On Sat, 5 Jan 2002, Bill Vermillion wrote:

> Blowfish encrypted:
>
> fp:$2a$04$.d4.6FZpPIj9GC6DRIRDUuJhPWGP059OmLP2IxSgTQ11LWHVGxxbu:1007:1007::0:0:Bogus Name:/home/fp:/bin/ksh93
>
> [...]
>
> So MD5 uses a much larger salt, but blowish generates a much
> long encrypted key, 52 vs 22. I have no docs but >if< the salt is
> only 2 characters in blowfish - assuming it works as does MD5

Use the source Luke! See /usr/src/secure/lib/libcrypt

The "04" in the blowfish password is the number of iterations to
generate the hash (actually on the order of 2^4). The cool thing
is you can change this "on the fly" without having to recompile
libcrypt. Change that and you've just increased the time it would
take to do a dictionary attack. The default (and the minimum) is
4, but could be anything.

The blowfish salt is included in the hash and stops with the 23rd
character. So, the salt above is ".d4.6FZpPIj9GC6DRIRDUuJ" which is
about 16 bytes. The rest is the password hash. So, the blowfish
salt is indeed larger than MD5's, which I believe is only 6 bytes.

-Paul.

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