[Freeciv-Dev] Re: Passwd auth with MD5 hash

[Greg Wooledge <greg@xxxxxxxxxxxx>]

Trent Piepho (xyzzy@xxxxxxxxxxxxx) wrote:

> It was in the call to crypt(), except my crypt manpage says it uses a
> variation of DES not md5.  Is crypt() portable to non-UNIX systems though?

> My manpage says that crypt will return a 13 character string, I think that
> it's the two character salt followed by a base64 encoded 64-bit hash value.

MD5 password hash support was bolted on in some of the more recently
developed Unix systems (*BSD, Linux, etc.).  It uses the same call to
crypt(), but the magic "$1$" at the beginning of the salt signifies...
well, you can read for yourself:

       If  the salt starts with $1$ an MD5 based password hashing
       algorithm is applied. The salt should consist off $1$ fol­
       lowed with eight characters.

(That's from the Linux man page.  IIRC, the OpenBSD one is *much* more
thorough, and includes a third hash algorithm as well.)

Needless to say, the presence of an MD5 hash algorithm in crypt() is
*not* very portable even across Unix systems, let alone non-Unix.

-- 
Greg Wooledge                  |   "Truth belongs to everybody."
greg@xxxxxxxxxxxx              |    - The Red Hot Chili Peppers
http://wooledge.org/~greg/     |

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