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I thought HashPump could be used for hash length extension attacks. https://github.com/bwall/HashPump https://github.com/bwall/HashPump It's a nice post never
by shin_lao 13y ago
I thought HashPump could be used for hash length extension attacks.
https://github.com/bwall/HashPump https://github.com/bwall/HashPump
It's a nice post nevertheless and another reason to use HMAC instead of custom MAC (nota bene: SHA-3 is not vulnerable to this attack).
- mooism2 13y agoCould you clarify please: is SHA-3 known to not be vulnerable to this attack, or merely not known to be vulnerable to this attack?
- ghshephard 13y agoCourtesy of tptacek, https://news.ycombinator.com/item?id=5776044 https://news.ycombinator.com/item?id=5776044 "Most are vulnerable to length extension attacks. SHA3 (Ketchup) is not vulnerable to length extension attacks, because resistance to length extension was a design criteria for the SHA3 contest."
- Strilanc 13y agoSHA1 is vulnerable because the entire internal state of the hash function is used as the output. This allows you to 'keep going' and extend what was hashed. SHA-3 is not vulnerable because it only uses a subset of the internal state as the output (256 output vs 1600 internal). You can't keep going because you're missing the necessary state.