On Tue 2015-02-17 13:48:26 -0500, Thomas White wrote: > I have a private key I am trying to recover the passphrase hash from > to try and then use in conjunction with another tool (hashcat?) to > recover the passphrase on a GPU cluster I have. > > How would one go about extracting the passphrase hash from the private > key?
This is not how OpenPGP passphrases work. there is no embedded hash of the password. For details about how the password is used to unlock the secret key material, please see: Secret-Key Packet Formats https://tools.ietf.org/html/rfc4880#section-5.5.3 and: Secret-Key Encryption https://tools.ietf.org/html/rfc4880#section-3.7.2.1 and: String-to-key (S2K) specifier types: https://tools.ietf.org/html/rfc4880#section-3.7 In particular: Encryption/decryption of the secret data is done in CFB mode using the key created from the passphrase and the Initial Vector from the packet. You can use pgpdump or gpg --list-packets on your secret key to see what the S2K parameters and IV are, and then test passphrases by generating keys and testing them against encrypted MPI and trailing checksum. This is unlikely to work on your GPU cluster without custom coding. --dkg _______________________________________________ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
