gpg: Rework ECC support and add experimental support for Ed25519.

* agent/findkey.c (key_parms_from_sexp): Add algo name "ecc".
(agent_is_dsa_key): Ditto.
(agent_is_eddsa_key): New.  Not finished, though.
* agent/pksign.c (do_encode_eddsa): New.
(agent_pksign_do): Use gcry_log_debug functions.
* agent/protect.c (agent_protect): Parse a flags parameter.
* g10/keygen.c (gpg_curve_to_oid): Move to ...
* common/openpgp-oid.c (openpgp_curve_to_oid): here and rename.
(oid_ed25519): New.
(openpgp_oid_is_ed25519): New.
(openpgp_oid_to_curve): New.
* common/t-openpgp-oid.c (test_openpgp_oid_is_ed25519): New.
* g10/build-packet.c (gpg_mpi_write): Write the length header also for
opaque MPIs.
(gpg_mpi_write_nohdr): New.
(do_key): Use gpg_mpi_write_nohdr depending on algorithm.
(do_pubkey_enc): Ditto.
* g10/ecdh.c (pk_ecdh_encrypt_with_shared_point): Use
gpg_mpi_write_nohdr.
* g10/export.c (transfer_format_to_openpgp):
* g10/keygen.c (ecckey_from_sexp): Return the error.
(gen_ecc): Repalce arg NBITS by CURVE.
(read_parameter_file): Add keywords "Key-Curve" and "Subkey-Curve".
(ask_curve): New.
(generate_keypair, generate_subkeypair): Use ask_curve.
(do_generate_keypair): Also pass curve name.
* g10/keylist.c (list_keyblock_print, list_keyblock_colon): Print
curve name.
* g10/parse-packet.c (mpi_read): Remove workaround for
Libcgrypt < 1.5.
(parse_key): Fix ECC case.  Print the curve name.
* g10/pkglue.c (mpi_from_sexp): Rename to get_mpi_from_sexp.
(pk_verify, pk_check_secret_key): Add special case for Ed25519.
* g10/seskey.c (encode_md_value): Ditto.
* g10/sign.c (do_sign, hash_for, sign_file): Ditto.
--

Be warned that this code is subject to further changes and that the
format will very likely change before a release.  There are also known
bugs and missing code.

Signed-off-by: Werner Koch <[email protected]>

1 files changed, 40 insertions, 3 deletions

diff --git a/g10/build-packet.c b/g10/build-packet.c
index 159b783ed..6681b3429 100644
--- a/g10/build-packet.c
+++ b/g10/build-packet.c
@@ -166,9 +166,14 @@ gpg_mpi_write (iobuf_t out, gcry_mpi_t a)
     {
       unsigned int nbits;
       const void *p;
+      unsigned int lenhdr[2];
 
       p = gcry_mpi_get_opaque (a, &nbits);
-      rc = iobuf_write (out, p, (nbits+7)/8);
+      lenhdr[0] = nbits >> 8;
+      lenhdr[1] = nbits;
+      rc = iobuf_write (out, lenhdr, 2);
+      if (!rc)
+        rc = iobuf_write (out, p, (nbits+7)/8);
     }
   else
     {
@@ -191,6 +196,29 @@ gpg_mpi_write (iobuf_t out, gcry_mpi_t a)
 }
 
 
+/*
+ * Write an opaque MPI to the output stream without length info.
+ */
+gpg_error_t
+gpg_mpi_write_nohdr (iobuf_t out, gcry_mpi_t a)
+{
+  int rc;
+
+  if (gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE))
+    {
+      unsigned int nbits;
+      const void *p;
+
+      p = gcry_mpi_get_opaque (a, &nbits);
+      rc = iobuf_write (out, p, (nbits+7)/8);
+    }
+  else
+    rc = gpg_error (GPG_ERR_BAD_MPI);
+
+  return rc;
+}
+
+
 /* Calculate the length of a packet described by PKT.  */
 u32
 calc_packet_length( PACKET *pkt )
@@ -302,7 +330,11 @@ do_key (iobuf_t out, int ctb, PKT_public_key *pk)
 
   for (i=0; i < npkey; i++ )
     {
-      err = gpg_mpi_write (a, pk->pkey[i]);
+      if ((pk->pubkey_algo == PUBKEY_ALGO_ECDSA && (i == 0))
+          || (pk->pubkey_algo == PUBKEY_ALGO_ECDH) && (i == 0 || i == 2))
+        err = gpg_mpi_write_nohdr (a, pk->pkey[i]);
+      else
+        err = gpg_mpi_write (a, pk->pkey[i]);
       if (err)
         goto leave;
     }
@@ -473,7 +505,12 @@ do_pubkey_enc( IOBUF out, int ctb, PKT_pubkey_enc *enc )
     write_fake_data( a, enc->data[0] );
 
   for (i=0; i < n && !rc ; i++ )
-    rc = gpg_mpi_write (a, enc->data[i]);
+    {
+      if (enc->pubkey_algo == PUBKEY_ALGO_ECDH && i == 1)
+        rc = gpg_mpi_write_nohdr (a, enc->data[i]);
+      else
+        rc = gpg_mpi_write (a, enc->data[i]);
+    }
 
   if (!rc)
     {