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Re: [TLS] Working Group Last Call for draft-ietf-tls-pwd

CodesInChaos <codesinchaos@gmail.com> Tue, 03 December 2013 12:19 UTC

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Date: Tue, 03 Dec 2013 13:19:18 +0100
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From: CodesInChaos <codesinchaos@gmail.com>
To: Dan Harkins <dharkins@lounge.org>
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Cc: tls@ietf.org
Subject: Re: [TLS] Working Group Last Call for draft-ietf-tls-pwd
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The protocol uses a fast hash to hash the password.
The challenge-response nature of the protocol means that the sever
cannot apply additional hashing.
This implies that the server needs to store a badly hashed password
which is easy to crack
when the database is compromised. While the information on the wire
doesn't enable an offline dictionary attack,
database leaks are common. So being strong against those attacks is important.

Why did you use a fast hash like HMAC-SHA-256 over a proper password
hash like PBKDF2-HMAC-SHA-256?

Why does the security considerations section not mention password
guessing attacks / offline dictionary attacks against a compromised
database?

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