Refactor the ECC code into 3 files.

* cipher/ecc-common.h, cipher/ecc-curves.c, cipher/ecc-misc.c: New.
* cipher/Makefile.am (EXTRA_libcipher_la_SOURCES): Add new files.
* configure.ac (GCRYPT_PUBKEY_CIPHERS): Add new .c files.
* cipher/ecc.c (curve_aliases, ecc_domain_parms_t, domain_parms)
(scanval): Move to ecc-curves.c.
(fill_in_curve): Move to ecc-curve.c as _gcry_ecc_fill_in_curve.
(ecc_get_curve): Move to ecc-curve.c as _gcry_ecc_get_curve.
(_gcry_mpi_ec_ec2os): Move to ecc-misc.c.
(ec2os): Move to ecc-misc.c as _gcry_ecc_ec2os.
(os2ec): Move to ecc-misc.c as _gcry_ecc_os2ec.
(point_set): Move as inline function to ecc-common.h.
(_gcry_ecc_curve_free): Move to ecc-misc.c as _gcry_ecc_curve_free.
(_gcry_ecc_curve_copy): Move to ecc-misc.c as _gcry_ecc_curve_copy.
(mpi_from_keyparam, point_from_keyparam): Move to ecc-curves.c.
(_gcry_mpi_ec_new): Move to ecc-curves.c.
(ecc_get_param): Move to ecc-curves.c as _gcry_ecc_get_param.
(ecc_get_param_sexp): Move to ecc-curves.c as _gcry_ecc_get_param_sexp.

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

1 files changed, 731 insertions, 0 deletions

diff --git a/cipher/ecc-curves.c b/cipher/ecc-curves.c
new file mode 100644
index 00000000..e813b6b4
--- /dev/null
+++ b/cipher/ecc-curves.c
@@ -0,0 +1,731 @@
+/* ecc-curves.c  -  Elliptic Curve parameter mangement
+ * Copyright (C) 2007, 2008, 2010, 2011 Free Software Foundation, Inc.
+ * Copyright (C) 2013 g10 Code GmbH
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include "g10lib.h"
+#include "mpi.h"
+#include "context.h"
+#include "ec-context.h"
+#include "ecc-common.h"
+
+
+/* This tables defines aliases for curve names.  */
+static const struct
+{
+  const char *name;  /* Our name.  */
+  const char *other; /* Other name. */
+} curve_aliases[] =
+  {
+    { "NIST P-192", "1.2.840.10045.3.1.1" }, /* X9.62 OID  */
+    { "NIST P-192", "prime192v1" },          /* X9.62 name.  */
+    { "NIST P-192", "secp192r1"  },          /* SECP name.  */
+    { "NIST P-192", "nistp192"   },          /* rfc5656.  */
+
+    { "NIST P-224", "secp224r1" },
+    { "NIST P-224", "1.3.132.0.33" },        /* SECP OID.  */
+    { "NIST P-224", "nistp224"   },          /* rfc5656.  */
+
+    { "NIST P-256", "1.2.840.10045.3.1.7" }, /* From NIST SP 800-78-1.  */
+    { "NIST P-256", "prime256v1" },
+    { "NIST P-256", "secp256r1"  },
+    { "NIST P-256", "nistp256"   },          /* rfc5656.  */
+
+    { "NIST P-384", "secp384r1" },
+    { "NIST P-384", "1.3.132.0.34" },
+    { "NIST P-384", "nistp384"   },          /* rfc5656.  */
+
+    { "NIST P-521", "secp521r1" },
+    { "NIST P-521", "1.3.132.0.35" },
+    { "NIST P-521", "nistp521"   },          /* rfc5656.  */
+
+    { "brainpoolP160r1", "1.3.36.3.3.2.8.1.1.1" },
+    { "brainpoolP192r1", "1.3.36.3.3.2.8.1.1.3" },
+    { "brainpoolP224r1", "1.3.36.3.3.2.8.1.1.5" },
+    { "brainpoolP256r1", "1.3.36.3.3.2.8.1.1.7" },
+    { "brainpoolP320r1", "1.3.36.3.3.2.8.1.1.9" },
+    { "brainpoolP384r1", "1.3.36.3.3.2.8.1.1.11"},
+    { "brainpoolP512r1", "1.3.36.3.3.2.8.1.1.13"},
+
+    { NULL, NULL}
+  };
+
+
+typedef struct
+{
+  const char *desc;           /* Description of the curve.  */
+  unsigned int nbits;         /* Number of bits.  */
+  unsigned int fips:1;        /* True if this is a FIPS140-2 approved curve. */
+  const char *p;              /* Order of the prime field.  */
+  const char *a, *b;          /* The coefficients. */
+  const char *n;              /* The order of the base point.  */
+  const char *g_x, *g_y;      /* Base point.  */
+} ecc_domain_parms_t;
+
+
+/* This static table defines all available curves.  */
+static const ecc_domain_parms_t domain_parms[] =
+  {
+    {
+      "NIST P-192", 192, 1,
+      "0xfffffffffffffffffffffffffffffffeffffffffffffffff",
+      "0xfffffffffffffffffffffffffffffffefffffffffffffffc",
+      "0x64210519e59c80e70fa7e9ab72243049feb8deecc146b9b1",
+      "0xffffffffffffffffffffffff99def836146bc9b1b4d22831",
+
+      "0x188da80eb03090f67cbf20eb43a18800f4ff0afd82ff1012",
+      "0x07192b95ffc8da78631011ed6b24cdd573f977a11e794811"
+    },
+    {
+      "NIST P-224", 224, 1,
+      "0xffffffffffffffffffffffffffffffff000000000000000000000001",
+      "0xfffffffffffffffffffffffffffffffefffffffffffffffffffffffe",
+      "0xb4050a850c04b3abf54132565044b0b7d7bfd8ba270b39432355ffb4",
+      "0xffffffffffffffffffffffffffff16a2e0b8f03e13dd29455c5c2a3d" ,
+
+      "0xb70e0cbd6bb4bf7f321390b94a03c1d356c21122343280d6115c1d21",
+      "0xbd376388b5f723fb4c22dfe6cd4375a05a07476444d5819985007e34"
+    },
+    {
+      "NIST P-256", 256, 1,
+      "0xffffffff00000001000000000000000000000000ffffffffffffffffffffffff",
+      "0xffffffff00000001000000000000000000000000fffffffffffffffffffffffc",
+      "0x5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b",
+      "0xffffffff00000000ffffffffffffffffbce6faada7179e84f3b9cac2fc632551",
+
+      "0x6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296",
+      "0x4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5"
+    },
+    {
+      "NIST P-384", 384, 1,
+      "0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe"
+      "ffffffff0000000000000000ffffffff",
+      "0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe"
+      "ffffffff0000000000000000fffffffc",
+      "0xb3312fa7e23ee7e4988e056be3f82d19181d9c6efe8141120314088f5013875a"
+      "c656398d8a2ed19d2a85c8edd3ec2aef",
+      "0xffffffffffffffffffffffffffffffffffffffffffffffffc7634d81f4372ddf"
+      "581a0db248b0a77aecec196accc52973",
+
+      "0xaa87ca22be8b05378eb1c71ef320ad746e1d3b628ba79b9859f741e082542a38"
+      "5502f25dbf55296c3a545e3872760ab7",
+      "0x3617de4a96262c6f5d9e98bf9292dc29f8f41dbd289a147ce9da3113b5f0b8c0"
+      "0a60b1ce1d7e819d7a431d7c90ea0e5f"
+    },
+    {
+      "NIST P-521", 521, 1,
+      "0x01ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"
+      "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
+      "0x01ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"
+      "fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffc",
+      "0x051953eb9618e1c9a1f929a21a0b68540eea2da725b99b315f3b8b489918ef10"
+      "9e156193951ec7e937b1652c0bd3bb1bf073573df883d2c34f1ef451fd46b503f00",
+      "0x1fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"
+      "ffa51868783bf2f966b7fcc0148f709a5d03bb5c9b8899c47aebb6fb71e91386409",
+
+      "0xc6858e06b70404e9cd9e3ecb662395b4429c648139053fb521f828af606b4d3d"
+      "baa14b5e77efe75928fe1dc127a2ffa8de3348b3c1856a429bf97e7e31c2e5bd66",
+      "0x11839296a789a3bc0045c8a5fb42c7d1bd998f54449579b446817afbd17273e6"
+      "62c97ee72995ef42640c550b9013fad0761353c7086a272c24088be94769fd16650"
+    },
+
+    { "brainpoolP160r1", 160, 0,
+      "0xe95e4a5f737059dc60dfc7ad95b3d8139515620f",
+      "0x340e7be2a280eb74e2be61bada745d97e8f7c300",
+      "0x1e589a8595423412134faa2dbdec95c8d8675e58",
+      "0xe95e4a5f737059dc60df5991d45029409e60fc09",
+      "0xbed5af16ea3f6a4f62938c4631eb5af7bdbcdbc3",
+      "0x1667cb477a1a8ec338f94741669c976316da6321"
+    },
+
+    { "brainpoolP192r1", 192, 0,
+      "0xc302f41d932a36cda7a3463093d18db78fce476de1a86297",
+      "0x6a91174076b1e0e19c39c031fe8685c1cae040e5c69a28ef",
+      "0x469a28ef7c28cca3dc721d044f4496bcca7ef4146fbf25c9",
+      "0xc302f41d932a36cda7a3462f9e9e916b5be8f1029ac4acc1",
+      "0xc0a0647eaab6a48753b033c56cb0f0900a2f5c4853375fd6",
+      "0x14b690866abd5bb88b5f4828c1490002e6773fa2fa299b8f"
+    },
+
+    { "brainpoolP224r1", 224, 0,
+      "0xd7c134aa264366862a18302575d1d787b09f075797da89f57ec8c0ff",
+      "0x68a5e62ca9ce6c1c299803a6c1530b514e182ad8b0042a59cad29f43",
+      "0x2580f63ccfe44138870713b1a92369e33e2135d266dbb372386c400b",
+      "0xd7c134aa264366862a18302575d0fb98d116bc4b6ddebca3a5a7939f",
+      "0x0d9029ad2c7e5cf4340823b2a87dc68c9e4ce3174c1e6efdee12c07d",
+      "0x58aa56f772c0726f24c6b89e4ecdac24354b9e99caa3f6d3761402cd"
+    },
+
+    { "brainpoolP256r1", 256, 0,
+      "0xa9fb57dba1eea9bc3e660a909d838d726e3bf623d52620282013481d1f6e5377",
+      "0x7d5a0975fc2c3057eef67530417affe7fb8055c126dc5c6ce94a4b44f330b5d9",
+      "0x26dc5c6ce94a4b44f330b5d9bbd77cbf958416295cf7e1ce6bccdc18ff8c07b6",
+      "0xa9fb57dba1eea9bc3e660a909d838d718c397aa3b561a6f7901e0e82974856a7",
+      "0x8bd2aeb9cb7e57cb2c4b482ffc81b7afb9de27e1e3bd23c23a4453bd9ace3262",
+      "0x547ef835c3dac4fd97f8461a14611dc9c27745132ded8e545c1d54c72f046997"
+    },
+
+    { "brainpoolP320r1", 320, 0,
+      "0xd35e472036bc4fb7e13c785ed201e065f98fcfa6f6f40def4f92b9ec7893ec28"
+      "fcd412b1f1b32e27",
+      "0x3ee30b568fbab0f883ccebd46d3f3bb8a2a73513f5eb79da66190eb085ffa9f4"
+      "92f375a97d860eb4",
+      "0x520883949dfdbc42d3ad198640688a6fe13f41349554b49acc31dccd88453981"
+      "6f5eb4ac8fb1f1a6",
+      "0xd35e472036bc4fb7e13c785ed201e065f98fcfa5b68f12a32d482ec7ee8658e9"
+      "8691555b44c59311",
+      "0x43bd7e9afb53d8b85289bcc48ee5bfe6f20137d10a087eb6e7871e2a10a599c7"
+      "10af8d0d39e20611",
+      "0x14fdd05545ec1cc8ab4093247f77275e0743ffed117182eaa9c77877aaac6ac7"
+      "d35245d1692e8ee1"
+    },
+
+    { "brainpoolP384r1", 384, 0,
+      "0x8cb91e82a3386d280f5d6f7e50e641df152f7109ed5456b412b1da197fb71123"
+      "acd3a729901d1a71874700133107ec53",
+      "0x7bc382c63d8c150c3c72080ace05afa0c2bea28e4fb22787139165efba91f90f"
+      "8aa5814a503ad4eb04a8c7dd22ce2826",
+      "0x04a8c7dd22ce28268b39b55416f0447c2fb77de107dcd2a62e880ea53eeb62d5"
+      "7cb4390295dbc9943ab78696fa504c11",
+      "0x8cb91e82a3386d280f5d6f7e50e641df152f7109ed5456b31f166e6cac0425a7"
+      "cf3ab6af6b7fc3103b883202e9046565",
+      "0x1d1c64f068cf45ffa2a63a81b7c13f6b8847a3e77ef14fe3db7fcafe0cbd10e8"
+      "e826e03436d646aaef87b2e247d4af1e",
+      "0x8abe1d7520f9c2a45cb1eb8e95cfd55262b70b29feec5864e19c054ff9912928"
+      "0e4646217791811142820341263c5315"
+    },
+
+    { "brainpoolP512r1", 512, 0,
+      "0xaadd9db8dbe9c48b3fd4e6ae33c9fc07cb308db3b3c9d20ed6639cca70330871"
+      "7d4d9b009bc66842aecda12ae6a380e62881ff2f2d82c68528aa6056583a48f3",
+      "0x7830a3318b603b89e2327145ac234cc594cbdd8d3df91610a83441caea9863bc"
+      "2ded5d5aa8253aa10a2ef1c98b9ac8b57f1117a72bf2c7b9e7c1ac4d77fc94ca",
+      "0x3df91610a83441caea9863bc2ded5d5aa8253aa10a2ef1c98b9ac8b57f1117a7"
+      "2bf2c7b9e7c1ac4d77fc94cadc083e67984050b75ebae5dd2809bd638016f723",
+      "0xaadd9db8dbe9c48b3fd4e6ae33c9fc07cb308db3b3c9d20ed6639cca70330870"
+      "553e5c414ca92619418661197fac10471db1d381085ddaddb58796829ca90069",
+      "0x81aee4bdd82ed9645a21322e9c4c6a9385ed9f70b5d916c1b43b62eef4d0098e"
+      "ff3b1f78e2d0d48d50d1687b93b97d5f7c6d5047406a5e688b352209bcb9f822",
+      "0x7dde385d566332ecc0eabfa9cf7822fdf209f70024a57b1aa000c55b881f8111"
+      "b2dcde494a5f485e5bca4bd88a2763aed1ca2b2fa8f0540678cd1e0f3ad80892"
+    },
+
+    { NULL, 0, 0, NULL, NULL, NULL, NULL }
+  };
+
+
+
+
+/* Helper to scan a hex string. */
+static gcry_mpi_t
+scanval (const char *string)
+{
+  gpg_error_t err;
+  gcry_mpi_t val;
+
+  err = gcry_mpi_scan (&val, GCRYMPI_FMT_HEX, string, 0, NULL);
+  if (err)
+    log_fatal ("scanning ECC parameter failed: %s\n", gpg_strerror (err));
+  return val;
+}
+
+
+/* Generate the crypto system setup.  This function takes the NAME of
+   a curve or the desired number of bits and stores at R_CURVE the
+   parameters of the named curve or those of a suitable curve.  If
+   R_NBITS is not NULL, the chosen number of bits is stored there.  */
+gpg_err_code_t
+_gcry_ecc_fill_in_curve (unsigned int nbits, const char *name,
+                         elliptic_curve_t *curve, unsigned int *r_nbits)
+{
+  int idx, aliasno;
+  const char *resname = NULL; /* Set to a found curve name.  */
+
+  if (name)
+    {
+      /* First check our native curves.  */
+      for (idx = 0; domain_parms[idx].desc; idx++)
+        if (!strcmp (name, domain_parms[idx].desc))
+          {
+            resname = domain_parms[idx].desc;
+            break;
+          }
+      /* If not found consult the alias table.  */
+      if (!domain_parms[idx].desc)
+        {
+          for (aliasno = 0; curve_aliases[aliasno].name; aliasno++)
+            if (!strcmp (name, curve_aliases[aliasno].other))
+              break;
+          if (curve_aliases[aliasno].name)
+            {
+              for (idx = 0; domain_parms[idx].desc; idx++)
+                if (!strcmp (curve_aliases[aliasno].name,
+                             domain_parms[idx].desc))
+                  {
+                    resname = domain_parms[idx].desc;
+                    break;
+                  }
+            }
+        }
+    }
+  else
+    {
+      for (idx = 0; domain_parms[idx].desc; idx++)
+        if (nbits == domain_parms[idx].nbits)
+          break;
+    }
+  if (!domain_parms[idx].desc)
+    return GPG_ERR_INV_VALUE;
+
+  /* In fips mode we only support NIST curves.  Note that it is
+     possible to bypass this check by specifying the curve parameters
+     directly.  */
+  if (fips_mode () && !domain_parms[idx].fips )
+    return GPG_ERR_NOT_SUPPORTED;
+
+  if (r_nbits)
+    *r_nbits = domain_parms[idx].nbits;
+  curve->p = scanval (domain_parms[idx].p);
+  curve->a = scanval (domain_parms[idx].a);
+  curve->b = scanval (domain_parms[idx].b);
+  curve->n = scanval (domain_parms[idx].n);
+  curve->G.x = scanval (domain_parms[idx].g_x);
+  curve->G.y = scanval (domain_parms[idx].g_y);
+  curve->G.z = mpi_alloc_set_ui (1);
+  curve->name = resname;
+
+  return 0;
+}
+
+
+/* Return the name matching the parameters in PKEY.  */
+const char *
+_gcry_ecc_get_curve (gcry_mpi_t *pkey, int iterator, unsigned int *r_nbits)
+{
+  gpg_err_code_t err;
+  elliptic_curve_t E;
+  int idx;
+  gcry_mpi_t tmp;
+  const char *result = NULL;
+
+  if (r_nbits)
+    *r_nbits = 0;
+
+  if (!pkey)
+    {
+      idx = iterator;
+      if (idx >= 0 && idx < DIM (domain_parms))
+        {
+          result = domain_parms[idx].desc;
+          if (r_nbits)
+            *r_nbits = domain_parms[idx].nbits;
+        }
+      return result;
+    }
+
+  if (!pkey[0] || !pkey[1] || !pkey[2] || !pkey[3] || !pkey[4])
+    return NULL;
+
+  E.p = pkey[0];
+  E.a = pkey[1];
+  E.b = pkey[2];
+  _gcry_mpi_point_init (&E.G);
+  err = _gcry_ecc_os2ec (&E.G, pkey[3]);
+  if (err)
+    {
+      _gcry_mpi_point_free_parts (&E.G);
+      return NULL;
+    }
+  E.n = pkey[4];
+
+  for (idx = 0; domain_parms[idx].desc; idx++)
+    {
+      tmp = scanval (domain_parms[idx].p);
+      if (!mpi_cmp (tmp, E.p))
+        {
+          mpi_free (tmp);
+          tmp = scanval (domain_parms[idx].a);
+          if (!mpi_cmp (tmp, E.a))
+            {
+              mpi_free (tmp);
+              tmp = scanval (domain_parms[idx].b);
+              if (!mpi_cmp (tmp, E.b))
+                {
+                  mpi_free (tmp);
+                  tmp = scanval (domain_parms[idx].n);
+                  if (!mpi_cmp (tmp, E.n))
+                    {
+                      mpi_free (tmp);
+                      tmp = scanval (domain_parms[idx].g_x);
+                      if (!mpi_cmp (tmp, E.G.x))
+                        {
+                          mpi_free (tmp);
+                          tmp = scanval (domain_parms[idx].g_y);
+                          if (!mpi_cmp (tmp, E.G.y))
+                            {
+                              mpi_free (tmp);
+                              result = domain_parms[idx].desc;
+                              if (r_nbits)
+                                *r_nbits = domain_parms[idx].nbits;
+                              break;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+      mpi_free (tmp);
+    }
+
+  _gcry_mpi_point_free_parts (&E.G);
+
+  return result;
+}
+
+
+/* Helper to extract an MPI from key parameters.  */
+static gpg_err_code_t
+mpi_from_keyparam (gcry_mpi_t *r_a, gcry_sexp_t keyparam, const char *name)
+{
+  gcry_err_code_t ec = 0;
+  gcry_sexp_t l1;
+
+  l1 = gcry_sexp_find_token (keyparam, name, 0);
+  if (l1)
+    {
+      *r_a = gcry_sexp_nth_mpi (l1, 1, GCRYMPI_FMT_USG);
+      gcry_sexp_release (l1);
+      if (!*r_a)
+        ec = GPG_ERR_INV_OBJ;
+    }
+  return ec;
+}
+
+/* Helper to extract a point from key parameters.  If no parameter
+   with NAME is found, the functions tries to find a non-encoded point
+   by appending ".x", ".y" and ".z" to NAME.  ".z" is in this case
+   optional and defaults to 1.  */
+static gpg_err_code_t
+point_from_keyparam (gcry_mpi_point_t *r_a,
+                     gcry_sexp_t keyparam, const char *name)
+{
+  gcry_err_code_t ec;
+  gcry_mpi_t a = NULL;
+  gcry_mpi_point_t point;
+
+  ec = mpi_from_keyparam (&a, keyparam, name);
+  if (ec)
+    return ec;
+
+  if (a)
+    {
+      point = gcry_mpi_point_new (0);
+      ec = _gcry_ecc_os2ec (point, a);
+      mpi_free (a);
+      if (ec)
+        {
+          gcry_mpi_point_release (point);
+          return ec;
+        }
+    }
+  else
+    {
+      char *tmpname;
+      gcry_mpi_t x = NULL;
+      gcry_mpi_t y = NULL;
+      gcry_mpi_t z = NULL;
+
+      tmpname = gcry_malloc (strlen (name) + 2 + 1);
+      if (!tmpname)
+        return gpg_err_code_from_syserror ();
+      strcpy (stpcpy (tmpname, name), ".x");
+      ec = mpi_from_keyparam (&x, keyparam, tmpname);
+      if (ec)
+        {
+          gcry_free (tmpname);
+          return ec;
+        }
+      strcpy (stpcpy (tmpname, name), ".y");
+      ec = mpi_from_keyparam (&y, keyparam, tmpname);
+      if (ec)
+        {
+          mpi_free (x);
+          gcry_free (tmpname);
+          return ec;
+        }
+      strcpy (stpcpy (tmpname, name), ".z");
+      ec = mpi_from_keyparam (&z, keyparam, tmpname);
+      if (ec)
+        {
+          mpi_free (y);
+          mpi_free (x);
+          gcry_free (tmpname);
+          return ec;
+        }
+      if (!z)
+        z = mpi_set_ui (NULL, 1);
+      if (x && y)
+        point = gcry_mpi_point_snatch_set (NULL, x, y, z);
+      else
+        {
+          mpi_free (x);
+          mpi_free (y);
+          mpi_free (z);
+          point = NULL;
+        }
+      gcry_free (tmpname);
+    }
+
+  if (point)
+    *r_a = point;
+  return 0;
+}
+
+
+/* This function creates a new context for elliptic curve operations.
+   Either KEYPARAM or CURVENAME must be given.  If both are given and
+   KEYPARAM has no curve parameter CURVENAME is used to add missing
+   parameters.  On success 0 is returned and the new context stored at
+   R_CTX.  On error NULL is stored at R_CTX and an error code is
+   returned.  The context needs to be released using
+   gcry_ctx_release.  */
+gpg_err_code_t
+_gcry_mpi_ec_new (gcry_ctx_t *r_ctx,
+                  gcry_sexp_t keyparam, const char *curvename)
+{
+  gpg_err_code_t errc;
+  gcry_ctx_t ctx = NULL;
+  gcry_mpi_t p = NULL;
+  gcry_mpi_t a = NULL;
+  gcry_mpi_t b = NULL;
+  gcry_mpi_point_t G = NULL;
+  gcry_mpi_t n = NULL;
+  gcry_mpi_point_t Q = NULL;
+  gcry_mpi_t d = NULL;
+  gcry_sexp_t l1;
+
+  *r_ctx = NULL;
+
+  if (keyparam)
+    {
+      errc = mpi_from_keyparam (&p, keyparam, "p");
+      if (errc)
+        goto leave;
+      errc = mpi_from_keyparam (&a, keyparam, "a");
+      if (errc)
+        goto leave;
+      errc = mpi_from_keyparam (&b, keyparam, "b");
+      if (errc)
+        goto leave;
+      errc = point_from_keyparam (&G, keyparam, "g");
+      if (errc)
+        goto leave;
+      errc = mpi_from_keyparam (&n, keyparam, "n");
+      if (errc)
+        goto leave;
+      errc = point_from_keyparam (&Q, keyparam, "q");
+      if (errc)
+        goto leave;
+      errc = mpi_from_keyparam (&d, keyparam, "d");
+      if (errc)
+        goto leave;
+    }
+
+
+  /* Check whether a curve parameter is available and use that to fill
+     in missing values.  If no curve parameter is available try an
+     optional provided curvename.  If only the curvename has been
+     given use that one. */
+  if (keyparam)
+    l1 = gcry_sexp_find_token (keyparam, "curve", 5);
+  else
+    l1 = NULL;
+  if (l1 || curvename)
+    {
+      char *name;
+      elliptic_curve_t *E;
+
+      if (l1)
+        {
+          name = _gcry_sexp_nth_string (l1, 1);
+          gcry_sexp_release (l1);
+          if (!name)
+            {
+              errc = GPG_ERR_INV_OBJ; /* Name missing or out of core. */
+              goto leave;
+            }
+        }
+      else
+        name = NULL;
+
+      E = gcry_calloc (1, sizeof *E);
+      if (!E)
+        {
+          errc = gpg_err_code_from_syserror ();
+          gcry_free (name);
+          goto leave;
+        }
+
+      errc = _gcry_ecc_fill_in_curve (0, name? name : curvename, E, NULL);
+      gcry_free (name);
+      if (errc)
+        {
+          gcry_free (E);
+          goto leave;
+        }
+
+      if (!p)
+        {
+          p = E->p;
+          E->p = NULL;
+        }
+      if (!a)
+        {
+          a = E->a;
+          E->a = NULL;
+        }
+      if (!b)
+        {
+          b = E->b;
+          E->b = NULL;
+        }
+      if (!G)
+        {
+          G = gcry_mpi_point_snatch_set (NULL, E->G.x, E->G.y, E->G.z);
+          E->G.x = NULL;
+          E->G.y = NULL;
+          E->G.z = NULL;
+        }
+      if (!n)
+        {
+          n = E->n;
+          E->n = NULL;
+        }
+      _gcry_ecc_curve_free (E);
+      gcry_free (E);
+    }
+
+  errc = _gcry_mpi_ec_p_new (&ctx, p, a);
+  if (!errc)
+    {
+      mpi_ec_t ec = _gcry_ctx_get_pointer (ctx, CONTEXT_TYPE_EC);
+
+      if (b)
+        {
+          ec->b = b;
+          b = NULL;
+        }
+      if (G)
+        {
+          ec->G = G;
+          G = NULL;
+        }
+      if (n)
+        {
+          ec->n = n;
+          n = NULL;
+        }
+      if (Q)
+        {
+          ec->Q = Q;
+          Q = NULL;
+        }
+      if (d)
+        {
+          ec->d = d;
+          d = NULL;
+        }
+
+      *r_ctx = ctx;
+    }
+
+ leave:
+  mpi_free (p);
+  mpi_free (a);
+  mpi_free (b);
+  gcry_mpi_point_release (G);
+  mpi_free (n);
+  gcry_mpi_point_release (Q);
+  mpi_free (d);
+  return errc;
+}
+
+
+/* Return the parameters of the curve NAME in an MPI array.  */
+gcry_err_code_t
+_gcry_ecc_get_param (const char *name, gcry_mpi_t *pkey)
+{
+  gpg_err_code_t err;
+  unsigned int nbits;
+  elliptic_curve_t E;
+  mpi_ec_t ctx;
+  gcry_mpi_t g_x, g_y;
+
+  err = _gcry_ecc_fill_in_curve (0, name, &E, &nbits);
+  if (err)
+    return err;
+
+  g_x = mpi_new (0);
+  g_y = mpi_new (0);
+  ctx = _gcry_mpi_ec_p_internal_new (E.p, E.a);
+  if (_gcry_mpi_ec_get_affine (g_x, g_y, &E.G, ctx))
+    log_fatal ("ecc get param: Failed to get affine coordinates\n");
+  _gcry_mpi_ec_free (ctx);
+  _gcry_mpi_point_free_parts (&E.G);
+
+  pkey[0] = E.p;
+  pkey[1] = E.a;
+  pkey[2] = E.b;
+  pkey[3] = _gcry_ecc_ec2os (g_x, g_y, E.p);
+  pkey[4] = E.n;
+  pkey[5] = NULL;
+
+  mpi_free (g_x);
+  mpi_free (g_y);
+
+  return 0;
+}
+
+
+/* Return the parameters of the curve NAME as an S-expression.  */
+gcry_sexp_t
+_gcry_ecc_get_param_sexp (const char *name)
+{
+  gcry_mpi_t pkey[6];
+  gcry_sexp_t result;
+  int i;
+
+  if (_gcry_ecc_get_param (name, pkey))
+    return NULL;
+
+  if (gcry_sexp_build (&result, NULL,
+                       "(public-key(ecc(p%m)(a%m)(b%m)(g%m)(n%m)))",
+                       pkey[0], pkey[1], pkey[2], pkey[3], pkey[4]))
+    result = NULL;
+
+  for (i=0; pkey[i]; i++)
+    gcry_mpi_release (pkey[i]);
+
+  return result;
+}