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>

1 files changed, 1 insertions, 1 deletions

diff --git a/agent/agent.h b/agent/agent.h
index c2726bbbc..0dcb20107 100644
--- a/agent/agent.h
+++ b/agent/agent.h
@@ -471,7 +471,7 @@ unsigned long get_standard_s2k_count (void);
 unsigned char get_standard_s2k_count_rfc4880 (void);
 int agent_protect (const unsigned char *plainkey, const char *passphrase,
                    unsigned char **result, size_t *resultlen,
-		   unsigned long s2k_count);
+		   unsigned long s2k_count, int use_ocb);
 int agent_unprotect (ctrl_t ctrl,
                      const unsigned char *protectedkey, const char *passphrase,
                      gnupg_isotime_t protected_at,