4 ms·
SHA-2 of vulnerable to length extension attacks. SHA2 is vulnerable to length extension attacks the same way as bread is vulnerable to being buttered. If you'
by cperciva 9y ago
SHA-2 of vulnerable to length extension attacks.
SHA2 is vulnerable to length extension attacks the same way as bread is vulnerable to being buttered. If you're using bread and you're worried about buttering, you fundamentally misunderstand what bread is.
- baby 9y agoI think you lost everyone here :D
- krakensden 9y agoHash functions have a pigeonhole principle problem, but that is also the point.
- cperciva 9y agoIf length extension attacks are a problem, you're using a hash function for something which a hash function is not intended to be used for; you probably wanted a MAC instead.
- deleted 9y ago[deleted]
- 15155 9y agoWhy must MAC mean "HMAC RFC2104?"
- cperciva 9y agoIt doesn't. I said MAC, not HMAC.
- baby 9y ago1. Yes. And people do that. I'm nkt talking about me. I'm talking about things I see in my work (I'm a consultant). 2. People should be able to do that. If you're expecting your hash function to behave somehow like a random oracle there is no reason that h(key|data) doesn't work. I see people using sha-2 to derive keys all the time. Even this is unsafe depending on how you do it.