EL4121 Embedded System / mbed-os

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features/mbedtls/src/ecdsa.c@0:b74591d5ab33, 2017-12-11 (annotated)

Committer:
be_bryan
Date:
Mon Dec 11 17:54:04 2017 +0000
Revision:
0:b74591d5ab33
motor ++

Who changed what in which revision?

UserRevisionLine numberNew contents of line
be_bryan 0:b74591d5ab33 1 /*
be_bryan 0:b74591d5ab33 2 * Elliptic curve DSA
be_bryan 0:b74591d5ab33 3 *
be_bryan 0:b74591d5ab33 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
be_bryan 0:b74591d5ab33 5 * SPDX-License-Identifier: Apache-2.0
be_bryan 0:b74591d5ab33 6 *
be_bryan 0:b74591d5ab33 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
be_bryan 0:b74591d5ab33 8 * not use this file except in compliance with the License.
be_bryan 0:b74591d5ab33 9 * You may obtain a copy of the License at
be_bryan 0:b74591d5ab33 10 *
be_bryan 0:b74591d5ab33 11 * http://www.apache.org/licenses/LICENSE-2.0
be_bryan 0:b74591d5ab33 12 *
be_bryan 0:b74591d5ab33 13 * Unless required by applicable law or agreed to in writing, software
be_bryan 0:b74591d5ab33 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
be_bryan 0:b74591d5ab33 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
be_bryan 0:b74591d5ab33 16 * See the License for the specific language governing permissions and
be_bryan 0:b74591d5ab33 17 * limitations under the License.
be_bryan 0:b74591d5ab33 18 *
be_bryan 0:b74591d5ab33 19 * This file is part of mbed TLS (https://tls.mbed.org)
be_bryan 0:b74591d5ab33 20 */
be_bryan 0:b74591d5ab33 21
be_bryan 0:b74591d5ab33 22 /*
be_bryan 0:b74591d5ab33 23 * References:
be_bryan 0:b74591d5ab33 24 *
be_bryan 0:b74591d5ab33 25 * SEC1 http://www.secg.org/index.php?action=secg,docs_secg
be_bryan 0:b74591d5ab33 26 */
be_bryan 0:b74591d5ab33 27
be_bryan 0:b74591d5ab33 28 #if !defined(MBEDTLS_CONFIG_FILE)
be_bryan 0:b74591d5ab33 29 #include "mbedtls/config.h"
be_bryan 0:b74591d5ab33 30 #else
be_bryan 0:b74591d5ab33 31 #include MBEDTLS_CONFIG_FILE
be_bryan 0:b74591d5ab33 32 #endif
be_bryan 0:b74591d5ab33 33
be_bryan 0:b74591d5ab33 34 #if defined(MBEDTLS_ECDSA_C)
be_bryan 0:b74591d5ab33 35
be_bryan 0:b74591d5ab33 36 #include "mbedtls/ecdsa.h"
be_bryan 0:b74591d5ab33 37 #include "mbedtls/asn1write.h"
be_bryan 0:b74591d5ab33 38
be_bryan 0:b74591d5ab33 39 #include <string.h>
be_bryan 0:b74591d5ab33 40
be_bryan 0:b74591d5ab33 41 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
be_bryan 0:b74591d5ab33 42 #include "mbedtls/hmac_drbg.h"
be_bryan 0:b74591d5ab33 43 #endif
be_bryan 0:b74591d5ab33 44
be_bryan 0:b74591d5ab33 45 /*
be_bryan 0:b74591d5ab33 46 * Derive a suitable integer for group grp from a buffer of length len
be_bryan 0:b74591d5ab33 47 * SEC1 4.1.3 step 5 aka SEC1 4.1.4 step 3
be_bryan 0:b74591d5ab33 48 */
be_bryan 0:b74591d5ab33 49 static int derive_mpi( const mbedtls_ecp_group *grp, mbedtls_mpi *x,
be_bryan 0:b74591d5ab33 50 const unsigned char *buf, size_t blen )
be_bryan 0:b74591d5ab33 51 {
be_bryan 0:b74591d5ab33 52 int ret;
be_bryan 0:b74591d5ab33 53 size_t n_size = ( grp->nbits + 7 ) / 8;
be_bryan 0:b74591d5ab33 54 size_t use_size = blen > n_size ? n_size : blen;
be_bryan 0:b74591d5ab33 55
be_bryan 0:b74591d5ab33 56 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( x, buf, use_size ) );
be_bryan 0:b74591d5ab33 57 if( use_size * 8 > grp->nbits )
be_bryan 0:b74591d5ab33 58 MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( x, use_size * 8 - grp->nbits ) );
be_bryan 0:b74591d5ab33 59
be_bryan 0:b74591d5ab33 60 /* While at it, reduce modulo N */
be_bryan 0:b74591d5ab33 61 if( mbedtls_mpi_cmp_mpi( x, &grp->N ) >= 0 )
be_bryan 0:b74591d5ab33 62 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( x, x, &grp->N ) );
be_bryan 0:b74591d5ab33 63
be_bryan 0:b74591d5ab33 64 cleanup:
be_bryan 0:b74591d5ab33 65 return( ret );
be_bryan 0:b74591d5ab33 66 }
be_bryan 0:b74591d5ab33 67
be_bryan 0:b74591d5ab33 68 /*
be_bryan 0:b74591d5ab33 69 * Compute ECDSA signature of a hashed message (SEC1 4.1.3)
be_bryan 0:b74591d5ab33 70 * Obviously, compared to SEC1 4.1.3, we skip step 4 (hash message)
be_bryan 0:b74591d5ab33 71 */
be_bryan 0:b74591d5ab33 72 int mbedtls_ecdsa_sign( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
be_bryan 0:b74591d5ab33 73 const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
be_bryan 0:b74591d5ab33 74 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
be_bryan 0:b74591d5ab33 75 {
be_bryan 0:b74591d5ab33 76 int ret, key_tries, sign_tries, blind_tries;
be_bryan 0:b74591d5ab33 77 mbedtls_ecp_point R;
be_bryan 0:b74591d5ab33 78 mbedtls_mpi k, e, t;
be_bryan 0:b74591d5ab33 79
be_bryan 0:b74591d5ab33 80 /* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */
be_bryan 0:b74591d5ab33 81 if( grp->N.p == NULL )
be_bryan 0:b74591d5ab33 82 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
be_bryan 0:b74591d5ab33 83
be_bryan 0:b74591d5ab33 84 mbedtls_ecp_point_init( &R );
be_bryan 0:b74591d5ab33 85 mbedtls_mpi_init( &k ); mbedtls_mpi_init( &e ); mbedtls_mpi_init( &t );
be_bryan 0:b74591d5ab33 86
be_bryan 0:b74591d5ab33 87 sign_tries = 0;
be_bryan 0:b74591d5ab33 88 do
be_bryan 0:b74591d5ab33 89 {
be_bryan 0:b74591d5ab33 90 /*
be_bryan 0:b74591d5ab33 91 * Steps 1-3: generate a suitable ephemeral keypair
be_bryan 0:b74591d5ab33 92 * and set r = xR mod n
be_bryan 0:b74591d5ab33 93 */
be_bryan 0:b74591d5ab33 94 key_tries = 0;
be_bryan 0:b74591d5ab33 95 do
be_bryan 0:b74591d5ab33 96 {
be_bryan 0:b74591d5ab33 97 MBEDTLS_MPI_CHK( mbedtls_ecp_gen_keypair( grp, &k, &R, f_rng, p_rng ) );
be_bryan 0:b74591d5ab33 98 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( r, &R.X, &grp->N ) );
be_bryan 0:b74591d5ab33 99
be_bryan 0:b74591d5ab33 100 if( key_tries++ > 10 )
be_bryan 0:b74591d5ab33 101 {
be_bryan 0:b74591d5ab33 102 ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
be_bryan 0:b74591d5ab33 103 goto cleanup;
be_bryan 0:b74591d5ab33 104 }
be_bryan 0:b74591d5ab33 105 }
be_bryan 0:b74591d5ab33 106 while( mbedtls_mpi_cmp_int( r, 0 ) == 0 );
be_bryan 0:b74591d5ab33 107
be_bryan 0:b74591d5ab33 108 /*
be_bryan 0:b74591d5ab33 109 * Step 5: derive MPI from hashed message
be_bryan 0:b74591d5ab33 110 */
be_bryan 0:b74591d5ab33 111 MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) );
be_bryan 0:b74591d5ab33 112
be_bryan 0:b74591d5ab33 113 /*
be_bryan 0:b74591d5ab33 114 * Generate a random value to blind inv_mod in next step,
be_bryan 0:b74591d5ab33 115 * avoiding a potential timing leak.
be_bryan 0:b74591d5ab33 116 */
be_bryan 0:b74591d5ab33 117 blind_tries = 0;
be_bryan 0:b74591d5ab33 118 do
be_bryan 0:b74591d5ab33 119 {
be_bryan 0:b74591d5ab33 120 size_t n_size = ( grp->nbits + 7 ) / 8;
be_bryan 0:b74591d5ab33 121 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &t, n_size, f_rng, p_rng ) );
be_bryan 0:b74591d5ab33 122 MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &t, 8 * n_size - grp->nbits ) );
be_bryan 0:b74591d5ab33 123
be_bryan 0:b74591d5ab33 124 /* See mbedtls_ecp_gen_keypair() */
be_bryan 0:b74591d5ab33 125 if( ++blind_tries > 30 )
be_bryan 0:b74591d5ab33 126 return( MBEDTLS_ERR_ECP_RANDOM_FAILED );
be_bryan 0:b74591d5ab33 127 }
be_bryan 0:b74591d5ab33 128 while( mbedtls_mpi_cmp_int( &t, 1 ) < 0 ||
be_bryan 0:b74591d5ab33 129 mbedtls_mpi_cmp_mpi( &t, &grp->N ) >= 0 );
be_bryan 0:b74591d5ab33 130
be_bryan 0:b74591d5ab33 131 /*
be_bryan 0:b74591d5ab33 132 * Step 6: compute s = (e + r * d) / k = t (e + rd) / (kt) mod n
be_bryan 0:b74591d5ab33 133 */
be_bryan 0:b74591d5ab33 134 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, r, d ) );
be_bryan 0:b74591d5ab33 135 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &e, &e, s ) );
be_bryan 0:b74591d5ab33 136 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &e, &e, &t ) );
be_bryan 0:b74591d5ab33 137 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &k, &k, &t ) );
be_bryan 0:b74591d5ab33 138 MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( s, &k, &grp->N ) );
be_bryan 0:b74591d5ab33 139 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, s, &e ) );
be_bryan 0:b74591d5ab33 140 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( s, s, &grp->N ) );
be_bryan 0:b74591d5ab33 141
be_bryan 0:b74591d5ab33 142 if( sign_tries++ > 10 )
be_bryan 0:b74591d5ab33 143 {
be_bryan 0:b74591d5ab33 144 ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
be_bryan 0:b74591d5ab33 145 goto cleanup;
be_bryan 0:b74591d5ab33 146 }
be_bryan 0:b74591d5ab33 147 }
be_bryan 0:b74591d5ab33 148 while( mbedtls_mpi_cmp_int( s, 0 ) == 0 );
be_bryan 0:b74591d5ab33 149
be_bryan 0:b74591d5ab33 150 cleanup:
be_bryan 0:b74591d5ab33 151 mbedtls_ecp_point_free( &R );
be_bryan 0:b74591d5ab33 152 mbedtls_mpi_free( &k ); mbedtls_mpi_free( &e ); mbedtls_mpi_free( &t );
be_bryan 0:b74591d5ab33 153
be_bryan 0:b74591d5ab33 154 return( ret );
be_bryan 0:b74591d5ab33 155 }
be_bryan 0:b74591d5ab33 156
be_bryan 0:b74591d5ab33 157 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
be_bryan 0:b74591d5ab33 158 /*
be_bryan 0:b74591d5ab33 159 * Deterministic signature wrapper
be_bryan 0:b74591d5ab33 160 */
be_bryan 0:b74591d5ab33 161 int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
be_bryan 0:b74591d5ab33 162 const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
be_bryan 0:b74591d5ab33 163 mbedtls_md_type_t md_alg )
be_bryan 0:b74591d5ab33 164 {
be_bryan 0:b74591d5ab33 165 int ret;
be_bryan 0:b74591d5ab33 166 mbedtls_hmac_drbg_context rng_ctx;
be_bryan 0:b74591d5ab33 167 unsigned char data[2 * MBEDTLS_ECP_MAX_BYTES];
be_bryan 0:b74591d5ab33 168 size_t grp_len = ( grp->nbits + 7 ) / 8;
be_bryan 0:b74591d5ab33 169 const mbedtls_md_info_t *md_info;
be_bryan 0:b74591d5ab33 170 mbedtls_mpi h;
be_bryan 0:b74591d5ab33 171
be_bryan 0:b74591d5ab33 172 if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) == NULL )
be_bryan 0:b74591d5ab33 173 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
be_bryan 0:b74591d5ab33 174
be_bryan 0:b74591d5ab33 175 mbedtls_mpi_init( &h );
be_bryan 0:b74591d5ab33 176 mbedtls_hmac_drbg_init( &rng_ctx );
be_bryan 0:b74591d5ab33 177
be_bryan 0:b74591d5ab33 178 /* Use private key and message hash (reduced) to initialize HMAC_DRBG */
be_bryan 0:b74591d5ab33 179 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( d, data, grp_len ) );
be_bryan 0:b74591d5ab33 180 MBEDTLS_MPI_CHK( derive_mpi( grp, &h, buf, blen ) );
be_bryan 0:b74591d5ab33 181 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &h, data + grp_len, grp_len ) );
be_bryan 0:b74591d5ab33 182 mbedtls_hmac_drbg_seed_buf( &rng_ctx, md_info, data, 2 * grp_len );
be_bryan 0:b74591d5ab33 183
be_bryan 0:b74591d5ab33 184 ret = mbedtls_ecdsa_sign( grp, r, s, d, buf, blen,
be_bryan 0:b74591d5ab33 185 mbedtls_hmac_drbg_random, &rng_ctx );
be_bryan 0:b74591d5ab33 186
be_bryan 0:b74591d5ab33 187 cleanup:
be_bryan 0:b74591d5ab33 188 mbedtls_hmac_drbg_free( &rng_ctx );
be_bryan 0:b74591d5ab33 189 mbedtls_mpi_free( &h );
be_bryan 0:b74591d5ab33 190
be_bryan 0:b74591d5ab33 191 return( ret );
be_bryan 0:b74591d5ab33 192 }
be_bryan 0:b74591d5ab33 193 #endif /* MBEDTLS_ECDSA_DETERMINISTIC */
be_bryan 0:b74591d5ab33 194
be_bryan 0:b74591d5ab33 195 /*
be_bryan 0:b74591d5ab33 196 * Verify ECDSA signature of hashed message (SEC1 4.1.4)
be_bryan 0:b74591d5ab33 197 * Obviously, compared to SEC1 4.1.3, we skip step 2 (hash message)
be_bryan 0:b74591d5ab33 198 */
be_bryan 0:b74591d5ab33 199 int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp,
be_bryan 0:b74591d5ab33 200 const unsigned char *buf, size_t blen,
be_bryan 0:b74591d5ab33 201 const mbedtls_ecp_point *Q, const mbedtls_mpi *r, const mbedtls_mpi *s)
be_bryan 0:b74591d5ab33 202 {
be_bryan 0:b74591d5ab33 203 int ret;
be_bryan 0:b74591d5ab33 204 mbedtls_mpi e, s_inv, u1, u2;
be_bryan 0:b74591d5ab33 205 mbedtls_ecp_point R;
be_bryan 0:b74591d5ab33 206
be_bryan 0:b74591d5ab33 207 mbedtls_ecp_point_init( &R );
be_bryan 0:b74591d5ab33 208 mbedtls_mpi_init( &e ); mbedtls_mpi_init( &s_inv ); mbedtls_mpi_init( &u1 ); mbedtls_mpi_init( &u2 );
be_bryan 0:b74591d5ab33 209
be_bryan 0:b74591d5ab33 210 /* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */
be_bryan 0:b74591d5ab33 211 if( grp->N.p == NULL )
be_bryan 0:b74591d5ab33 212 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
be_bryan 0:b74591d5ab33 213
be_bryan 0:b74591d5ab33 214 /*
be_bryan 0:b74591d5ab33 215 * Step 1: make sure r and s are in range 1..n-1
be_bryan 0:b74591d5ab33 216 */
be_bryan 0:b74591d5ab33 217 if( mbedtls_mpi_cmp_int( r, 1 ) < 0 || mbedtls_mpi_cmp_mpi( r, &grp->N ) >= 0 ||
be_bryan 0:b74591d5ab33 218 mbedtls_mpi_cmp_int( s, 1 ) < 0 || mbedtls_mpi_cmp_mpi( s, &grp->N ) >= 0 )
be_bryan 0:b74591d5ab33 219 {
be_bryan 0:b74591d5ab33 220 ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
be_bryan 0:b74591d5ab33 221 goto cleanup;
be_bryan 0:b74591d5ab33 222 }
be_bryan 0:b74591d5ab33 223
be_bryan 0:b74591d5ab33 224 /*
be_bryan 0:b74591d5ab33 225 * Additional precaution: make sure Q is valid
be_bryan 0:b74591d5ab33 226 */
be_bryan 0:b74591d5ab33 227 MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
be_bryan 0:b74591d5ab33 228
be_bryan 0:b74591d5ab33 229 /*
be_bryan 0:b74591d5ab33 230 * Step 3: derive MPI from hashed message
be_bryan 0:b74591d5ab33 231 */
be_bryan 0:b74591d5ab33 232 MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) );
be_bryan 0:b74591d5ab33 233
be_bryan 0:b74591d5ab33 234 /*
be_bryan 0:b74591d5ab33 235 * Step 4: u1 = e / s mod n, u2 = r / s mod n
be_bryan 0:b74591d5ab33 236 */
be_bryan 0:b74591d5ab33 237 MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &s_inv, s, &grp->N ) );
be_bryan 0:b74591d5ab33 238
be_bryan 0:b74591d5ab33 239 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &u1, &e, &s_inv ) );
be_bryan 0:b74591d5ab33 240 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &u1, &u1, &grp->N ) );
be_bryan 0:b74591d5ab33 241
be_bryan 0:b74591d5ab33 242 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &u2, r, &s_inv ) );
be_bryan 0:b74591d5ab33 243 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &u2, &u2, &grp->N ) );
be_bryan 0:b74591d5ab33 244
be_bryan 0:b74591d5ab33 245 /*
be_bryan 0:b74591d5ab33 246 * Step 5: R = u1 G + u2 Q
be_bryan 0:b74591d5ab33 247 *
be_bryan 0:b74591d5ab33 248 * Since we're not using any secret data, no need to pass a RNG to
be_bryan 0:b74591d5ab33 249 * mbedtls_ecp_mul() for countermesures.
be_bryan 0:b74591d5ab33 250 */
be_bryan 0:b74591d5ab33 251 MBEDTLS_MPI_CHK( mbedtls_ecp_muladd( grp, &R, &u1, &grp->G, &u2, Q ) );
be_bryan 0:b74591d5ab33 252
be_bryan 0:b74591d5ab33 253 if( mbedtls_ecp_is_zero( &R ) )
be_bryan 0:b74591d5ab33 254 {
be_bryan 0:b74591d5ab33 255 ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
be_bryan 0:b74591d5ab33 256 goto cleanup;
be_bryan 0:b74591d5ab33 257 }
be_bryan 0:b74591d5ab33 258
be_bryan 0:b74591d5ab33 259 /*
be_bryan 0:b74591d5ab33 260 * Step 6: convert xR to an integer (no-op)
be_bryan 0:b74591d5ab33 261 * Step 7: reduce xR mod n (gives v)
be_bryan 0:b74591d5ab33 262 */
be_bryan 0:b74591d5ab33 263 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &R.X, &R.X, &grp->N ) );
be_bryan 0:b74591d5ab33 264
be_bryan 0:b74591d5ab33 265 /*
be_bryan 0:b74591d5ab33 266 * Step 8: check if v (that is, R.X) is equal to r
be_bryan 0:b74591d5ab33 267 */
be_bryan 0:b74591d5ab33 268 if( mbedtls_mpi_cmp_mpi( &R.X, r ) != 0 )
be_bryan 0:b74591d5ab33 269 {
be_bryan 0:b74591d5ab33 270 ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
be_bryan 0:b74591d5ab33 271 goto cleanup;
be_bryan 0:b74591d5ab33 272 }
be_bryan 0:b74591d5ab33 273
be_bryan 0:b74591d5ab33 274 cleanup:
be_bryan 0:b74591d5ab33 275 mbedtls_ecp_point_free( &R );
be_bryan 0:b74591d5ab33 276 mbedtls_mpi_free( &e ); mbedtls_mpi_free( &s_inv ); mbedtls_mpi_free( &u1 ); mbedtls_mpi_free( &u2 );
be_bryan 0:b74591d5ab33 277
be_bryan 0:b74591d5ab33 278 return( ret );
be_bryan 0:b74591d5ab33 279 }
be_bryan 0:b74591d5ab33 280
be_bryan 0:b74591d5ab33 281 /*
be_bryan 0:b74591d5ab33 282 * Convert a signature (given by context) to ASN.1
be_bryan 0:b74591d5ab33 283 */
be_bryan 0:b74591d5ab33 284 static int ecdsa_signature_to_asn1( const mbedtls_mpi *r, const mbedtls_mpi *s,
be_bryan 0:b74591d5ab33 285 unsigned char *sig, size_t *slen )
be_bryan 0:b74591d5ab33 286 {
be_bryan 0:b74591d5ab33 287 int ret;
be_bryan 0:b74591d5ab33 288 unsigned char buf[MBEDTLS_ECDSA_MAX_LEN];
be_bryan 0:b74591d5ab33 289 unsigned char *p = buf + sizeof( buf );
be_bryan 0:b74591d5ab33 290 size_t len = 0;
be_bryan 0:b74591d5ab33 291
be_bryan 0:b74591d5ab33 292 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, s ) );
be_bryan 0:b74591d5ab33 293 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, r ) );
be_bryan 0:b74591d5ab33 294
be_bryan 0:b74591d5ab33 295 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &p, buf, len ) );
be_bryan 0:b74591d5ab33 296 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &p, buf,
be_bryan 0:b74591d5ab33 297 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
be_bryan 0:b74591d5ab33 298
be_bryan 0:b74591d5ab33 299 memcpy( sig, p, len );
be_bryan 0:b74591d5ab33 300 *slen = len;
be_bryan 0:b74591d5ab33 301
be_bryan 0:b74591d5ab33 302 return( 0 );
be_bryan 0:b74591d5ab33 303 }
be_bryan 0:b74591d5ab33 304
be_bryan 0:b74591d5ab33 305 /*
be_bryan 0:b74591d5ab33 306 * Compute and write signature
be_bryan 0:b74591d5ab33 307 */
be_bryan 0:b74591d5ab33 308 int mbedtls_ecdsa_write_signature( mbedtls_ecdsa_context *ctx, mbedtls_md_type_t md_alg,
be_bryan 0:b74591d5ab33 309 const unsigned char *hash, size_t hlen,
be_bryan 0:b74591d5ab33 310 unsigned char *sig, size_t *slen,
be_bryan 0:b74591d5ab33 311 int (*f_rng)(void *, unsigned char *, size_t),
be_bryan 0:b74591d5ab33 312 void *p_rng )
be_bryan 0:b74591d5ab33 313 {
be_bryan 0:b74591d5ab33 314 int ret;
be_bryan 0:b74591d5ab33 315 mbedtls_mpi r, s;
be_bryan 0:b74591d5ab33 316
be_bryan 0:b74591d5ab33 317 mbedtls_mpi_init( &r );
be_bryan 0:b74591d5ab33 318 mbedtls_mpi_init( &s );
be_bryan 0:b74591d5ab33 319
be_bryan 0:b74591d5ab33 320 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
be_bryan 0:b74591d5ab33 321 (void) f_rng;
be_bryan 0:b74591d5ab33 322 (void) p_rng;
be_bryan 0:b74591d5ab33 323
be_bryan 0:b74591d5ab33 324 MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign_det( &ctx->grp, &r, &s, &ctx->d,
be_bryan 0:b74591d5ab33 325 hash, hlen, md_alg ) );
be_bryan 0:b74591d5ab33 326 #else
be_bryan 0:b74591d5ab33 327 (void) md_alg;
be_bryan 0:b74591d5ab33 328
be_bryan 0:b74591d5ab33 329 MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign( &ctx->grp, &r, &s, &ctx->d,
be_bryan 0:b74591d5ab33 330 hash, hlen, f_rng, p_rng ) );
be_bryan 0:b74591d5ab33 331 #endif
be_bryan 0:b74591d5ab33 332
be_bryan 0:b74591d5ab33 333 MBEDTLS_MPI_CHK( ecdsa_signature_to_asn1( &r, &s, sig, slen ) );
be_bryan 0:b74591d5ab33 334
be_bryan 0:b74591d5ab33 335 cleanup:
be_bryan 0:b74591d5ab33 336 mbedtls_mpi_free( &r );
be_bryan 0:b74591d5ab33 337 mbedtls_mpi_free( &s );
be_bryan 0:b74591d5ab33 338
be_bryan 0:b74591d5ab33 339 return( ret );
be_bryan 0:b74591d5ab33 340 }
be_bryan 0:b74591d5ab33 341
be_bryan 0:b74591d5ab33 342 #if ! defined(MBEDTLS_DEPRECATED_REMOVED) && \
be_bryan 0:b74591d5ab33 343 defined(MBEDTLS_ECDSA_DETERMINISTIC)
be_bryan 0:b74591d5ab33 344 int mbedtls_ecdsa_write_signature_det( mbedtls_ecdsa_context *ctx,
be_bryan 0:b74591d5ab33 345 const unsigned char *hash, size_t hlen,
be_bryan 0:b74591d5ab33 346 unsigned char *sig, size_t *slen,
be_bryan 0:b74591d5ab33 347 mbedtls_md_type_t md_alg )
be_bryan 0:b74591d5ab33 348 {
be_bryan 0:b74591d5ab33 349 return( mbedtls_ecdsa_write_signature( ctx, md_alg, hash, hlen, sig, slen,
be_bryan 0:b74591d5ab33 350 NULL, NULL ) );
be_bryan 0:b74591d5ab33 351 }
be_bryan 0:b74591d5ab33 352 #endif
be_bryan 0:b74591d5ab33 353
be_bryan 0:b74591d5ab33 354 /*
be_bryan 0:b74591d5ab33 355 * Read and check signature
be_bryan 0:b74591d5ab33 356 */
be_bryan 0:b74591d5ab33 357 int mbedtls_ecdsa_read_signature( mbedtls_ecdsa_context *ctx,
be_bryan 0:b74591d5ab33 358 const unsigned char *hash, size_t hlen,
be_bryan 0:b74591d5ab33 359 const unsigned char *sig, size_t slen )
be_bryan 0:b74591d5ab33 360 {
be_bryan 0:b74591d5ab33 361 int ret;
be_bryan 0:b74591d5ab33 362 unsigned char *p = (unsigned char *) sig;
be_bryan 0:b74591d5ab33 363 const unsigned char *end = sig + slen;
be_bryan 0:b74591d5ab33 364 size_t len;
be_bryan 0:b74591d5ab33 365 mbedtls_mpi r, s;
be_bryan 0:b74591d5ab33 366
be_bryan 0:b74591d5ab33 367 mbedtls_mpi_init( &r );
be_bryan 0:b74591d5ab33 368 mbedtls_mpi_init( &s );
be_bryan 0:b74591d5ab33 369
be_bryan 0:b74591d5ab33 370 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
be_bryan 0:b74591d5ab33 371 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
be_bryan 0:b74591d5ab33 372 {
be_bryan 0:b74591d5ab33 373 ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
be_bryan 0:b74591d5ab33 374 goto cleanup;
be_bryan 0:b74591d5ab33 375 }
be_bryan 0:b74591d5ab33 376
be_bryan 0:b74591d5ab33 377 if( p + len != end )
be_bryan 0:b74591d5ab33 378 {
be_bryan 0:b74591d5ab33 379 ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA +
be_bryan 0:b74591d5ab33 380 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
be_bryan 0:b74591d5ab33 381 goto cleanup;
be_bryan 0:b74591d5ab33 382 }
be_bryan 0:b74591d5ab33 383
be_bryan 0:b74591d5ab33 384 if( ( ret = mbedtls_asn1_get_mpi( &p, end, &r ) ) != 0 ||
be_bryan 0:b74591d5ab33 385 ( ret = mbedtls_asn1_get_mpi( &p, end, &s ) ) != 0 )
be_bryan 0:b74591d5ab33 386 {
be_bryan 0:b74591d5ab33 387 ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
be_bryan 0:b74591d5ab33 388 goto cleanup;
be_bryan 0:b74591d5ab33 389 }
be_bryan 0:b74591d5ab33 390
be_bryan 0:b74591d5ab33 391 if( ( ret = mbedtls_ecdsa_verify( &ctx->grp, hash, hlen,
be_bryan 0:b74591d5ab33 392 &ctx->Q, &r, &s ) ) != 0 )
be_bryan 0:b74591d5ab33 393 goto cleanup;
be_bryan 0:b74591d5ab33 394
be_bryan 0:b74591d5ab33 395 if( p != end )
be_bryan 0:b74591d5ab33 396 ret = MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH;
be_bryan 0:b74591d5ab33 397
be_bryan 0:b74591d5ab33 398 cleanup:
be_bryan 0:b74591d5ab33 399 mbedtls_mpi_free( &r );
be_bryan 0:b74591d5ab33 400 mbedtls_mpi_free( &s );
be_bryan 0:b74591d5ab33 401
be_bryan 0:b74591d5ab33 402 return( ret );
be_bryan 0:b74591d5ab33 403 }
be_bryan 0:b74591d5ab33 404
be_bryan 0:b74591d5ab33 405 /*
be_bryan 0:b74591d5ab33 406 * Generate key pair
be_bryan 0:b74591d5ab33 407 */
be_bryan 0:b74591d5ab33 408 int mbedtls_ecdsa_genkey( mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id gid,
be_bryan 0:b74591d5ab33 409 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
be_bryan 0:b74591d5ab33 410 {
be_bryan 0:b74591d5ab33 411 return( mbedtls_ecp_group_load( &ctx->grp, gid ) ||
be_bryan 0:b74591d5ab33 412 mbedtls_ecp_gen_keypair( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) );
be_bryan 0:b74591d5ab33 413 }
be_bryan 0:b74591d5ab33 414
be_bryan 0:b74591d5ab33 415 /*
be_bryan 0:b74591d5ab33 416 * Set context from an mbedtls_ecp_keypair
be_bryan 0:b74591d5ab33 417 */
be_bryan 0:b74591d5ab33 418 int mbedtls_ecdsa_from_keypair( mbedtls_ecdsa_context *ctx, const mbedtls_ecp_keypair *key )
be_bryan 0:b74591d5ab33 419 {
be_bryan 0:b74591d5ab33 420 int ret;
be_bryan 0:b74591d5ab33 421
be_bryan 0:b74591d5ab33 422 if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 ||
be_bryan 0:b74591d5ab33 423 ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 ||
be_bryan 0:b74591d5ab33 424 ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 )
be_bryan 0:b74591d5ab33 425 {
be_bryan 0:b74591d5ab33 426 mbedtls_ecdsa_free( ctx );
be_bryan 0:b74591d5ab33 427 }
be_bryan 0:b74591d5ab33 428
be_bryan 0:b74591d5ab33 429 return( ret );
be_bryan 0:b74591d5ab33 430 }
be_bryan 0:b74591d5ab33 431
be_bryan 0:b74591d5ab33 432 /*
be_bryan 0:b74591d5ab33 433 * Initialize context
be_bryan 0:b74591d5ab33 434 */
be_bryan 0:b74591d5ab33 435 void mbedtls_ecdsa_init( mbedtls_ecdsa_context *ctx )
be_bryan 0:b74591d5ab33 436 {
be_bryan 0:b74591d5ab33 437 mbedtls_ecp_keypair_init( ctx );
be_bryan 0:b74591d5ab33 438 }
be_bryan 0:b74591d5ab33 439
be_bryan 0:b74591d5ab33 440 /*
be_bryan 0:b74591d5ab33 441 * Free context
be_bryan 0:b74591d5ab33 442 */
be_bryan 0:b74591d5ab33 443 void mbedtls_ecdsa_free( mbedtls_ecdsa_context *ctx )
be_bryan 0:b74591d5ab33 444 {
be_bryan 0:b74591d5ab33 445 mbedtls_ecp_keypair_free( ctx );
be_bryan 0:b74591d5ab33 446 }
be_bryan 0:b74591d5ab33 447
be_bryan 0:b74591d5ab33 448 #endif /* MBEDTLS_ECDSA_C */