and shipping costs wipe out most of it while paid-advertisement has wiped out the rest leaving us with 10% gross for the first 6 months. 1) We eliminated AdWords since our ROI/customer acquisition costs were too high. 2) We reduced all packaging costs through trial and error. We eliminated anything not necessary then negotiated each material with three vendors. You need to create a bidding war. 3) We negotiated shipping rates by switching vendors 3x. We formed a strategic partnership to tab into their FedEx account. With a growing customer base we are on track to hit 30% gross next year but it’s possible to hit 40% and 10% net.
Free Shipping Model: We offer free shipping to 29 states (1-2 day zones through FedEx ground network) when a customer spends over $200. Since our average order is $160 we think that’s a solid minimum order. We offer flat-rate air shipping everywhere else. National shipping is $94.99 or $79.99 when they spend $200+. We offer many free shipping sampler combos to local and regional customers. It’s too expensive to ship nationally without ridiculous pricing. That’s ok, if we can capitalize on the 29 ground states we will hit our $20,000,000 number. We don’t make any money on shipping, and I wish we could. Shipping page.
Chargeback Fraud: people are creative and fraud has cost us thousands We cannot require signatures on shipments without incurring a $4.50 fee and what if the person isn’t home? FedEx will return the box to their hub subjecting it to transit issues and spoilage. A lot of our customers order our food as gifts so the billing and shipping don’t match. We learned you can get expensive software that charges a per transaction fee. It’s only worth if at higher volume but you can do your own fraud detection. For example, look up the shipping address in google maps. Google the person and look for articles about them to show they live in the state. Modify your payment processor’s security features so you can monitor the results. We noted most fraudsters order our frozen items (to store or resell them) so we carefully review each frozen order with wide eyes.
Losses: We have made many errors totaling $15,000. Shipping wrong items, missing items, item arrives late or spoiled, gel packs melt, things happen. The important thing is to address the root cause, which helped us lower our losses rate from 15% down to 5% with a 3% goal in mind for 2018.
Shipping – pin FedEx vs UPS and save money. Make sure the “rates” include a residential fee and fuel fees. Also know like new credit cards they will give you introductory rates that eventually run out and use your monthly sales volume to adjust up/down. Negotiate longer into rate periods if you can! UPS offers insurance on the entire sale and will grant 25% off next day air on any bad deliveries and charge $1.80 per $100 but there is a catch. Your customers need to provide you photo proofs, and UPS has to be at fault to receive a claim (late delivery which occurs less than 1%) or a forgetting to deliver. However, UPS has abysmal Saturday ground delivery networks as it’s new as of August 2017 when FedEx has the entire network open. UPS has a smaller ground delivery range that FedEx too. No brainer for us, we chose FedEx. We don’t take insurance because it’s a loss. This will depend on your line of business.
Packaging Perishables – we reverse engineered Blue Apron and competitors to figure out how to ship fresh (and live) seafood. It also teaches you where to find suppliers (use manufacturers not resellers as they have a markup). Call them and form relationships.
Gel Packs: It takes 5 weeks to properly freeze a gel pack! I thought our business was doomed when I learned this because how can I store that many gel packs and replenish them within my walk-in freezer? Solution: we pay for pre-frozen ones and have pallets stored at -10. We learned this from ordering from Blue Apron and calling the gel pack manufacturer.
Boxes: to ship perishable seafood you probably need an insulated cooler and corrugated box kit. Since we started, we reduced costs by 30% by searching for a manufacturer (not a distributor) that can cut costs and store surplus for us. Costs include freight so find someone local within 1-2 hours of your HQ.
Customer Service: We sell seafood but we are in the customer service business. We are open 7 days per week and either I or my brother will answer your phone calls (888-404-7454 x1). Our competitors are only open 5-days per week. We offer cash refunds and reshipments on any customer complaint. Our competitors may give you a credit on your next order…The customer is always right and we ensure 100% satisfaction guaranteed. This has converted customers to repeat customers. We treat each customer as we want to be treated. Give a little, get a lot.
Website: I know you think I am biased because my wife created our site from scratch but she did an amazing job for her first ecommerce site! We modify content daily and advertise to our email list once per week with discount codes. This would have cost me $10,000 to $30,000 with all the changes we have made. It’s constantly evolving and the project never ends. Find a good partner that will grow with you. No 3rd party will put in the passion a strategic partner could offer. Try offering a lower hourly rate but give them a piece of the action for the difference.
Advertising: The best advertisement for us has been word-of-mouth. We carry 5-star reviews on Facebook but getting satisfied customers to review is hard (after a sale they receive an email asking them to rate their experience). We thought about offering a coupon but it feels like a bribe. We do offer a coupon once someone abandons their cart to remarket. We send out weekly coupons via mailing list and we offer weekly storewide specials (the real savings happen when you sign up). Social media is free, get good at it. Learn which outlets suit your business. For us, Facebook and Instagram work whereas Twitter has no traction. I learned ads on social media don’t convert. Nobody wants to be spammed ads. They want to discuss a topic and engage on pictures, videos, and education about your field. They will find a way to buy from you. Instead of offering a coupon teach them a recipe, explain why a Maryland Crab is the world’s best crab (in the Chesapeake Bay, due to the specific climate, the Blue Crabs lie dormant for 6 months and form a layer of fat on their meat which gives them a their sweat buttery flavor!). You see, that’s interesting! When you post ask yourself how will this engage an audience? You want to advertise? Then try doing giveaways using www.gleam.io, which has amazing social networking tools to spread the word.
Facebook is another animal where most of our success has been through remarketing. Currently, we are brainstorming both organic and paid Facebook ideas…I’m open to any suggestions. Getting customers to your homepage is the hardest part. Once they get there, your site has to convert them. When we started, we used Adwords to bring attention to our product pages but we had no other supportive information to convert them. We recrafted each page to stand on its own (assuming they never leave that page) and doubled our conversion rates!
We outsource our SEO/AdWords to a company that we learned about through our first Reddit Post. SEO can take at least 6+ months to build up your keywords on the rankings list. You need to be on the 1st page or you won’t convert traffic. We started with most organic keyword rankings on the 64th page and are have almost all of our keywords now on the 3rd page. By February most of our keywords should be on the 1st page! Many things went into this including getting quality backlinks, blogging 6 times per month with SEO rich content, carefully titling each page, section, and product; and Keyword/URL optimization.
Adwords: We foolishly spent $42,000 on AdWords and ended our campaign with $37 cost per conversion and 186.29% ROI, which doesn’t allow us to make profit during the off-season (crabs are seasonal from April to November) so we will try again in Q2, 2018.
Influencers: overall this hasn’t been profitable. We have social media influencers with 100k+ dedicated seafood/food followers whereby we grant them a vanity link and discount but it hasn’t worked. We belong to several influencer networks were they receive 8% for posting banner adds, this has only brought in $10,000…
Mia Khalifa: We reached out to Mia as she has the strongest influences (4m+ followers) for a Maryland native that loves our seafood. We sent her food and she spent a week hyping the brand including social media posts, PMs and featured a Twitch episode about Cameron’s. Definitely drove tremendous traffic although we can only ship to the USA due the transit time lag of customs. We look forward to working more with her.
Gilbert Arenas: I’m a huge Gilbert and Wizards fan! He replied to Mia’s post and a PM worked to get his interest. He is a real character and orders a lot of our seafood each month. He love the high-protein variety that (Maryland) seafood provides. Chicken and vegetables does get boring.
Washington Post: We were featured in the Washington Post on Dec 1st, see here. They did a good job summarizing our business so far. We have also been featured in Forbes, New York Times, Huffington Post and more. How? I googled the food reviewer from each of the above and figured out their contact info. Sent them a 2-line email asking them to review our food and boom!
Videos We started sharing videos of the entire process so you can see the experience before you risk order fresh seafood online. We plan to continue posting new videos in 2018 and I’d love feedback on what you would like to see?
What we do
First Customer Unboxing
Another unboxing
Resteam Maryland Crabs (gif recipe style)
Packaging demo
2018 Goals
Please provide us any feedback or ideas. We want to get better and need your help.
Discount code "holiday" will save you 10% on all order and we accept Bitcoin!
submitted by comikins to Entrepreneur [link] [comments]

Are There Any Bricks-and-Mortar Merchants Still Accepting Bitcoin Core (BTC)?

Blockstream/Core has chosen a path of settlement/SoV for Bitcoin Core (BTC), leaving Bitcoin Cash (BCH) to pursue the original intent of the Bitcoin whitepaper namely - electronic commerce. As a bricks-and-mortar merchant, applying a settlement/SoV system for what is clearly an electronic commerce application has obvious limitations (outlined specifically below).
Given that Bitcoin Core (BTC) has 10x transaction load of Bitcoin Cash (BCH), it is tempting to assume BTC has 10x the number of bricks-and-mortar merchants also.
So, are there any bricks-and-mortar merchants still accepting Bitcoin Core (BTC) and if so, how have they adjusted to the limitations of using a settlement/SoV system for electronic commerce?
  1. Blockstream/core added Replace-by-Fee (RBF) whereby merchants must detect a customer setting the RBF flag or risk having the funds stolen with an effortless RBF double-spend when the customer leaves the store. Merchants detecting RBF should consider withholding goods until the TX is confirmed.
  2. Blockstream/core instituted artificial congestion with their 1MB blocksize limit. Thus, for the merchant to consider accepting 0-conf, a merchant must examine the customer's TXs fee with respect to the Mempool fee distribution and Mempool size to ensure the customer's TX joins the top 2000 Mempool TXs (those likely to be included in the next block) for an acceptable 0-conf risk (A customer must also check the Mempool fee distribution and size in order to meet the fee and RBF flag conditions that the merchant sets or suffer the variable wait time for their TX to confirm which could very well skip several blocks).
  3. If a merchant can see the customer's TX in the top 2,000 Mempool transactions, at what rate are new TXs joining the Mempool and how likely will the customer's TX be bumped from the set of TX's included in the next block (A situation further complicated by block time variance)?
  4. Merchants must contend with nonlinear fee rises with each uptick in speculation or trade.
submitted by where-is-satoshi to btc [link] [comments]

"Why RaiBlocks is not secure"

I found the following text at Bitcointalk. I'm a Raiblocks holder and I find it fascinating, but I don't know enough about the technicalities and I'm worried about the author being right. I'd apreciate if someone could explain if he's wrong (don't be a troll downvoting, I have invested money in this coin and I'm considering buying more as so far it seems fantastic to me).
https://bitcointalk.org/index.php?topic=1381323.msg27277903#msg27277903
  1. Decentralized payments Decentralized payment networks are, in opposite of centralized payment network like banks, a way to secure your money without having the risk that a central authority could steal your money or manipulate the money in the market. Decentralized payment networks use asymmetric cryptography to ensure that you are the only one who can spend your money. When you create a cryptocurrency wallet you are given a public key and a private key. The public key allows other people to send you money, while the private key allows you to spend them.
But how other users know how many money do you have? To accomplish this, every user of a decentralized payment network must download the entire transaction database which is replicated on the entire network. When you send a payment over the network, it is received by all the users connected on the network allowing them to know your updated wallet balance and allowing them to discard that payment if you don’t own enough funds.
  1. Double Spending The main problem that afflicts decentralized payment networks is double spending: the ability of an user to spend his money multiple times. In the real world, when you pay someone you give him the real cash. In a centralized payment network, like VISA, the central database is updated every time you make a payment, and they will not allow you to spend more money than your balance. In a decentralized payment network what happens if you send the same amount of money on two users of the network in the same time? Since their database takes time to update for a small amount of time they both will receive the payment and accept it. In a later moment, when the network tells them that you double spent your money, they will cancel the payment, this is possible because every payment is broadcasted to the entire network, not only the receiver. Without any other security layer, if a malicious user double spends his money and succeeds to block a payment receiver to know that he sent the same money to someone else (or even better, to another wallet of his own), the payment receiver will accept the payment and ship the good. This is so bad, since even a network connection problem could temporarily lead a payment receiver to undetect double spendings.
  2. The Bitcoin Solution To solve this problem, Bitcoin relays on the fact that after you receive a payment you need to wait a confirmation block, the confirmation block tells you that the payment you have received has been accepted by the entire network and you are allowed to spend it. To create a confirmation block, the miners create a list of all the pending unconfirmed transactions and solve a very difficult mathematical puzzle. The miner who solves the puzzle first, sends the block he found with all the list of confirmed transaction and the solved puzzle to the network, the users of the network will check if the puzzle solution is valid and then reward him with some free coins plus the sum of all the payment fees of each transaction in the block. The miners must create a valid list of payments to be accepted by the network, so double spend attempts are just discarded.
In Bitcoin an attacker, to make a succesful double spending, should not just stop you from receiving a double spend attempt message, but he should also solve the puzzle to create a confirmation block in a reasonable time frame. Currently solving that puzzle with a single computer would take years; at writing time to solve that puzzle a network of thousands dedicated hardware is used, an attacker would require a billionaire investment to replicate that network. Moreover, it would not only need to create one confirmation block but six of them (6 confirmation blocks are required in the Bitcoin network to trust a payment).
Critics of Bitcoin say that all the computation power used to make the Bitcoin network secure is just a waste of energy because there are other reliable and better technologies. Is that true?
  1. What is RaiBlocks? RaiBlocks is a crypto currency that advertises itself as a fast, fee-less and secure currency, unlikely Bitcoin which is currently slow and high-fee (usually requires 1 hour to a full payment confirmation). But the key point is that Bitcoin has been made that way to guarantee his users a certain amount of security to prevent double spendings.
RaiBlocks completely ignores the Bitcoin technology and relies on a special version of the Proof Of Stake concept. When you receive a payment in the RaiBlocks network you have to wait a certain amount of time to be sure that a double spending has not been attempted (and remember the first problem, if an attacker stops you from receiving the double spend you would never know!) When a double spent is detected, the RaiBlocks network starts a vote. Every peer connected to the network vote to accept the payment A or payment B; every user vote is weighted with the amount of his balance. Usually each peer votes for the first transaction he receives. The transaction which the sum of votes reaches the 51% of online amount of currency wins. The winning transaction is accepted by the network and the other one is discarded. (Reference https://github.com/clemahieu/RaiBlocks/wiki/Double-spending-and-confirmation)
The payment receiver, if his network has not been compromised, will then know if he can trust the payment or not, and will ship the good accordingly. This system leads to an unsolvable problem.
  1. The Man in the Middle attack.
If an attacker succeeds to put himself between a merchant and the RaiBlocks network he can just filter the double spending payment packets, and the merchant will never know that he is receiving a double spending. The Raiblocks network will discard that payment while the merchant will accept it.
https://s18.postimg.org/7pnm6yweh/doublespend.png
  1. Solutions proposed by the RaiBlocks team
a) The merchant should ask a vote for each payment he receives and wait for the confirmation. The problem is that the attacker could manipulate the vote by telling the merchant that only his peers are connected to the network thus he will win the vote by filtering only his votes. Plus, asking a vote for each payment would cause a huge increment of bandwidth usage that many peers could not handle.
b) The merchant should have a remote node verifying the payment. The attacker could just attack that network too.
c) The merchant should ask the RaiBlocks.net website if the payment has been accepted. The attacker can hack the RaiBlocks.net website. Also if you have to rely on a website you can no longer consider RaiBlocks a decentralized network.
Other solutions
1) A payment to be accepted should require a vote with a minimum weight quorum. It's difficult to establish a correct quorum, and if that quorum is offline no payments will be processed.
2) A payment need to be accepted by some trusted representatives. This will stop the network on being decentralized. Also, if those representatives are offline the payments are not processed.
  1. Why Bitcoin is not vulnerable to this type of attack Simply because an attacker, to be trusted by a merchant, would require to solve a very difficult puzzle for six times. An attacker cannot alter the difficulty of that puzzle.
  2. Other observations
a) RaiBlocks is just Bitcoins without the Bitcoin securing algorithm. The creator of Bitcoin, Satoshi Nakamoto, describes the double spending problem in the original Bitcoin paper: https://Bitcoin.org/Bitcoin.pdf. The developer of RaiBlocks just thinks to solve the problem by ignoring the problem.
b) The official representatives of the RaiBlocks network own more than 52% of total voting weight, allowing the developer to manipulate every vote on his will. Source: https://dev.RaiBlocks.net/page/representatives.php
  1. References https://RaiBlocks.net/media/RaiBlocks_Whitepaper__English.pdf https://github.com/clemahieu/RaiBlocks/wiki/Double-spending-and-confirmation
submitted by Yyk3 to RaiBlocks [link] [comments]

Why I don’t get The Tangle.

Bitcoin is a distributed system of nodes that creates and maintains an eventually globally-consistent ledger or database (the blockchain) of conforming transactions. In this system a node can infer two things with high probability about any transaction that has been in the blockchain for over about an hour: 1) the transaction is irreversibly part of the ledger, and 2) the transaction conforms to a set of rules including, for example, that it does not double-spend. The Iota Tangle is also a distributed system of nodes that claims to accomplish basically the same as Bitcoin but with a very different underlying technology. However it’s unclear from the whitepaper and other online discussions how it accomplishes this. I’m not questioning the technical details but trying to grasp the general scheme by which the system creates an eventually globally-consistent ledger of conforming transactions. Put aside attack scenarios. Put aside quantum resistance, etc. What I’m saying is, how would you explain this to a 12 year old? This passage is from the whitepaper “The Tangle” by Serguei Popov dated August 22, 2017. It is assumed that the nodes check if the approved transactions are not conflicting. If a node finds that a transaction is in conflict with the tangle history, the node will not approve the conflicting transaction in either a direct or indirect manner(3). (3) If a node issues a new transaction that approves conflicting transactions, then it risks that other nodes will not approve its new transaction, which will fall into oblivion. So how does the approving node detect conflicting transactions. One simple way would be for each node to hold the entire Tangle in local memory and do an exhaustive search. (I’m not even worrying about global-consistency yet.) But the system claims to be designed to handle millions of IoT devices issuing thousands of transactions per day. If a transaction is 100 bytes, for example, then the Tangle will grow by many 100s of gigabytes per day. So this is clearly infeasible. Also, according to the passage and footnote, nodes must also insure that other transactions farther down the chain are also not conflicting. That is, if A approves B, B approves C, C approves D, etc. then all of those transactions must be checked to be conflict-free by the node issuing the new transaction. The other option for detecting conflict would be a distributed search. In this scenario, no node holds the entire Tangle and there is no specially-designated central node which does. A distributed search would also require an exhaustive search of all transactions with the work spread across many nodes. Such a system could probably be designed but it would have to be fantastically complex in order to guarantee that the entire Tangle was searched and in a reasonable time. The coordination required and the vast amount of node-to-node communication would seem to also be infeasible. And I’m still not even worrying about the problem of precisely defining the Tangle as a globally-consistent entity. Conclusion At least for me, the most basic aspects of the Tangle are still a mystery. However, I accept that I may not understand the magic of the Tangle. If that is the case, I would look forward to anyone explaining it to me or referring me to any materials which clearly explain it.
submitted by hxsquid to Iota [link] [comments]

RaiBlocks($XRB) based on vulnerable algorithm?

From: https://bitcointalk.org/index.php?topic=1381323.9700 --Thread [486]
Quote:
Why RaiBlocks is not secure.
In this article I will try to explain why RaiBlocks is not secure and why its technology is any better neither comparable than the Bitcoin technology.
  1. Decentralized payments Decentralized payment networks are, in opposite of centralized payment network like banks, a way to secure your money without having the risk that a central authority could steal your money or manipulate the money in the market. Decentralized payment networks use asymmetric cryptography to ensure that you are the only one who can spend your money. When you create a cryptocurrency wallet you are given a public key and a private key. The public key allows other people to send you money, while the private key allows you to spend them.
But how other users know how many money do you have? To accomplish this, every user of a decentralized payment network must download the entire transaction database which is replicated on the entire network. When you send a payment over the network, it is received by all the users connected on the network allowing them to know your updated wallet balance and allowing them to discard that payment if you don’t own enough funds.
  1. Double Spending The main problem that afflicts decentralized payment networks is double spending: the ability of an user to spend his money multiple times. In the real world, when you pay someone you give him the real cash. In a centralized payment network, like VISA, the central database is updated every time you make a payment, and they will not allow you to spend more money than your balance. In a decentralized payment network what happens if you send the same amount of money on two users of the network in the same time? Since their database takes time to update for a small amount of time they both will receive the payment and accept it. In a later moment, when the network tells them that you double spent your money, they will cancel the payment, this is possible because every payment is broadcasted to the entire network, not only the receiver. Without any other security layer, if a malicious user double spends his money and succeeds to block a payment receiver to know that he sent the same money to someone else (or even better, to another wallet of his own), the payment receiver will accept the payment and ship the good. This is so bad, since even a network connection problem could temporarily lead a payment receiver to undetect double spendings.
  2. The Bitcoin Solution To solve this problem, Bitcoin relays on the fact that after you receive a payment you need to wait a confirmation block, the confirmation block tells you that the payment you have received has been accepted by the entire network and you are allowed to spend it. To create a confirmation block, the miners create a list of all the pending unconfirmed transactions and solve a very difficult mathematical puzzle. The miner who solves the puzzle first, sends the block he found with all the list of confirmed transaction and the solved puzzle to the network, the users of the network will check if the puzzle solution is valid and then reward him with some free coins plus the sum of all the payment fees of each transaction in the block. The miners must create a valid list of payments to be accepted by the network, so double spend attempts are just discarded.
In Bitcoin an attacker, to make a succesful double spending, should not just stop you from receiving a double spend attempt message, but he should also solve the puzzle to create a confirmation block in a reasonable time frame. Currently solving that puzzle with a single computer would take years; at writing time to solve that puzzle a network of thousands dedicated hardware is used, an attacker would require a billionaire investment to replicate that network. Moreover, it would not only need to create one confirmation block but six of them (6 confirmation blocks are required in the Bitcoin network to trust a payment).
Critics of Bitcoin say that all the computation power used to make the Bitcoin network secure is just a waste of energy because there are other reliable and better technologies. Is that true?
  1. What is RaiBlocks? RaiBlocks is a crypto currency that advertises itself as a fast, fee-less and secure currency, unlikely Bitcoin which is currently slow and high-fee (usually requires 1 hour to a full payment confirmation). But the key point is that Bitcoin has been made that way to guarantee his users a certain amount of security to prevent double spendings.
RaiBlocks completely ignores the Bitcoin technology and relies on a special version of the Proof Of Stake concept. When you receive a payment in the RaiBlocks network you have to wait a certain amount of time to be sure that a double spending has not been attempted (and remember the first problem, if an attacker stops you from receiving the double spend you would never know!) When a double spent is detected, the RaiBlocks network starts a vote. Every peer connected to the network vote to accept the payment A or payment B; every user vote is weighted with the amount of his balance. Usually each peer votes for the first transaction he receives. The transaction which the sum of votes reaches the 51% of online amount of currency wins. The winning transaction is accepted by the network and the other one is discarded. (Reference https://github.com/clemahieu/RaiBlocks/wiki/Double-spending-and-confirmation)
The payment receiver, if his network has not been compromised, will then know if he can trust the payment or not, and will ship the good accordingly. This system leads to an unsolvable problem.
  1. The Man in the Middle attack.
If an attacker succeeds to put himself between a merchant and the RaiBlocks network he can just filter the double spending payment packets, and the merchant will never know that he is receiving a double spending. The Raiblocks network will discard that payment while the merchant will accept it.
  1. Solutions proposed by the RaiBlocks team
a) The merchant should ask a vote for each payment he receives and wait for the confirmation. The problem is that the attacker could manipulate the vote by telling the merchant that only his peers are connected to the network thus he will win the vote by filtering only his votes. Plus, asking a vote for each payment would cause a huge increment of bandwidth usage that many peers could not handle.
b) The merchant should have a remote node verifying the payment. The attacker could just attack that network too.
c) The merchant should ask the RaiBlocks.net website if the payment has been accepted. The attacker can hack the RaiBlocks.net website. Also if you have to rely on a website you can no longer consider RaiBlocks a decentralized network.
Other solutions
1) A payment to be accepted should require a vote with a minimum weight quorum. It's difficult to establish a correct quorum, and if that quorum is offline no payments will be processed.
2) A payment need to be accepted by some trusted representatives. This will stop the network on being decentralized. Also, if those representatives are offline the payments are not processed.
  1. Why Bitcoin is not vulnerable to this type of attack Simply because an attacker, to be trusted by a merchant, would require to solve a very difficult puzzle for six times. An attacker cannot alter the difficulty of that puzzle.
  2. Other observations
a) RaiBlocks is just Bitcoins without the Bitcoin securing algorithm. The creator of Bitcoin, Satoshi Nakamoto, describes the double spending problem in the original Bitcoin paper: https://Bitcoin.org/Bitcoin.pdf. The developer of RaiBlocks just thinks to solve the problem by ignoring the problem.
b) The official representatives of the RaiBlocks network own more than 52% of total voting weight, allowing the developer to manipulate every vote on his will. Source: https://dev.RaiBlocks.net/page/representatives.php
  1. References https://RaiBlocks.net/media/RaiBlocks_Whitepaper__English.pdf https://github.com/clemahieu/RaiBlocks/wiki/Double-spending-and-confirmation
/Quote
I'm looking more into validating the claims, but thats a huge issue if true. Converse!
submitted by MrNutty to CryptoCurrency [link] [comments]

Concerning article regarding RaiBlocks.

This keeps getting deleted when I post it. God Damnit mods I just want to discuss it. This is NOT my article but DOES concern me as a bag hodler!
Pulled from official Bitcoin Talk announcement thread. Page 480. Not posting link because it might be what is getting flagged.
Why RaiBlocks is not secure.
In this article I will try to explain why RaiBlocks is not secure and why its technology is any better neither comparable than the Bitcoin technology.
  1. Decentralized payments Decentralized payment networks are, in opposite of centralized payment network like banks, a way to secure your money without having the risk that a central authority could steal your money or manipulate the money in the market. Decentralized payment networks use asymmetric cryptography to ensure that you are the only one who can spend your money. When you create a cryptocurrency wallet you are given a public key and a private key. The public key allows other people to send you money, while the private key allows you to spend them.
But how other users know how many money do you have? To accomplish this, every user of a decentralized payment network must download the entire transaction database which is replicated on the entire network. When you send a payment over the network, it is received by all the users connected on the network allowing them to know your updated wallet balance and allowing them to discard that payment if you don’t own enough funds.
  1. Double Spending The main problem that afflicts decentralized payment networks is double spending: the ability of an user to spend his money multiple times. In the real world, when you pay someone you give him the real cash. In a centralized payment network, like VISA, the central database is updated every time you make a payment, and they will not allow you to spend more money than your balance. In a decentralized payment network what happens if you send the same amount of money on two users of the network in the same time? Since their database takes time to update for a small amount of time they both will receive the payment and accept it. In a later moment, when the network tells them that you double spent your money, they will cancel the payment, this is possible because every payment is broadcasted to the entire network, not only the receiver. Without any other security layer, if a malicious user double spends his money and succeeds to block a payment receiver to know that he sent the same money to someone else (or even better, to another wallet of his own), the payment receiver will accept the payment and ship the good. This is so bad, since even a network connection problem could temporarily lead a payment receiver to undetect double spendings.
  2. The Bitcoin Solution To solve this problem, Bitcoin relays on the fact that after you receive a payment you need to wait a confirmation block, the confirmation block tells you that the payment you have received has been accepted by the entire network and you are allowed to spend it. To create a confirmation block, the miners create a list of all the pending unconfirmed transactions and solve a very difficult mathematical puzzle. The miner who solves the puzzle first, sends the block he found with all the list of confirmed transaction and the solved puzzle to the network, the users of the network will check if the puzzle solution is valid and then reward him with some free coins plus the sum of all the payment fees of each transaction in the block. The miners must create a valid list of payments to be accepted by the network, so double spend attempts are just discarded.
In Bitcoin an attacker, to make a succesful double spending, should not just stop you from receiving a double spend attempt message, but he should also solve the puzzle to create a confirmation block in a reasonable time frame. Currently solving that puzzle with a single computer would take years; at writing time to solve that puzzle a network of thousands dedicated hardware is used, an attacker would require a billionaire investment to replicate that network. Moreover, it would not only need to create one confirmation block but six of them (6 confirmation blocks are required in the Bitcoin network to trust a payment).
Critics of Bitcoin say that all the computation power used to make the Bitcoin network secure is just a waste of energy because there are other reliable and better technologies. Is that true?
  1. What is RaiBlocks? RaiBlocks is a crypto currency that advertises itself as a fast, fee-less and secure currency, unlikely Bitcoin which is currently slow and high-fee (usually requires 1 hour to a full payment confirmation). But the key point is that Bitcoin has been made that way to guarantee his users a certain amount of security to prevent double spendings.
RaiBlocks completely ignores the Bitcoin technology and relies on a special version of the Proof Of Stake concept. When you receive a payment in the RaiBlocks network you have to wait a certain amount of time to be sure that a double spending has not been attempted (and remember the first problem, if an attacker stops you from receiving the double spend you would never know!) When a double spent is detected, the RaiBlocks network starts a vote. Every peer connected to the network vote to accept the payment A or payment B; every user vote is weighted with the amount of his balance. Usually each peer votes for the first transaction he receives. The transaction which the sum of votes reaches the 51% of online amount of currency wins. The winning transaction is accepted by the network and the other one is discarded. (Reference https://github.com/clemahieu/RaiBlocks/wiki/Double-spending-and-confirmation)
The payment receiver, if his network has not been compromised, will then know if he can trust the payment or not, and will ship the good accordingly. This system leads to an unsolvable problem.
  1. The Man in the Middle attack.
If an attacker succeeds to put himself between a merchant and the RaiBlocks network he can just filter the double spending payment packets, and the merchant will never know that he is receiving a double spending. The Raiblocks network will discard that payment while the merchant will accept it.
https://s18.postimg.org/7pnm6yweh/doublespend.png
  1. Solutions proposed by the RaiBlocks team
a) The merchant should ask a vote for each payment he receives and wait for the confirmation. The problem is that the attacker could manipulate the vote by telling the merchant that only his peers are connected to the network thus he will win the vote by filtering only his votes. Plus, asking a vote for each payment would cause a huge increment of bandwidth usage that many peers could not handle.
b) The merchant should have a remote node verifying the payment. The attacker could just attack that network too.
c) The merchant should ask the RaiBlocks.net website if the payment has been accepted. The attacker can hack the RaiBlocks.net website. Also if you have to rely on a website you can no longer consider RaiBlocks a decentralized network.
Other solutions
1) A payment to be accepted should require a vote with a minimum weight quorum. It's difficult to establish a correct quorum, and if that quorum is offline no payments will be processed.
2) A payment need to be accepted by some trusted representatives. This will stop the network on being decentralized. Also, if those representatives are offline the payments are not processed.
  1. Why Bitcoin is not vulnerable to this type of attack Simply because an attacker, to be trusted by a merchant, would require to solve a very difficult puzzle for six times. An attacker cannot alter the difficulty of that puzzle.
  2. Other observations
a) RaiBlocks is just Bitcoins without the Bitcoin securing algorithm. The creator of Bitcoin, Satoshi Nakamoto, describes the double spending problem in the original Bitcoin paper: https://Bitcoin.org/Bitcoin.pdf. The developer of RaiBlocks just thinks to solve the problem by ignoring the problem.
b) The official representatives of the RaiBlocks network own more than 52% of total voting weight, allowing the developer to manipulate every vote on his will. Source: https://dev.RaiBlocks.net/page/representatives.php
  1. References https://RaiBlocks.net/media/RaiBlocks_Whitepaper__English.pdf https://github.com/clemahieu/RaiBlocks/wiki/Double-spending-and-confirmation
submitted by Doziness to CryptoCurrency [link] [comments]

What is Blockchain - YouTube Cost of Risk From All Perspectives Bitcoin For Dummies - YouTube Bitcoin: Beyond The Bubble - Full Documentary - YouTube Panel Discussion - Double-spend Proofs Versus Double-spend Relay

In Bitcoin we’re dealing with UTXOs, and I may send you a UTXO for 2 Bitcoin or I may spend a UTXO 2 Bitcoin with one going to you. And one is changed back to me. And so making sure that that one is change back to me and not changed back to my attacker is really important. And this can be very asymmetric because there, if I have a one Bitcoin UTXO that I need to spend, it’s my only UTXO. Double-spending occurs when an agent can easily conceal or misrepresent information about the recipients of a particular currency unit, and can thus spend currency twice with a low chance of facing the risk posed by the action. The action causes the value of a currency unit to be misplaced among two indistinguishable copies, and can be considered a market failure. A currency system in which ... Double spending attacks on zero-con rmation transactions in Bitcoin were rst analyzed by Karame et al. [1,2]. The authors show that, with some reasonable assumptions and without the need of special computation nor much network overhead, an attacker has a great probability of succeeding with a double spend-ing attack. Moreover, the authors also ... Attempting a double-spend on a network that uses the first-seen principle is very very difficult, much more difficult again if attempted in-store, and with easy detection, attackers also risk prosecution. Bitcoin Cash 0-conf is a genius combination of speed and simplicity. level 2. Redditor for less than 60 days 1 point · 1 month ago. Bitcoin Cash merchants use it for almost every transaction ... Let's build the double-spend alert system on top of Bitcoin, and not ruin a foundational rule that had a clear intention in the original design. Copy link Quote reply Contributor Author dgenr8 commented Jul 15, 2014 @SergioDemianLerner Thank you very much for your attention and thoughts on this. Regarding the attacks 1. and 2. that you posit: Relaying A will not overcome the bloom filter ...

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What is Blockchain - YouTube

This channel offers educational video serios about Bitcoin. Every episode is aiming to address as simple as possible popular bitcoin questions or misconcepti... HIGH-RISK! For demonstration purpose only! Please note that the bot in the Livestream is set to demonstrate insane trading speed. It was NOT tested in long run, and most likely will result in ... Why bitcoin transactions are so slow and why there is a huge risk of double spending? - Duration: 2:53. Bitcoin For Dummies 33,591 views. 2:53. ... Blockchain explained. Shai Rubin, CTO of Citi Innovation Lab, explains in an easy and simple way the basics of blockchain. Risk Management - Cost-Benifit ... Bitcoin Halving News, Anti-Bearish Coalition,Investments Microsoft EU 2,029 watching. Live now ; How I learned To Day Trade In A Week - Duration: 22:58. Garen ...

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