Date: Tue, 15 Nov 2011 06:35:02 +0400 From: Solar Designer <solar@...nwall.com> To: dillon@...llo.backplane.com, Nolan Lum <nol888@...il.com> Cc: oss-security@...ts.openwall.com Subject: weird crypt-sha* in DragonFly BSD Hi, Matthew - when I read that DragonFly moved to using SHA-256 for passwords by default, I thought this was referring to the SHA-256 based flavor of Ulrich Drepper's SHA-crypt. This would not be the best choice to make, in my opinion, but it would not be that bad. However, I just found this: http://gitweb.dragonflybsd.org/dragonfly.git/tree/HEAD:/lib/libcrypt Are these crypt-sha256.c and/or crypt-sha512.c files actually in use? I hope not... They do not include any password stretching, resulting in password hashes that are much quicker to crack than MD5-crypt's. There's also minor weirdness in the code - such as two local pointer variables being declared static seemingly for no reason, and only "final" but not "ctx" being zeroized in the end. But even this lack of proper cleanup is very minor compared to the lack of stretching. Oh, also the "$3$" prefix was apparently previously used for NTLM: http://en.wikipedia.org/wiki/Crypt_(Unix)#NT_Hash_Scheme "FreeBSD used the $3$ prefix for this." http://search.cpan.org/~zefram/Authen-Passphrase/lib/Authen/Passphrase/NTHash.pm "... crypt string must consist of "$3$$" (note the extra "$") followed by the hash in lowercase hexadecimal." BTW, I looked at DragonFly's code while analyzing a more subtle issue with Ulrich's SHA-crypt: http://www.openwall.com/lists/oss-security/2011/11/15/1 I thought that maybe you reimplemented it in a better fashion avoiding that issue, but I found this... %-) Alexander
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