Qu'est-ce qu'une fourche dure dans la blockchain? Comment se fait-il qu’il y ait un risque d’une attaque par rejeu lors d’un affrontement difficile?

शुभम् पाठक (Shubham Pathak)

शुभम् पाठक (Shubham Pathak), Entrepreneur,Web Developer,Digital Marketing,IOT at GLOBAL TECHNOLOGY SOLUTIONS HALDWANI (2016-present)

Répondu il y a 50w

As it relates to blockchain technology, a hard fork (or sometimes hardfork) is a radical change to the protocol that makes previously invalid blocks/transactions valid (or vice-versa), and as such requires all nodes or users to upgrade to the latest version of the protocol software.

Qu'est-ce que c'est? A hard fork is a software upgrade that introduces a new rule to the network that isn't compatible with the older software. You can think of a hard fork as an expansion of the rules. (A new rule that allows block size to be 2MB instead of 1MB would require a hard fork).

A hard fork can be implemented to correct important security risks found in older versions of the software, to add new functionality, or to reverse transactions (as in the case with the hard fork to reverse the hack on the DAO (decentralized autonomous organization) in the Ethereum blockchain).

Qu'est-ce qui peut mal tourner? The problem comes when some sort of political impasse arises, and a portion of the community decides to stick by the old rules no matter what. The hash rate, or network computing power, behind the old chain is irrelevant. What matters is that its data (and ruleset) is still perceived to have value, meaning miners still want to mine a chain and developers still want to support it.

The ethereum DAO fourche dur was a perfect case study of how a community can split over rules. Now, we have two blockchains using a variant of the software – ethereum and ethereum classic, both of which boast a different ethos and a different currency.

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the next SegWit2x hard fork is scheduled on 16 november 2017.

A Short Guide to Bitcoin Forks - CoinDesk

Admir Tulic

Admir Tulic, Content Manager sur un nouveau marché décentralisé Accept.io

Répondu il y a 50w · L'auteur dispose de réponses 253 et de vues de réponses 1.6m

A “fork” is a change to the software of the digital currency that creates two separate versions of the blockchain with a shared history.

Forks can be temporary, lasting for a few minutes, or can be a permanent split in the network creating two separate versions of the blockchain. When this happens, two different digital currencies are also created.

A fourche dur is a software upgrade that introduces a new rule to the network that isn't compatible with the older software. You can think of a hard fork as an expansion of the rules. (A new rule that allows block size to be 2MB instead of 1MB would require a hard fork).

More details - click here.

Bharat Mallapur

Bharat Mallapur, Building DApps on Blockchain

Répondu il y a 50w

Thanks Shubham Pathak for asking me to answer this question.

Shubham and others have already explained in good detail what a hard fork means.

However, the question also asks about replay attacks, and I hope the below points (not my own content, source credits at bottom of answer) help clarify this part of the question

Most hard forks have a pre-decided way to stop replay attacks once the hard fork happens successfully. This wasn’t always the case, but after a few cases of replay attacks, nowadays it is taken into consideration when the community first contemplates a hard fork.

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There are two types of replay protections : Strong replay protection (compulsory), or opt-in replay protection which you have to choose to activate.

Strong 2-way replay protection means that transactions from chain X are never valid on chain Y after the hard fork and vice-versa. That is, all transactions have some marker that makes it clear what chain they were intended for.

Bitcoin Cash achieved this through marking the signatures, which every transaction requires. This made transactions on their chain invalid on Bitcoin and vice-versa. This is called “strong” replay protection because there is no way for anyone to accidentally be exposed to replay attacks. Strong replay protection is a lot like an automatically locking door that prevents the transaction from escaping chain X.

Opt-in replay protection means that transactions from chain X need to do something special to be invalid on chain Y. That is, by default, transactions are exposed to replay attacks, but if you manipulate your transaction in a certain way, the transaction won’t be valid on chain Y. Opt-in replay protection is more like a door you have to remember to lock, because otherwise the transaction may escape chain X and get into chain Y.

La source: How Segwit2x Replay Protection Works – Bitcoin Tech Talk

J'espère que cette info vous aide.

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