Author: Ashley Holman 2014-06-03 15:12:12
Published on: 2014-06-03T15:12:12+00:00
The possibility of SHA-256 being broken and its implications for Bitcoin were discussed in a post from Satoshi on bitcointalk.org. If the breakdown happened gradually, an orderly transition to a new hash function would be possible with software programmed to begin using the new hash after a certain block number. In case of a sudden breakdown, an agreement would have to be reached regarding the honest blockchain before the trouble started, and from there, a new hash function could be used. Ethan Heilman argued that an attack on the mining difficulty algorithm wouldn't necessarily imply the violation of typical security properties of a cryptographic hash function. If a method was discovered that made it easier to discover new blocks, the miners would need to switch to new ASICs and the hash function could be changed without resistance. However, if the attack was so bad that difficulty couldn't scale, and they ran out of leading zeros, then the SHA256 collision resistance would be broken.Luke Dashjr pointed out that if SHA256d was broken, Bitcoin failed entirely. The possibility of fabricating past blocks entirely was also discussed. If the Bitcoin community wanted to switch to a new hash function, one way to do this would be to require miners to find two blocks, one computed using SHA256 and the other computed using the new hash function. This would allow miners a semi-predicable roadmap to shift their infrastructure away from SHA256.
Updated on: 2023-06-08T23:33:16.809130+00:00