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> assuming it had transitioned to a better scheme later to avoid collisions attacks Exactly. Collision attacks are fatal to Bitcoin, because they can make it i
by petertodd 6y ago
> assuming it had transitioned to a better scheme later to avoid collisions attacks
Exactly. Collision attacks are fatal to Bitcoin, because they can make it impossible to achieve consensus over what is the valid version of the blockchain data. If you get advanced warning, transition is possible with some caveats. But hoping for advanced warning is risky when money is on the line (collision attacks can even be used to steal money in certain scenarios, eg with certain ways of doing multisig).
> because bitcoin didn't used a brute-force resistant hash function
That's really a topic in of itself. There is no such thing as a non-"brute-force-resistant" PoW function.
- littlestymaar 6y agoCollisions only affect new transactions, they aren't able to tamper with the existing blocks (you need preimage attack for that), and for the record the first collision on md5 only came in 2004 and 2017 for sha1, way after the theoretical vulnerability was proven. There's plenty of time to move from one hashing scheme to another. > There is no such thing as a non-"brute-force-resistant" PoW function. Well, maybe on the semantic debate, but there's a big difference between fast hash functions (sha-2 and the likes) and slow-by-design ones: ASIC.