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Comment by tptacek | Hacker News Reader

I've read all your comments on this thread. I'm still unclear on why you think the problem of stretching a low-entropy secret into the high-entropy secret needed for strong cryptography is somehow different from the problem of safely storing a password so that disclosure of the authenticator doesn't directly compromise the password.

At this point, given the content on this thread, it seems that it's been explained clearly enough why salted SHAx is inadequate to that task. Do you still not understand why that is?

Until Windows finally got plugged into the Internet and the weak LANMAN hash became relevant to hackers, nobody used "rainbow tables" to break passwords (classic Unix crypt passwords aren't particularly vulnerable to them, since they're salted). But --- and this is crucial --- everyone cracked Unix password files. All of the original password cracking tools, from Crack through JtR, were designed to quickly crack salted hashes.

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> At this point, given the content on this thread, it seems that it's been explained clearly enough why salted SHAx is inadequate to that task. Do you still not understand why that is?

Don't worry, I understand very well (this is not rocket science :P).

My problem, I think, was an inappropriate attitude toward the realities of stored password hashes on servers, in addition to having read that "scrypt is bad for password storage" (and having misunderstood the "badness" of it). I had read too many articles that treated HASH + SALT as "OK" for servers that stored user passwords, and I hadn't kept fresh in my mind the speed with which these passwords can be cracked today.

For example, take the article I linked to in my reply to pbsd: https://crackstation.net/hashing-security.htm (recently written).

This article, and many many others like it, are written by seemingly reputable people, and yet their attitude is that HASH + SALT is OK for servers. Even though it discusses bcrypt, etc., it frames it as though it's an "optional" hardening technique, and places HASH + SALT under the category of "proper hashing":

https://crackstation.net/hashing-security.htm#properhashing

I haven't seen them called out on it. I agree with you and the others in this thread, that it isn't good advice. If 10-char passwords can be protected better with KDFs, then they should be.

Every article you've read that suggests salted hashes are adequate stored password authenticators is wrong.

I don't know what the "security community" is, but if it has any relation to "the community of people who can speak with any authority on cryptography", let me ruefully assure you that it is much, much smaller than you think it is.

> Every article you've read that suggests salted hashes are adequate stored password authenticators is wrong.

Thanks for making that very clear. :)

Re "security community", sorry, I'd edited that part out before I saw your reply, and replaced it with a call for these posts to be called out for giving bad advice.

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