How To Safely Store A Password
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How To Safely Store A Password
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Re: How To Safely Store A Password
#2I'm not so sure. The other side of the coin is that ``{MD5, SHA1, SHA256, SHA512, SHA-3, etc}'' have had extensive peer review in the cryptography world.
There's a long history of ``clever new ways'' to use existing crypto algorithms turning out to have serious flaws -- a good example is early attempts to improve the strength of (56-bit key) DES by encrypting three times with three keys. This turns out to introduce enough non-randomness to make the result much weaker than one might expect; standard 3DES works by encrypting with the first key, decrypting with the second, and encrypting with the third, which results in very different properties of the output cyphertext.
I'm not saying BCrypt has the same sort of issues, but I'd like to see some cryptanalysis of this before trusting my users' data with it. Notably, there seems to be no links to such analysis on the BCrypt home page -- not even an argument from the author as to why this code should be cryptographically sound.
Re: How To Safely Store A Password
#3I'm not so sure. The other side of the coin is that ``{MD5, SHA1, SHA256, SHA512, SHA-3, etc}'' have had extensive peer review in the cryptography world. There's a long history of ``clever new ways'' to use existing crypto algorithms turning out to have serious flaws -- a good example is early attempts to improve the strength of (56-bit key) DES by encrypting three times with three keys. This turns out to introduce e…
No. Use Bcrypt. Always.
Bcrypt is backed by Blowfish, designed by Bruce Schneier. Go look it/him up. It's secure.
MD5/SHA1/etc are not weak because they are cryptographically weak (though some are), it is weak because they are fast. SHA3, when it is picked, will still be a very bad choice because it too will be fast.
So, why Bcrypt? Well, it uses Blowfish. Blowfish has a very slow key scheduling algorithm which basically involves a lot of hashing to get the round subkeys. Bcrypt makes this even slower. So what? Well, with Bcrypt you could set it up to take .3 seconds to verify a password. Try bruteforcing on that.
Re: How To Safely Store A Password
#4HN, is this the consensus? I thought certain hashes worked fine when properly salted?
Re: How To Safely Store A Password
#5HN, is this the consensus? I thought certain hashes worked fine when properly salted?
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Re: How To Safely Store A Password
#6I'm not so sure. The other side of the coin is that ``{MD5, SHA1, SHA256, SHA512, SHA-3, etc}'' have had extensive peer review in the cryptography world. There's a long history of ``clever new ways'' to use existing crypto algorithms turning out to have serious flaws -- a good example is early attempts to improve the strength of (56-bit key) DES by encrypting three times with three keys. This turns out to introduce e…
No. Use Bcrypt. Always. Bcrypt is backed by Blowfish, designed by Bruce Schneier. Go look it/him up. It's secure. MD5/SHA1/etc are not weak because they are cryptographically weak (though some are), it is weak because they are fast. SHA3, when it is picked, will still be a very bad choice because it too will be fast. So, why Bcrypt? Well, it uses Blowfish. Blowfish has a very slow key scheduling algorithm which basic…
Indeed. Blowfish is also standardized and has withstood peer review, cryptanalysis and has otherwise been baptized by fire. Plus, if it's good enough for people as picky as Theo DeRaadt, it's probably good enough for you.
Re: How To Safely Store A Password
#7HN, is this the consensus? I thought certain hashes worked fine when properly salted?
Yes, this is consensus. "Salting" isn't actually a real security practice. See: http://chargen.matasano.com/chargen/2007/9/7/enough-with-the...
Re: How To Safely Store A Password
#8HN, is this the consensus? I thought certain hashes worked fine when properly salted?
In a case like the Gawker incident, it isn't safe. If the source code to the password hashing algo is compromised (it was) then the salt becomes useless. In short, just use bcrypt.
Re: How To Safely Store A Password
#9HN, is this the consensus? I thought certain hashes worked fine when properly salted?
In a case like the Gawker incident, it isn't safe. If the source code to the password hashing algo is compromised (it was) then the salt becomes useless. In short, just use bcrypt.
No. No no no.
The source code to the hashing algorithm means nothing. It is already open source!
The reason that the salt is there is to prevent against rainbow tables.
The salting did NOT become useless. If they had not salted passwords, then many many more passwords would have been broken because instead of having to brute force each and every one, you'd just look it up in a massively large hash table.
Re: How To Safely Store A Password
#10I'm not so sure. The other side of the coin is that ``{MD5, SHA1, SHA256, SHA512, SHA-3, etc}'' have had extensive peer review in the cryptography world. There's a long history of ``clever new ways'' to use existing crypto algorithms turning out to have serious flaws -- a good example is early attempts to improve the strength of (56-bit key) DES by encrypting three times with three keys. This turns out to introduce e…
"A Future-Adaptable Password Scheme" by Provos and Mazieres.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.80....
An HTML version appears to be here: http://www.usenix.org/event/usenix99/provos/provos_html/node... Some of the links, particularly the main page, appear to be broken.