Re: Password hashing

2007-10-18 Thread Tero Kivinen
Joseph Ashwood writes: On NetBSD HMAC-SHA1: There is a shortcut in the design as listed, using the non-changing password as the key allows for the optimization that a single HMAC can be keyed, then copied and reused with each seed. this shortcut actually speeds attack by a factor of 3. The

Re: Password hashing

2007-10-18 Thread Peter Gutmann
Martin James Cochran [EMAIL PROTECTED] writes: This might work, although 90% of the steps seem to unnecessarily (and perilously) complicate the algorithm. What's wrong with starting with input SALT || PASSWORD and iterating N times, where N is chosen (but variable) to make brute-force attacks

Re: Password hashing

2007-10-18 Thread Leichter, Jerry
| ... What's wrong with starting | with input SALT || PASSWORD and iterating N times, | | Shouldn't it be USERID || SALT || PASSWORD to guarantee that if | two users choose the same password they get different hashes? | It looks to me like this wold make dictionary attacks harder too. As

Re: Password hashing

2007-10-18 Thread Joseph Ashwood
- Original Message - From: Tero Kivinen [EMAIL PROTECTED] Sent: Monday, October 15, 2007 5:47 AM Subject: Re: Password hashing Joseph Ashwood writes: On NetBSD HMAC-SHA1: There is a shortcut in the design as listed, using the non-changing password as the key allows

Re: Password hashing

2007-10-13 Thread Joseph Ashwood
Just combining several of my thoughts into a single email. On the Red Hat proposal: Why does every undereducated person believe that complexity==security? It is far better to rely on little things called proofs. There are several proofs out there with significant impact on this. In particular

Re: Password hashing

2007-10-13 Thread Ben Laurie
Steven M. Bellovin wrote: On Thu, 11 Oct 2007 22:19:18 -0700 james hughes [EMAIL PROTECTED] wrote: A proposal for a new password hashing based on SHA-256 or SHA-512 has been proposed by RedHat but to my knowledge has not had any rigorous analysis. The motivation for this is to replace MD-5

Re: Password hashing

2007-10-13 Thread Joseph Ashwood
- Original Message - From: Jim Gellman [EMAIL PROTECTED] To: Joseph Ashwood [EMAIL PROTECTED] Cc: Cryptography cryptography@metzdowd.com Sent: Saturday, October 13, 2007 1:25 PM Subject: Re: Password hashing I'm not sure I follow your notation. Are you saying that IV[n] is the n'th

Re: Password hashing

2007-10-13 Thread lists
This does not extend the discussion at hand, but it might be useful to some here who may have to deal with FIPS 140-2. On 13 Oct 2007 09:32:44 +1000, Damien Miller wrote: Some comments: * Use of an off-the-shelf algorithm like SHA1 might be nice for tick here for FIPS certification, but

Re: Password hashing

2007-10-12 Thread james hughes
I forgot to add the links... http://people.redhat.com/drepper/sha-crypt.html http://people.redhat.com/drepper/SHA-crypt.txt On Oct 11, 2007, at 10:19 PM, james hughes wrote: A proposal for a new password hashing based on SHA-256 or SHA-512 has been proposed by RedHat but to my

Re: Password hashing

2007-10-12 Thread Steven M. Bellovin
On Thu, 11 Oct 2007 22:19:18 -0700 james hughes [EMAIL PROTECTED] wrote: A proposal for a new password hashing based on SHA-256 or SHA-512 has been proposed by RedHat but to my knowledge has not had any rigorous analysis. The motivation for this is to replace MD-5 based password hashing at

Re: Password hashing

2007-10-12 Thread Adam Back
I would have thought PBKDF2 would be the obvious, standardized (PKCS #5 / RFC 2898) and designed for purpose method to derive a key from a password. PBKDF2 would typically be based on HMAC-SHA1. Should be straight-forward to use PBKDF2 with HMAC-SHA-256 instead for larger key sizes, or for