4 ms·

Last I checked SHA3-512 is like 4x slower than SHA2-512 on x86.

• throw0101c 3y ago
  And SHA-1 is faster than SHA-2, with MD5 faster than both. But speed isn't the only reason to choose an algorithm.
  • AlexandrB 3y ago
    As a non cryptographer this whole conversation chain has me confused. I though it was desirable for a good hashing algorithm to be slow to make brute force difficult.
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    • Tainnor 3y ago
      That's true for passwords (where you don't really use raw SHA or something, but rather something like bcrypt which is intentionally slow), not necessarily for all uses of passwords. E.g. computing a SHA sum of some binary doesn't need to be slow, it just has to be practically impossible to create a collision (which is what's required of every good cryptographic hash function).
    • oconnor663 3y ago
      Yeah this is a super common point of confusion. You need to worry about slowing down a brute force attacker when you're trying to protect a low-entropy secret, which basically always means user passwords. But when your secrets are big enough, like 128 bits, brute force becomes impossible just by virtue of the size of the search space. So for most cryptographic applications, it's the size of your key (and the fact that your hash or cipher doesn't _leak_ the key) that's protecting you from brute force, not the amount of time a single attempt takes.
    • conradludgate 3y ago
      Yeah SHA3 isn't directly for password hashing. You should use a memory strong PBKDF (password based key derivation function) like Argon2, bcrypt, or scrypt. These functions are all constructions that run the hash many times, so the underlying hash speed is irrelevant For high entropy inputs, like for a HMAC signature, you want the hash to be fast because its practically impossible to brute force the 256bit input key, and you often apply this to large inputs.
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  • vlovich123 3y ago
    SHA-2 is has more reliable HW acceleration from what I’ve seen. SHA-1 SW according to smhasher is 350mib/s as is MD5, so never use MD5 as SHA-1 is always stronger (sha2 supposedly is 150mib/s). Hw accelerated SHA-1 and SHA-2 are both ~1.5 Gib/s and on x86 HW acceleration is always available. Blake3 is the most interesting because it’s competitive with SHA2 even without HW acceleration. I wonder how it would fare with HW acceleration.
    • throw0101c 3y ago
      > Blake3 is the most interesting […] Not really? SHA-2 was released in 2001: * https://en.wikipedia.org/wiki/SHA-2 https://en.wikipedia.org/wiki/SHA-2 Blake3 was released 2020. I'm sure if the folks that created SHA-2 did a hash in 2020 they could do something better/faster as well.
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      • vlovich123 3y ago
        First, each Blake version was written by a totally different authors AFAICT so while each version is faster, making a faster construction was a totally different team. I don't see why you're putting so much confidence that the original SHA-2 team could come up with a faster hash function. FWIW, SHA-3 is slower than SHA-2 although of course SHA-3 is a totally different construction from SHA-2 by design.
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