Re:Choosing a hash function for 2030 and beyond: SHA-2 vs. S...
by amluto on Tuesday November 25, 2025 @12:17PM
(#46048073)
Collision resistance implies second-preimage resistance, but second-preimage resistance does not imply collision resistance.
Some care is needed with the definitions. For any hash function, the adversary can compute a bunch of hashes, and those outputs obviously have known first preimages. And a hash function with a known collision has a known second preimage given one of the colliding inputs.
Some care is needed with the definitions. For any hash function, the adversary can compute a bunch of hashes, and those outputs obviously have known first preimages. And a hash function with a known collision has a known second preimage given one of the colliding inputs.