Comment les algorithmes de consensus de la blockchain peuvent-ils atteindre la finalité ?

I think it is important to understand what finality means and why it is required. The fundamental tenet behind blockchains is - a decentralised system is better than centralised, example "we don't need federal banks to issue currency". It may not be correct but for a moment, assume that it does have value for substantial people. But when we go from centralised to decentralised, how do we know that each node in the network has the same underlying data where they are writing to and reading from. Achieving this is finality. To have this, you need to make it hard to alter what the network has already arrived at. Probabilistic finality is basically improbable but not an impossible way to achieve this to an extent that it is acceptable.

Probabilistic finality describes the consensus algorithm behind PoW (Proof-of-Work). Which is how bitcoin works. It describes that validators of transactions only need to refer back to the longest chain of blocks created, with the longest list of transactions. It takes actual computing power to create new blocks and add it to the chain, so that means that if you follow the longest chain of transactions, that required the most computational work to make. THAT is what we trust. Now that also means that it is very unlikely, or improbably that a transaction was not valid, but the longer the chain is, the less likely an invalid transaction can go through. So chances are for bitcoin is somewhere between 0%, and 0.00001%. But it is not 0.

Blockchain consensus algorithms achieve finality through processes tailored to their design: 1. Proof of Work (PoW): Miners validate transactions via puzzle-solving. 2. Proof of Stake (PoS): Validators propose blocks based on stake. 3. Delegated Proof of Stake (DPoS): Elected delegates validate, enhancing scalability. 4. Practical Byzantine Fault Tolerance (PBFT):Nodes vote for finality in permissioned blockchains. 5. Proof of Authority (PoA): Trusted authority nodes ensure finality based on identity and reputation.

Probabilistic finality, prevalent in proof-of-work (PoW) blockchains like Bitcoin and Ethereum, hinges on the likelihood that a transaction or block won't face overwrite. As more blocks stack atop a confirmed one, the probability of alteration diminishes. Bitcoin, for instance, deems a transaction final after six confirmations, yielding less than a 0.1% chance of reversal. Yet, the inherent nature of probabilistic finality introduces a small but existing risk of forks or reorganizations, injecting uncertainty and potential delays into user and application experiences.

Achieving finality in blockchain consensus algorithms is at the heart of ensuring the integrity and reliability of decentralized systems. The exploration of different approaches, from probabilistic to absolute and hybrid finality, provides a comprehensive understanding of the challenges and innovations in this space. I'm particularly intrigued by the intersection of AI and blockchain in achieving these goals. The continuous evolution of consensus mechanisms is a testament to the dynamism of the blockchain ecosystem. Looking forward to more insightful discussions on the intricacies of achieving finality in consensus algorithms!

Welll,,,, 🚀 Once a supermajority of validators vote and certify a block using Byzantine agreement protocols,,,,,,, it becomes irrevocable, providing high security and efficiency. Users benefit from faster confirmations without concerns about forks or reorganizations. 🔐✨

Absolute finality is achieved by using cryptographic mechanisms, such as digital signatures, verifiable random functions, or threshold encryption, that allow validators to agree on a single block in each round, and to commit to it irrevocably.

Absolute finality offers higher security and efficiency for users and applications, as they do not have to wait for multiple confirmations or worry about forks or reorganizations.

Absolute finality is a way of making sure that some online systems, like Algorand and Polkadot, do not change their records after they are done. These systems use special rules and math to make sure that everyone agrees on the same record, and that no one can change it later. For example, Algorand asks most of the people in the system to vote for a record, and then to sign it with their own code. Absolute finality makes these systems safer and faster for users and apps, as they do not have to wait for more checks or worry about mistakes or changes.

Absolute finality guarantees transactions cannot be reversed once cryptographically committed. This provides higher security for applications, with no need to wait for confirmations. While proof-of-stake algorithms can cryptographically guarantee transactions cannot be reversed, proof-of-work chains remain probabilistic. Ethereum's original PoW design was shown to lack absolute finality when disagreement over the DAO fork led to a permanent Ethereum/Ethereum Classic split. However, new proof-of-stake initiatives like Casper FFG aim to bring stronger finality to Ethereum through validator voting to finalize checkpoints.

Several new and innovative consensus algorithms are constantly being developed to address existing limitations and improve the scalability, security, and efficiency of blockchain networks. Some examples include Proof-of-Elapsed-Time (PoET), Proof-of-Storage (PoS), and newer Byzantine Fault Tolerance (BFT)-based algorithms.

Some blockchains use two different ways to agree on what is true. One way is to use a lot of computing power to make new blocks. This way is not very certain, but it is fast. The other way is to use some people who have a stake in the system to confirm the blocks. This way is very certain, but it is slow. These blockchains use both ways together, so they can have the best of both worlds. They can make new blocks quickly, and then make sure they are true later. This makes the system more secure and efficient.

There are a few prominent blockchain projects leveraging a hybrid proof-of-work (PoW) and proof-of-stake (PoS) consensus model to achieve a balance of security, scalability, and finality: Ethereum 2.0, Polygon, Decred, Cosmos These show that hybrid consensus systems can balance throughput and scalability from PoS while benefiting from the proven security models of PoW chains. Implementations vary depending on which components utilize each algorithm.

Bitcoin's PoW achieves probabilistic finality, which means the more people use bitcoin, the less likely the event of an attack. However, this also means that the more people use it, the less scalable it becomes with limited block space. With PoS and absolute finality, there is a tradeoff here, where it is quicker, and more scalable both in the creation of blocks, and when leaving the computational energy required to add blocks to the chain like in PoW, but less secure or decentralized. The idea of hybrid finality is trying to bring the best of both worlds. As more consensus protocols are coming out, the important thing to know is that all of them have in common that their security increases as users come in called the network effect.

Hybrid finality, exemplified in blockchain marvels like Ethereum 2.0 and Cosmos, orchestrates a symphony of technical prowess by fusing PoW and PoS. This intricate model unfolds through a two-layer consensus algorithm: one layer orchestrates block production, employing PoW or PoS with probabilistic finality, while the second layer, wielding PoS, delivers an absolute finality masterpiece. Ethereum 2.0's Casper, a PoS mechanism, sees validators attesting to PoW-produced blocks, culminating in finalized checkpoints. The hybrid finality paradigm meticulously balances security and scalability, synergizing the strengths of PoW and PoS, ushering in a realm of expedited, dependable transactions and blocks.

Agree that, bigger picture, legal finality is an important consideration. This implicates local bankruptcy laws, and settlement finality regulations if any.

well,,,,, Blockchain consensus algorithms achieve finality through mechanisms like Proof of Work (PoW), Proof of Stake (PoS),,,,,,,,,,,,,,,, or Delegated Proof of Stake (DPoS). 🌐 Once a sufficient number of participants agree on a valid block, it becomes immutable, ensuring finality. ⛓️✅

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Legal finality is what matters, everything else is hubris. Legal Finality can only be provided when contract law (the right to dispute) is not permitted. That requires primary legislation

Finality is an important property of blockchains that determines to secureness and efficiencies. There are 3 types of finality: probabilistic, absolute, and hybrid. Probabilistic finality is based on the probability that a block or a transaction will not be reversed, and is achieved by most PoW blockchains. Absolute finality is based on the guarantee that a block or a transaction is final and irreversible, and is achieved by some PoS blockchains. Hybrid is based on a two-layer consensus algorithm that combines PoW and PoS, and offers a trade-off between security and scalability. Each type of finality has its own advantages and disadvantages, and different blockchains may choose different models depending on their design goals and use cases.