I had this problem too a while back. The error message: "Generic crypt (3) module: hash encoding string length x, type id y appears to be unsupported on this system" refers to the crypt function not being present on the system or JTR 1.7.6 and above was compiled without crypt being present on the system. I was unable to crack SHA-512 passwords with JTR 1.7.6 and above until I installed the crypt package on my Backtrack 4 system by typing:
apt-get install mcrypt
and then recompiling JTR with the crypt support. Once that was done I was able to successfully crack SHA-512 passwords:
root@bt:/tmp/john-1.7.8/run# cat sha512.txt
$6$zWwwXKNj$gLAOoZCjcr8p/.VgV/FkGC3NX7BsXys3KHYePfuIGMNjY83dVxugPYlxVg/evpcVEJLT/rSwZcDMlVVf/bhf.1
root@bt:/tmp/john-1.7.8/run# ./john sha512.txt
Loaded 1 password hash (generic crypt(3) [?/32])
No password hashes left to crack (see FAQ)
root@bt:/tmp/john-1.7.8/run# ./john --show sha512.txt
?:password
1 password hash cracked, 0 left
I usually apply the Jumbo patch to JTR which provides support for many more hash and cipher types, now includes Winzip password cracking which I want to play around with. The Jumbo patch is available for download here:
http://www.openwall.com/john/g/john-1.7.8-jumbo-2.diff.gz Instructions on how to apply the Jumbo patch are available here:
http://openwall.info/wiki/john/how-to-extract-tarballs-and-apply-patchesPasswords that are a SHA-512 hash, start with $6$ (86 characters)
Default password hashing method for Ubuntu Linux
SHA-256 hashes start with $5$ (43 Characters)
MD5 hashes start with $1$ (22 characters)
Blowfish hashes start with $2$ or $2a$ (depending on the variant used)