agent: Implement new protection mode openpgp-s2k3-ocb-aes.
* agent/protect.c (agent_protect): Add arg use_ocb. Change all caller to pass -1 for default. * agent/protect-tool.c: New option --debug-use-ocb. (oDebugUseOCB): New. (opt_debug_use_ocb): New. (main): Set option. (read_and_protect): Implement option. * agent/protect.c (OCB_MODE_SUPPORTED): New macro. (PROT_DEFAULT_TO_OCB): New macro. (do_encryption): Add args use_ocb, hashbegin, hashlen, timestamp_exp, and timestamp_exp_len. Implement OCB. (agent_protect): Change to support OCB. (do_decryption): Add new args is_ocb, aadhole_begin, and aadhole_len. Implement OCB. (merge_lists): Allow NULL for sha1hash. (agent_unprotect): Change to support OCB. (agent_private_key_type): Remove debug output.
Instead of using the old OpenPGP way of appending a hash of the
plaintext and encrypt that along with the plaintext, the new scheme
uses a proper authenticated encryption mode. See keyformat.txt for a
description. Libgcrypt 1.7 is required.
This mode is not yet enabled because there would be no way to return
to an older GnuPG version. To test the new scheme use
gpg-protect-tool:
./gpg-protect-tool -av -P abc -p --debug-use-ocb <plain.key >prot.key
./gpg-protect-tool -av -P abc -u <prot.key
Any key from the private key storage should work.
- Signed-off-by: Werner Koch <wk@gnupg.org>