I have a file I encrypted with PGP in 2003. It contains some personal data I'd like to regain access to. I have vague idea of the password, but not enough to successfully guess; but I know its complexity is low. I estimate that search space is on the order of 1e9 and that I need to be able to try about 1000 passwords per second to have chance of cracking it in reasonable timeframe (less than year). Pgpdump says:
$ pgpdump myfile.tar.pgp Old: Symmetrically Encrypted Data Packet(tag 9)(7267297 bytes) Encrypted data [sym alg is IDEA, simple string-to-key]
Trivial approach with repeatedly invoking gnupg is far too slow (about 1 password per second). I would welcome some ideas how to approach this problem, or even better, if some tools to help with this exist.
My current thinking is to piece together my own decrypter code from PGP 2.6.3 source, but that would be quite a project, especially as I am not proficient with C.
Thanks to @dave_thompson_085 for pointing out that there is in fact a way to check if the supplied password is correct (sort of). Unfortunately, it's only a 16 bits, so it inevitably will run into collisions (I actually found one before), passwords that will be accepted, but won't result in correct decryption.