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, 91 insertions, 0 deletions

diff --git a/common/openpgp-oid.c b/common/openpgp-oid.c
index 19fadd3f2..a1ceba4ef 100644
--- a/common/openpgp-oid.c
+++ b/common/openpgp-oid.c
@@ -1,5 +1,6 @@
 /* openpgp-oids.c - OID helper for OpenPGP
  * Copyright (C) 2011 Free Software Foundation, Inc.
+ * Copyright (C) 2013 Werner Koch
  *
  * This file is part of GnuPG.
  *
@@ -36,6 +37,11 @@
 #include "util.h"
 
 
+/* The OID for Curve Ed25519 in OpenPGP format.  */
+static const char oid_ed25519[] =
+  { 0x0a, 0x2b, 0x06, 0x01, 0x04, 0x01, 0x97, 0x55, 0x01, 0x05, 0x01 };
+
+
 /* Helper for openpgp_oid_from_str.  */
 static size_t
 make_flagged_int (unsigned long value, char *buf, size_t buflen)
@@ -236,3 +242,88 @@ openpgp_oid_to_str (gcry_mpi_t a)
   xfree (string);
   return xtrystrdup ("1.3.6.1.4.1.11591.2.12242973");
 }
+
+
+
+/* Return true if A represents the OID for Ed25519.  */
+int
+openpgp_oid_is_ed25519 (gcry_mpi_t a)
+{
+  const unsigned char *buf;
+  unsigned int nbits;
+  size_t n;
+
+  if (!a || !gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE))
+    return 0;
+
+  buf = gcry_mpi_get_opaque (a, &nbits);
+  n = (nbits+7)/8;
+  return (n == DIM (oid_ed25519)
+          && !memcmp (buf, oid_ed25519, DIM (oid_ed25519)));
+}
+
+
+
+/* Map the Libgcrypt ECC curve NAME to an OID.  If R_NBITS is not NULL
+   store the bit size of the curve there.  Returns NULL for unknown
+   curve names.  */
+const char *
+openpgp_curve_to_oid (const char *name, unsigned int *r_nbits)
+{
+  unsigned int nbits = 0;
+  const char *oidstr;
+
+  if (!name)
+    oidstr = NULL;
+  else if (!strcmp (name, "Ed25519"))
+    {
+      oidstr = "1.3.6.1.4.1.3029.1.5.1";
+      nbits = 255;
+    }
+  else if (!strcmp (name, "nistp256"))
+    {
+      oidstr = "1.2.840.10045.3.1.7";
+      nbits = 256;
+    }
+  else if (!strcmp (name, "nistp384"))
+    {
+      oidstr = "1.3.132.0.34";
+      nbits = 384;
+    }
+  else if (!strcmp (name, "nistp521"))
+    {
+      oidstr = "1.3.132.0.35";
+      nbits = 521;
+    }
+  else
+    oidstr = NULL;
+
+  if (r_nbits)
+    *r_nbits = nbits;
+  return oidstr;
+}
+
+
+/* Map an OpenPGP OID to the Libgcrypt curve NAME.  If R_NBITS is not
+   NULL store the bit size of the curve there.  Returns "?" for
+   unknown curve names.  */
+const char *
+openpgp_oid_to_curve (const char *oid)
+{
+  const char *name;
+
+  if (!oid)
+    name = "";
+  else if (!strcmp (oid, "1.3.6.1.4.1.3029.1.5.1"))
+    name = "Ed25519";
+  else if (!strcmp (oid, "1.2.840.10045.3.1.7"))
+    name = "NIST P-256";
+  else if (!strcmp (oid, "1.3.132.0.34"))
+    name = "NIST P-384";
+  else if (!strcmp (oid, "1.3.132.0.35"))
+    name = "NIST P-521";
+  else /* FIXME: Lookup via Libgcrypt.  */
+    name = "?";
+
+  return name;
+}