From 164eb8c85d773ef4f0939115ec45f5e4b47c1700 Mon Sep 17 00:00:00 2001 From: Werner Koch Date: Wed, 23 Oct 2013 14:08:29 +0200 Subject: ecc: Refactor ecc.c * cipher/ecc-ecdsa.c, cipher/ecc-eddsa.c, cipher/ecc-gost.c: New. * cipher/Makefile.am (EXTRA_libcipher_la_SOURCES): Add new files. * configure.ac (GCRYPT_PUBKEY_CIPHERS): Add new files. * cipher/ecc.c (point_init, point_free): Move to ecc-common.h. (sign_ecdsa): Move to ecc-ecdsa.c as _gcry_ecc_ecdsa_sign. (verify_ecdsa): Move to ecc-ecdsa.c as _gcry_ecc_ecdsa_verify. (sign_gost): Move to ecc-gots.c as _gcry_ecc_gost_sign. (verify_gost): Move to ecc-gost.c as _gcry_ecc_gost_verify. (sign_eddsa): Move to ecc-eddsa.c as _gcry_ecc_eddsa_sign. (verify_eddsa): Move to ecc-eddsa.c as _gcry_ecc_eddsa_verify. (eddsa_generate_key): Move to ecc-eddsa.c as _gcry_ecc_eddsa_genkey. (reverse_buffer): Move to ecc-eddsa.c. (eddsa_encodempi, eddsa_encode_x_y): Ditto. (_gcry_ecc_eddsa_encodepoint, _gcry_ecc_eddsa_decodepoint): Ditto. -- This change should make it easier to add new ECC algorithms. Signed-off-by: Werner Koch --- cipher/ecc-gost.c | 233 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 233 insertions(+) create mode 100644 cipher/ecc-gost.c (limited to 'cipher/ecc-gost.c') diff --git a/cipher/ecc-gost.c b/cipher/ecc-gost.c new file mode 100644 index 00000000..1ebfd392 --- /dev/null +++ b/cipher/ecc-gost.c @@ -0,0 +1,233 @@ +/* ecc-gots.c - Elliptic Curve GOST signatures + * Copyright (C) 2007, 2008, 2010, 2011 Free Software Foundation, Inc. + * Copyright (C) 2013 Dmitry Eremin-Solenikov + * + * 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 . + */ + +#include +#include +#include +#include +#include + +#include "g10lib.h" +#include "mpi.h" +#include "cipher.h" +#include "context.h" +#include "ec-context.h" +#include "ecc-common.h" + + +/* Compute an GOST R 34.10-01/-12 signature. + * Return the signature struct (r,s) from the message hash. The caller + * must have allocated R and S. + */ +gpg_err_code_t +_gcry_ecc_gost_sign (gcry_mpi_t input, ECC_secret_key *skey, + gcry_mpi_t r, gcry_mpi_t s) +{ + gpg_err_code_t err = 0; + gcry_mpi_t k, dr, sum, ke, x, e; + mpi_point_struct I; + gcry_mpi_t hash; + const void *abuf; + unsigned int abits, qbits; + mpi_ec_t ctx; + + if (DBG_CIPHER) + log_mpidump ("gost sign hash ", input ); + + qbits = mpi_get_nbits (skey->E.n); + + /* Convert the INPUT into an MPI if needed. */ + if (mpi_is_opaque (input)) + { + abuf = gcry_mpi_get_opaque (input, &abits); + err = gpg_err_code (gcry_mpi_scan (&hash, GCRYMPI_FMT_USG, + abuf, (abits+7)/8, NULL)); + if (err) + return err; + if (abits > qbits) + gcry_mpi_rshift (hash, hash, abits - qbits); + } + else + hash = input; + + + k = NULL; + dr = mpi_alloc (0); + sum = mpi_alloc (0); + ke = mpi_alloc (0); + e = mpi_alloc (0); + x = mpi_alloc (0); + point_init (&I); + + ctx = _gcry_mpi_ec_p_internal_new (skey->E.model, skey->E.dialect, + skey->E.p, skey->E.a, skey->E.b); + + mpi_mod (e, input, skey->E.n); /* e = hash mod n */ + + if (!mpi_cmp_ui (e, 0)) + mpi_set_ui (e, 1); + + /* Two loops to avoid R or S are zero. This is more of a joke than + a real demand because the probability of them being zero is less + than any hardware failure. Some specs however require it. */ + do + { + do + { + mpi_free (k); + k = _gcry_dsa_gen_k (skey->E.n, GCRY_STRONG_RANDOM); + + _gcry_mpi_ec_mul_point (&I, k, &skey->E.G, ctx); + if (_gcry_mpi_ec_get_affine (x, NULL, &I, ctx)) + { + if (DBG_CIPHER) + log_debug ("ecc sign: Failed to get affine coordinates\n"); + err = GPG_ERR_BAD_SIGNATURE; + goto leave; + } + mpi_mod (r, x, skey->E.n); /* r = x mod n */ + } + while (!mpi_cmp_ui (r, 0)); + mpi_mulm (dr, skey->d, r, skey->E.n); /* dr = d*r mod n */ + mpi_mulm (ke, k, e, skey->E.n); /* ke = k*e mod n */ + mpi_addm (s, ke, dr, skey->E.n); /* sum = (k*e+ d*r) mod n */ + } + while (!mpi_cmp_ui (s, 0)); + + if (DBG_CIPHER) + { + log_mpidump ("gost sign result r ", r); + log_mpidump ("gost sign result s ", s); + } + + leave: + _gcry_mpi_ec_free (ctx); + point_free (&I); + mpi_free (x); + mpi_free (e); + mpi_free (ke); + mpi_free (sum); + mpi_free (dr); + mpi_free (k); + + if (hash != input) + mpi_free (hash); + + return err; +} + + +/* Verify a GOST R 34.10-01/-12 signature. + * Check if R and S verifies INPUT. + */ +gpg_err_code_t +_gcry_ecc_gost_verify (gcry_mpi_t input, ECC_public_key *pkey, + gcry_mpi_t r, gcry_mpi_t s) +{ + gpg_err_code_t err = 0; + gcry_mpi_t e, x, z1, z2, v, rv, zero; + mpi_point_struct Q, Q1, Q2; + mpi_ec_t ctx; + + if( !(mpi_cmp_ui (r, 0) > 0 && mpi_cmp (r, pkey->E.n) < 0) ) + return GPG_ERR_BAD_SIGNATURE; /* Assertion 0 < r < n failed. */ + if( !(mpi_cmp_ui (s, 0) > 0 && mpi_cmp (s, pkey->E.n) < 0) ) + return GPG_ERR_BAD_SIGNATURE; /* Assertion 0 < s < n failed. */ + + x = mpi_alloc (0); + e = mpi_alloc (0); + z1 = mpi_alloc (0); + z2 = mpi_alloc (0); + v = mpi_alloc (0); + rv = mpi_alloc (0); + zero = mpi_alloc (0); + + point_init (&Q); + point_init (&Q1); + point_init (&Q2); + + ctx = _gcry_mpi_ec_p_internal_new (pkey->E.model, pkey->E.dialect, + pkey->E.p, pkey->E.a, pkey->E.b); + + mpi_mod (e, input, pkey->E.n); /* e = hash mod n */ + if (!mpi_cmp_ui (e, 0)) + mpi_set_ui (e, 1); + mpi_invm (v, e, pkey->E.n); /* v = e^(-1) (mod n) */ + mpi_mulm (z1, s, v, pkey->E.n); /* z1 = s*v (mod n) */ + mpi_mulm (rv, r, v, pkey->E.n); /* rv = s*v (mod n) */ + mpi_subm (z2, zero, rv, pkey->E.n); /* z2 = -r*v (mod n) */ + + _gcry_mpi_ec_mul_point (&Q1, z1, &pkey->E.G, ctx); +/* log_mpidump ("Q1.x", Q1.x); */ +/* log_mpidump ("Q1.y", Q1.y); */ +/* log_mpidump ("Q1.z", Q1.z); */ + _gcry_mpi_ec_mul_point (&Q2, z2, &pkey->Q, ctx); +/* log_mpidump ("Q2.x", Q2.x); */ +/* log_mpidump ("Q2.y", Q2.y); */ +/* log_mpidump ("Q2.z", Q2.z); */ + _gcry_mpi_ec_add_points (&Q, &Q1, &Q2, ctx); +/* log_mpidump (" Q.x", Q.x); */ +/* log_mpidump (" Q.y", Q.y); */ +/* log_mpidump (" Q.z", Q.z); */ + + if (!mpi_cmp_ui (Q.z, 0)) + { + if (DBG_CIPHER) + log_debug ("ecc verify: Rejected\n"); + err = GPG_ERR_BAD_SIGNATURE; + goto leave; + } + if (_gcry_mpi_ec_get_affine (x, NULL, &Q, ctx)) + { + if (DBG_CIPHER) + log_debug ("ecc verify: Failed to get affine coordinates\n"); + err = GPG_ERR_BAD_SIGNATURE; + goto leave; + } + mpi_mod (x, x, pkey->E.n); /* x = x mod E_n */ + if (mpi_cmp (x, r)) /* x != r */ + { + if (DBG_CIPHER) + { + log_mpidump (" x", x); + log_mpidump (" r", r); + log_mpidump (" s", s); + log_debug ("ecc verify: Not verified\n"); + } + err = GPG_ERR_BAD_SIGNATURE; + goto leave; + } + if (DBG_CIPHER) + log_debug ("ecc verify: Accepted\n"); + + leave: + _gcry_mpi_ec_free (ctx); + point_free (&Q2); + point_free (&Q1); + point_free (&Q); + mpi_free (zero); + mpi_free (rv); + mpi_free (v); + mpi_free (z2); + mpi_free (z1); + mpi_free (x); + mpi_free (e); + return err; +} -- cgit v1.2.1