gpg: First take on PKT_ENCRYPTED_AEAD.

* common/openpgpdefs.h (PKT_ENCRYPTED_AEAD): New const.
* g10/dek.h (DEK): Increase size of use_aead to 4 bits.
* g10/filter.h (cipher_filter_context_t):  Add new fields for AEAD.
* g10/packet.h (PKT_encrypted): Add fields aead_algo, cipher_algo, and
chunkbyte.
* g10/build-packet.c (do_encrypted_aead): New.
(build_packet): Call it.
* g10/parse-packet.c (dump_sig_subpkt): Handle SIGSUBPKT_PREF_AEAD.
(parse_one_sig_subpkt, can_handle_critical): Ditto.
(parse_encrypted): Clear new PKT_ENCRYPTED fields.
(parse_encrypted_aead): New.
(parse): Call it.
* g10/gpg.c (main): Take care of --rfc4880bis option when checking
compliance.
* g10/cipher-aead.c: Replace the stub by real code.
* g10/decrypt-data.c (decode_filter_ctx_t): Add fields for use with
AEAD.
(aead_set_nonce): New.
(aead_set_ad): New.
(decrypt_data): Support AEAD.
(aead_underflow): New.
(aead_decode_filter): New.
* g10/encrypt.c (use_aead): Make that new fucntion work.
(encrypt_simple): Use default_aead_algo() instead of EAX.
* g10/mainproc.c (proc_encrypted): Support AEAD.
(do_proc_packets): Support PKT_ENCRYPTED_AEAD.
--

This code has seen only a very few manual tests.  Encrypting always
uses a 64k chunks and decryption has not been tested with larger
chunks.  Those small chunks make debugging much faster.

Tests can be done using:

  gpg --rfc4880bis --pinentry-mode=loopback --passphrase abc \
      --force-aead --aead-algo ocb --s2k-mode 0 --cipher AES \
      -v -z 0 --status-fd 2 -c <INFILE >OUTFILE

and

  gpg --rfc4880bis --pinentry-mode=loopback --passphrase=abc \
      --status-fd 2 -v -d <INFILE >OUTFILE

Signed-off-by: Werner Koch <wk@gnupg.org>

1 files changed, 16 insertions, 6 deletions

diff --git a/g10/packet.h b/g10/packet.h
index 894b38946..4d155746e 100644
--- a/g10/packet.h
+++ b/g10/packet.h
@@ -459,12 +459,13 @@ typedef struct {
 typedef struct {
   /* Remaining length of encrypted data. */
   u32  len;
-  /* When encrypting, the first block size bytes of data are random
-     data and the following 2 bytes are copies of the last two bytes
-     of the random data (RFC 4880, Section 5.7).  This provides a
-     simple check that the key is correct.  extralen is the size of
-     this extra data.  This is used by build_packet when writing out
-     the packet's header. */
+  /* When encrypting in CFB mode, the first block size bytes of data
+   * are random data and the following 2 bytes are copies of the last
+   * two bytes of the random data (RFC 4880, Section 5.7).  This
+   * provides a simple check that the key is correct.  EXTRALEN is the
+   * size of this extra data or, in AEAD mode, the length of the
+   * headers and the tags.  This is used by build_packet when writing
+   * out the packet's header. */
   int  extralen;
   /* Whether the serialized version of the packet used / should use
      the new format.  */
@@ -476,6 +477,15 @@ typedef struct {
   /* If 0, MDC is disabled.  Otherwise, the MDC method that was used
      (only DIGEST_ALGO_SHA1 has ever been defined).  */
   byte mdc_method;
+  /* If 0, AEAD is not used.  Otherwise, the used AEAD algorithm.
+   * MDC_METHOD (above) shall be zero if AEAD is used.  */
+  byte aead_algo;
+  /* The cipher algo for/from the AEAD packet.  0 for other encryption
+   * packets. */
+  byte cipher_algo;
+  /* The chunk byte from the AEAD packet.  */
+  byte chunkbyte;
+
   /* An iobuf holding the data to be decrypted.  (This is not used for
      encryption!)  */
   iobuf_t buf;