3 ms·
I think they're talking about entropy per bit. If they hash to 64 bytes, they integrate all of the entropy of the password, if they truncate to 72 bytes, they t
by microcolonel 10y ago
I think they're talking about entropy per bit. If they hash to 64 bytes, they integrate all of the entropy of the password, if they truncate to 72 bytes, they throw away all entropy past 72 bytes. This could be a huge problem if you're one of those people who uses a common prefix with a suffix as their password pattern for passwords they need to remember.
- Dylan16807 10y agoEspecially if your password has a lot of words, you have a very low entropy per byte. It's not the worst thing in the world at 72 bytes, but if you were choosing between a 16 byte hash of a sentence and an 18 byte truncation, the hash is going to have vastly more entropy. And 512 bits is more than plenty.
- spronkey 10y ago> And 512 bits is more than plenty. Famous last words.
- Dylan16807 10y ago"A typical supernova releases something like 1051 ergs. (About a hundred times as much energy would be released in the form of neutrinos, but let them go for now.) If all of this energy could be channeled into a single orgy of computation, a 219-bit counter could be cycled through all of its states." You're not getting through 512 bits of entropy unless your cryptographic methods are severely broken, so broken that having more bits would not meaningfully help.