I tried to crack (brute force) my private SSH key I use, but I couldn’t find a working tool for Windows, so I modified a simple private key cracker done by anonymous@echo.or.id. I also tweaked it a bit, I increased the performance and added a basic benchmark.

Update 19.10.2007: new version (0.3) added, increased performance about 50%.

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ssh-privkey-crack v0.3 made by anonymous@echo.or.id,
enhanced by michu@neophob.com

Usage: ssh-privkey-crack [DSA or RSA private key file] [-v|-q]
-v: verbose mode
-q: quite mode
Example:
$ john-mmx -stdout -incremental | ssh-privkey-crack id_dsa
$ ssh-privkey-crack id_dsa < dictionary

Here is a sample output of a successfully attack:

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ssh-privkey-crack v0.3 made by anonymous@echo.or.id,
enhanced by michu@neophob.com

keyheader:
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,256BD3BB384A1DDC

trying inf keys/s, # of tested keys: 3001.
——————————————————————————- — -
Passphrase match: .
Found password after 0 seconds and 3107 tries.
———————————————————————————- — -

This brute force method is not really fast, I compute about 15’000 keys / s on a P4 (4000 Bogo Mips).