Nitin Shukla / LED_Demo

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Dependencies:   MAX44000 nexpaq_mdk

Fork of LED_Demo by Maxim nexpaq

mbd_os/features/mbedtls/src/ecdsa.c@1:55a6170b404f, 2016-09-17 (annotated)

Committer:
nexpaq
Date:
Sat Sep 17 16:32:05 2016 +0000
Revision:
1:55a6170b404f
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nexpaq 1:55a6170b404f 1 /*
nexpaq 1:55a6170b404f 2 * Elliptic curve DSA
nexpaq 1:55a6170b404f 3 *
nexpaq 1:55a6170b404f 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
nexpaq 1:55a6170b404f 5 * SPDX-License-Identifier: Apache-2.0
nexpaq 1:55a6170b404f 6 *
nexpaq 1:55a6170b404f 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
nexpaq 1:55a6170b404f 8 * not use this file except in compliance with the License.
nexpaq 1:55a6170b404f 9 * You may obtain a copy of the License at
nexpaq 1:55a6170b404f 10 *
nexpaq 1:55a6170b404f 11 * http://www.apache.org/licenses/LICENSE-2.0
nexpaq 1:55a6170b404f 12 *
nexpaq 1:55a6170b404f 13 * Unless required by applicable law or agreed to in writing, software
nexpaq 1:55a6170b404f 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
nexpaq 1:55a6170b404f 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
nexpaq 1:55a6170b404f 16 * See the License for the specific language governing permissions and
nexpaq 1:55a6170b404f 17 * limitations under the License.
nexpaq 1:55a6170b404f 18 *
nexpaq 1:55a6170b404f 19 * This file is part of mbed TLS (https://tls.mbed.org)
nexpaq 1:55a6170b404f 20 */
nexpaq 1:55a6170b404f 21
nexpaq 1:55a6170b404f 22 /*
nexpaq 1:55a6170b404f 23 * References:
nexpaq 1:55a6170b404f 24 *
nexpaq 1:55a6170b404f 25 * SEC1 http://www.secg.org/index.php?action=secg,docs_secg
nexpaq 1:55a6170b404f 26 */
nexpaq 1:55a6170b404f 27
nexpaq 1:55a6170b404f 28 #if !defined(MBEDTLS_CONFIG_FILE)
nexpaq 1:55a6170b404f 29 #include "mbedtls/config.h"
nexpaq 1:55a6170b404f 30 #else
nexpaq 1:55a6170b404f 31 #include MBEDTLS_CONFIG_FILE
nexpaq 1:55a6170b404f 32 #endif
nexpaq 1:55a6170b404f 33
nexpaq 1:55a6170b404f 34 #if defined(MBEDTLS_ECDSA_C)
nexpaq 1:55a6170b404f 35
nexpaq 1:55a6170b404f 36 #include "mbedtls/ecdsa.h"
nexpaq 1:55a6170b404f 37 #include "mbedtls/asn1write.h"
nexpaq 1:55a6170b404f 38
nexpaq 1:55a6170b404f 39 #include <string.h>
nexpaq 1:55a6170b404f 40
nexpaq 1:55a6170b404f 41 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
nexpaq 1:55a6170b404f 42 #include "mbedtls/hmac_drbg.h"
nexpaq 1:55a6170b404f 43 #endif
nexpaq 1:55a6170b404f 44
nexpaq 1:55a6170b404f 45 /*
nexpaq 1:55a6170b404f 46 * Derive a suitable integer for group grp from a buffer of length len
nexpaq 1:55a6170b404f 47 * SEC1 4.1.3 step 5 aka SEC1 4.1.4 step 3
nexpaq 1:55a6170b404f 48 */
nexpaq 1:55a6170b404f 49 static int derive_mpi( const mbedtls_ecp_group *grp, mbedtls_mpi *x,
nexpaq 1:55a6170b404f 50 const unsigned char *buf, size_t blen )
nexpaq 1:55a6170b404f 51 {
nexpaq 1:55a6170b404f 52 int ret;
nexpaq 1:55a6170b404f 53 size_t n_size = ( grp->nbits + 7 ) / 8;
nexpaq 1:55a6170b404f 54 size_t use_size = blen > n_size ? n_size : blen;
nexpaq 1:55a6170b404f 55
nexpaq 1:55a6170b404f 56 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( x, buf, use_size ) );
nexpaq 1:55a6170b404f 57 if( use_size * 8 > grp->nbits )
nexpaq 1:55a6170b404f 58 MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( x, use_size * 8 - grp->nbits ) );
nexpaq 1:55a6170b404f 59
nexpaq 1:55a6170b404f 60 /* While at it, reduce modulo N */
nexpaq 1:55a6170b404f 61 if( mbedtls_mpi_cmp_mpi( x, &grp->N ) >= 0 )
nexpaq 1:55a6170b404f 62 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( x, x, &grp->N ) );
nexpaq 1:55a6170b404f 63
nexpaq 1:55a6170b404f 64 cleanup:
nexpaq 1:55a6170b404f 65 return( ret );
nexpaq 1:55a6170b404f 66 }
nexpaq 1:55a6170b404f 67
nexpaq 1:55a6170b404f 68 /*
nexpaq 1:55a6170b404f 69 * Compute ECDSA signature of a hashed message (SEC1 4.1.3)
nexpaq 1:55a6170b404f 70 * Obviously, compared to SEC1 4.1.3, we skip step 4 (hash message)
nexpaq 1:55a6170b404f 71 */
nexpaq 1:55a6170b404f 72 int mbedtls_ecdsa_sign( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
nexpaq 1:55a6170b404f 73 const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
nexpaq 1:55a6170b404f 74 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
nexpaq 1:55a6170b404f 75 {
nexpaq 1:55a6170b404f 76 int ret, key_tries, sign_tries, blind_tries;
nexpaq 1:55a6170b404f 77 mbedtls_ecp_point R;
nexpaq 1:55a6170b404f 78 mbedtls_mpi k, e, t;
nexpaq 1:55a6170b404f 79
nexpaq 1:55a6170b404f 80 /* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */
nexpaq 1:55a6170b404f 81 if( grp->N.p == NULL )
nexpaq 1:55a6170b404f 82 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
nexpaq 1:55a6170b404f 83
nexpaq 1:55a6170b404f 84 mbedtls_ecp_point_init( &R );
nexpaq 1:55a6170b404f 85 mbedtls_mpi_init( &k ); mbedtls_mpi_init( &e ); mbedtls_mpi_init( &t );
nexpaq 1:55a6170b404f 86
nexpaq 1:55a6170b404f 87 sign_tries = 0;
nexpaq 1:55a6170b404f 88 do
nexpaq 1:55a6170b404f 89 {
nexpaq 1:55a6170b404f 90 /*
nexpaq 1:55a6170b404f 91 * Steps 1-3: generate a suitable ephemeral keypair
nexpaq 1:55a6170b404f 92 * and set r = xR mod n
nexpaq 1:55a6170b404f 93 */
nexpaq 1:55a6170b404f 94 key_tries = 0;
nexpaq 1:55a6170b404f 95 do
nexpaq 1:55a6170b404f 96 {
nexpaq 1:55a6170b404f 97 MBEDTLS_MPI_CHK( mbedtls_ecp_gen_keypair( grp, &k, &R, f_rng, p_rng ) );
nexpaq 1:55a6170b404f 98 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( r, &R.X, &grp->N ) );
nexpaq 1:55a6170b404f 99
nexpaq 1:55a6170b404f 100 if( key_tries++ > 10 )
nexpaq 1:55a6170b404f 101 {
nexpaq 1:55a6170b404f 102 ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
nexpaq 1:55a6170b404f 103 goto cleanup;
nexpaq 1:55a6170b404f 104 }
nexpaq 1:55a6170b404f 105 }
nexpaq 1:55a6170b404f 106 while( mbedtls_mpi_cmp_int( r, 0 ) == 0 );
nexpaq 1:55a6170b404f 107
nexpaq 1:55a6170b404f 108 /*
nexpaq 1:55a6170b404f 109 * Step 5: derive MPI from hashed message
nexpaq 1:55a6170b404f 110 */
nexpaq 1:55a6170b404f 111 MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) );
nexpaq 1:55a6170b404f 112
nexpaq 1:55a6170b404f 113 /*
nexpaq 1:55a6170b404f 114 * Generate a random value to blind inv_mod in next step,
nexpaq 1:55a6170b404f 115 * avoiding a potential timing leak.
nexpaq 1:55a6170b404f 116 */
nexpaq 1:55a6170b404f 117 blind_tries = 0;
nexpaq 1:55a6170b404f 118 do
nexpaq 1:55a6170b404f 119 {
nexpaq 1:55a6170b404f 120 size_t n_size = ( grp->nbits + 7 ) / 8;
nexpaq 1:55a6170b404f 121 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &t, n_size, f_rng, p_rng ) );
nexpaq 1:55a6170b404f 122 MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &t, 8 * n_size - grp->nbits ) );
nexpaq 1:55a6170b404f 123
nexpaq 1:55a6170b404f 124 /* See mbedtls_ecp_gen_keypair() */
nexpaq 1:55a6170b404f 125 if( ++blind_tries > 30 )
nexpaq 1:55a6170b404f 126 return( MBEDTLS_ERR_ECP_RANDOM_FAILED );
nexpaq 1:55a6170b404f 127 }
nexpaq 1:55a6170b404f 128 while( mbedtls_mpi_cmp_int( &t, 1 ) < 0 ||
nexpaq 1:55a6170b404f 129 mbedtls_mpi_cmp_mpi( &t, &grp->N ) >= 0 );
nexpaq 1:55a6170b404f 130
nexpaq 1:55a6170b404f 131 /*
nexpaq 1:55a6170b404f 132 * Step 6: compute s = (e + r * d) / k = t (e + rd) / (kt) mod n
nexpaq 1:55a6170b404f 133 */
nexpaq 1:55a6170b404f 134 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, r, d ) );
nexpaq 1:55a6170b404f 135 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &e, &e, s ) );
nexpaq 1:55a6170b404f 136 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &e, &e, &t ) );
nexpaq 1:55a6170b404f 137 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &k, &k, &t ) );
nexpaq 1:55a6170b404f 138 MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( s, &k, &grp->N ) );
nexpaq 1:55a6170b404f 139 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, s, &e ) );
nexpaq 1:55a6170b404f 140 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( s, s, &grp->N ) );
nexpaq 1:55a6170b404f 141
nexpaq 1:55a6170b404f 142 if( sign_tries++ > 10 )
nexpaq 1:55a6170b404f 143 {
nexpaq 1:55a6170b404f 144 ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
nexpaq 1:55a6170b404f 145 goto cleanup;
nexpaq 1:55a6170b404f 146 }
nexpaq 1:55a6170b404f 147 }
nexpaq 1:55a6170b404f 148 while( mbedtls_mpi_cmp_int( s, 0 ) == 0 );
nexpaq 1:55a6170b404f 149
nexpaq 1:55a6170b404f 150 cleanup:
nexpaq 1:55a6170b404f 151 mbedtls_ecp_point_free( &R );
nexpaq 1:55a6170b404f 152 mbedtls_mpi_free( &k ); mbedtls_mpi_free( &e ); mbedtls_mpi_free( &t );
nexpaq 1:55a6170b404f 153
nexpaq 1:55a6170b404f 154 return( ret );
nexpaq 1:55a6170b404f 155 }
nexpaq 1:55a6170b404f 156
nexpaq 1:55a6170b404f 157 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
nexpaq 1:55a6170b404f 158 /*
nexpaq 1:55a6170b404f 159 * Deterministic signature wrapper
nexpaq 1:55a6170b404f 160 */
nexpaq 1:55a6170b404f 161 int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
nexpaq 1:55a6170b404f 162 const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
nexpaq 1:55a6170b404f 163 mbedtls_md_type_t md_alg )
nexpaq 1:55a6170b404f 164 {
nexpaq 1:55a6170b404f 165 int ret;
nexpaq 1:55a6170b404f 166 mbedtls_hmac_drbg_context rng_ctx;
nexpaq 1:55a6170b404f 167 unsigned char data[2 * MBEDTLS_ECP_MAX_BYTES];
nexpaq 1:55a6170b404f 168 size_t grp_len = ( grp->nbits + 7 ) / 8;
nexpaq 1:55a6170b404f 169 const mbedtls_md_info_t *md_info;
nexpaq 1:55a6170b404f 170 mbedtls_mpi h;
nexpaq 1:55a6170b404f 171
nexpaq 1:55a6170b404f 172 if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) == NULL )
nexpaq 1:55a6170b404f 173 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
nexpaq 1:55a6170b404f 174
nexpaq 1:55a6170b404f 175 mbedtls_mpi_init( &h );
nexpaq 1:55a6170b404f 176 mbedtls_hmac_drbg_init( &rng_ctx );
nexpaq 1:55a6170b404f 177
nexpaq 1:55a6170b404f 178 /* Use private key and message hash (reduced) to initialize HMAC_DRBG */
nexpaq 1:55a6170b404f 179 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( d, data, grp_len ) );
nexpaq 1:55a6170b404f 180 MBEDTLS_MPI_CHK( derive_mpi( grp, &h, buf, blen ) );
nexpaq 1:55a6170b404f 181 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &h, data + grp_len, grp_len ) );
nexpaq 1:55a6170b404f 182 mbedtls_hmac_drbg_seed_buf( &rng_ctx, md_info, data, 2 * grp_len );
nexpaq 1:55a6170b404f 183
nexpaq 1:55a6170b404f 184 ret = mbedtls_ecdsa_sign( grp, r, s, d, buf, blen,
nexpaq 1:55a6170b404f 185 mbedtls_hmac_drbg_random, &rng_ctx );
nexpaq 1:55a6170b404f 186
nexpaq 1:55a6170b404f 187 cleanup:
nexpaq 1:55a6170b404f 188 mbedtls_hmac_drbg_free( &rng_ctx );
nexpaq 1:55a6170b404f 189 mbedtls_mpi_free( &h );
nexpaq 1:55a6170b404f 190
nexpaq 1:55a6170b404f 191 return( ret );
nexpaq 1:55a6170b404f 192 }
nexpaq 1:55a6170b404f 193 #endif /* MBEDTLS_ECDSA_DETERMINISTIC */
nexpaq 1:55a6170b404f 194
nexpaq 1:55a6170b404f 195 /*
nexpaq 1:55a6170b404f 196 * Verify ECDSA signature of hashed message (SEC1 4.1.4)
nexpaq 1:55a6170b404f 197 * Obviously, compared to SEC1 4.1.3, we skip step 2 (hash message)
nexpaq 1:55a6170b404f 198 */
nexpaq 1:55a6170b404f 199 int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp,
nexpaq 1:55a6170b404f 200 const unsigned char *buf, size_t blen,
nexpaq 1:55a6170b404f 201 const mbedtls_ecp_point *Q, const mbedtls_mpi *r, const mbedtls_mpi *s)
nexpaq 1:55a6170b404f 202 {
nexpaq 1:55a6170b404f 203 int ret;
nexpaq 1:55a6170b404f 204 mbedtls_mpi e, s_inv, u1, u2;
nexpaq 1:55a6170b404f 205 mbedtls_ecp_point R;
nexpaq 1:55a6170b404f 206
nexpaq 1:55a6170b404f 207 mbedtls_ecp_point_init( &R );
nexpaq 1:55a6170b404f 208 mbedtls_mpi_init( &e ); mbedtls_mpi_init( &s_inv ); mbedtls_mpi_init( &u1 ); mbedtls_mpi_init( &u2 );
nexpaq 1:55a6170b404f 209
nexpaq 1:55a6170b404f 210 /* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */
nexpaq 1:55a6170b404f 211 if( grp->N.p == NULL )
nexpaq 1:55a6170b404f 212 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
nexpaq 1:55a6170b404f 213
nexpaq 1:55a6170b404f 214 /*
nexpaq 1:55a6170b404f 215 * Step 1: make sure r and s are in range 1..n-1
nexpaq 1:55a6170b404f 216 */
nexpaq 1:55a6170b404f 217 if( mbedtls_mpi_cmp_int( r, 1 ) < 0 || mbedtls_mpi_cmp_mpi( r, &grp->N ) >= 0 ||
nexpaq 1:55a6170b404f 218 mbedtls_mpi_cmp_int( s, 1 ) < 0 || mbedtls_mpi_cmp_mpi( s, &grp->N ) >= 0 )
nexpaq 1:55a6170b404f 219 {
nexpaq 1:55a6170b404f 220 ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
nexpaq 1:55a6170b404f 221 goto cleanup;
nexpaq 1:55a6170b404f 222 }
nexpaq 1:55a6170b404f 223
nexpaq 1:55a6170b404f 224 /*
nexpaq 1:55a6170b404f 225 * Additional precaution: make sure Q is valid
nexpaq 1:55a6170b404f 226 */
nexpaq 1:55a6170b404f 227 MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
nexpaq 1:55a6170b404f 228
nexpaq 1:55a6170b404f 229 /*
nexpaq 1:55a6170b404f 230 * Step 3: derive MPI from hashed message
nexpaq 1:55a6170b404f 231 */
nexpaq 1:55a6170b404f 232 MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) );
nexpaq 1:55a6170b404f 233
nexpaq 1:55a6170b404f 234 /*
nexpaq 1:55a6170b404f 235 * Step 4: u1 = e / s mod n, u2 = r / s mod n
nexpaq 1:55a6170b404f 236 */
nexpaq 1:55a6170b404f 237 MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &s_inv, s, &grp->N ) );
nexpaq 1:55a6170b404f 238
nexpaq 1:55a6170b404f 239 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &u1, &e, &s_inv ) );
nexpaq 1:55a6170b404f 240 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &u1, &u1, &grp->N ) );
nexpaq 1:55a6170b404f 241
nexpaq 1:55a6170b404f 242 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &u2, r, &s_inv ) );
nexpaq 1:55a6170b404f 243 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &u2, &u2, &grp->N ) );
nexpaq 1:55a6170b404f 244
nexpaq 1:55a6170b404f 245 /*
nexpaq 1:55a6170b404f 246 * Step 5: R = u1 G + u2 Q
nexpaq 1:55a6170b404f 247 *
nexpaq 1:55a6170b404f 248 * Since we're not using any secret data, no need to pass a RNG to
nexpaq 1:55a6170b404f 249 * mbedtls_ecp_mul() for countermesures.
nexpaq 1:55a6170b404f 250 */
nexpaq 1:55a6170b404f 251 MBEDTLS_MPI_CHK( mbedtls_ecp_muladd( grp, &R, &u1, &grp->G, &u2, Q ) );
nexpaq 1:55a6170b404f 252
nexpaq 1:55a6170b404f 253 if( mbedtls_ecp_is_zero( &R ) )
nexpaq 1:55a6170b404f 254 {
nexpaq 1:55a6170b404f 255 ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
nexpaq 1:55a6170b404f 256 goto cleanup;
nexpaq 1:55a6170b404f 257 }
nexpaq 1:55a6170b404f 258
nexpaq 1:55a6170b404f 259 /*
nexpaq 1:55a6170b404f 260 * Step 6: convert xR to an integer (no-op)
nexpaq 1:55a6170b404f 261 * Step 7: reduce xR mod n (gives v)
nexpaq 1:55a6170b404f 262 */
nexpaq 1:55a6170b404f 263 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &R.X, &R.X, &grp->N ) );
nexpaq 1:55a6170b404f 264
nexpaq 1:55a6170b404f 265 /*
nexpaq 1:55a6170b404f 266 * Step 8: check if v (that is, R.X) is equal to r
nexpaq 1:55a6170b404f 267 */
nexpaq 1:55a6170b404f 268 if( mbedtls_mpi_cmp_mpi( &R.X, r ) != 0 )
nexpaq 1:55a6170b404f 269 {
nexpaq 1:55a6170b404f 270 ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
nexpaq 1:55a6170b404f 271 goto cleanup;
nexpaq 1:55a6170b404f 272 }
nexpaq 1:55a6170b404f 273
nexpaq 1:55a6170b404f 274 cleanup:
nexpaq 1:55a6170b404f 275 mbedtls_ecp_point_free( &R );
nexpaq 1:55a6170b404f 276 mbedtls_mpi_free( &e ); mbedtls_mpi_free( &s_inv ); mbedtls_mpi_free( &u1 ); mbedtls_mpi_free( &u2 );
nexpaq 1:55a6170b404f 277
nexpaq 1:55a6170b404f 278 return( ret );
nexpaq 1:55a6170b404f 279 }
nexpaq 1:55a6170b404f 280
nexpaq 1:55a6170b404f 281 /*
nexpaq 1:55a6170b404f 282 * Convert a signature (given by context) to ASN.1
nexpaq 1:55a6170b404f 283 */
nexpaq 1:55a6170b404f 284 static int ecdsa_signature_to_asn1( const mbedtls_mpi *r, const mbedtls_mpi *s,
nexpaq 1:55a6170b404f 285 unsigned char *sig, size_t *slen )
nexpaq 1:55a6170b404f 286 {
nexpaq 1:55a6170b404f 287 int ret;
nexpaq 1:55a6170b404f 288 unsigned char buf[MBEDTLS_ECDSA_MAX_LEN];
nexpaq 1:55a6170b404f 289 unsigned char *p = buf + sizeof( buf );
nexpaq 1:55a6170b404f 290 size_t len = 0;
nexpaq 1:55a6170b404f 291
nexpaq 1:55a6170b404f 292 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, s ) );
nexpaq 1:55a6170b404f 293 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, r ) );
nexpaq 1:55a6170b404f 294
nexpaq 1:55a6170b404f 295 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &p, buf, len ) );
nexpaq 1:55a6170b404f 296 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &p, buf,
nexpaq 1:55a6170b404f 297 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
nexpaq 1:55a6170b404f 298
nexpaq 1:55a6170b404f 299 memcpy( sig, p, len );
nexpaq 1:55a6170b404f 300 *slen = len;
nexpaq 1:55a6170b404f 301
nexpaq 1:55a6170b404f 302 return( 0 );
nexpaq 1:55a6170b404f 303 }
nexpaq 1:55a6170b404f 304
nexpaq 1:55a6170b404f 305 /*
nexpaq 1:55a6170b404f 306 * Compute and write signature
nexpaq 1:55a6170b404f 307 */
nexpaq 1:55a6170b404f 308 int mbedtls_ecdsa_write_signature( mbedtls_ecdsa_context *ctx, mbedtls_md_type_t md_alg,
nexpaq 1:55a6170b404f 309 const unsigned char *hash, size_t hlen,
nexpaq 1:55a6170b404f 310 unsigned char *sig, size_t *slen,
nexpaq 1:55a6170b404f 311 int (*f_rng)(void *, unsigned char *, size_t),
nexpaq 1:55a6170b404f 312 void *p_rng )
nexpaq 1:55a6170b404f 313 {
nexpaq 1:55a6170b404f 314 int ret;
nexpaq 1:55a6170b404f 315 mbedtls_mpi r, s;
nexpaq 1:55a6170b404f 316
nexpaq 1:55a6170b404f 317 mbedtls_mpi_init( &r );
nexpaq 1:55a6170b404f 318 mbedtls_mpi_init( &s );
nexpaq 1:55a6170b404f 319
nexpaq 1:55a6170b404f 320 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
nexpaq 1:55a6170b404f 321 (void) f_rng;
nexpaq 1:55a6170b404f 322 (void) p_rng;
nexpaq 1:55a6170b404f 323
nexpaq 1:55a6170b404f 324 MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign_det( &ctx->grp, &r, &s, &ctx->d,
nexpaq 1:55a6170b404f 325 hash, hlen, md_alg ) );
nexpaq 1:55a6170b404f 326 #else
nexpaq 1:55a6170b404f 327 (void) md_alg;
nexpaq 1:55a6170b404f 328
nexpaq 1:55a6170b404f 329 MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign( &ctx->grp, &r, &s, &ctx->d,
nexpaq 1:55a6170b404f 330 hash, hlen, f_rng, p_rng ) );
nexpaq 1:55a6170b404f 331 #endif
nexpaq 1:55a6170b404f 332
nexpaq 1:55a6170b404f 333 MBEDTLS_MPI_CHK( ecdsa_signature_to_asn1( &r, &s, sig, slen ) );
nexpaq 1:55a6170b404f 334
nexpaq 1:55a6170b404f 335 cleanup:
nexpaq 1:55a6170b404f 336 mbedtls_mpi_free( &r );
nexpaq 1:55a6170b404f 337 mbedtls_mpi_free( &s );
nexpaq 1:55a6170b404f 338
nexpaq 1:55a6170b404f 339 return( ret );
nexpaq 1:55a6170b404f 340 }
nexpaq 1:55a6170b404f 341
nexpaq 1:55a6170b404f 342 #if ! defined(MBEDTLS_DEPRECATED_REMOVED) && \
nexpaq 1:55a6170b404f 343 defined(MBEDTLS_ECDSA_DETERMINISTIC)
nexpaq 1:55a6170b404f 344 int mbedtls_ecdsa_write_signature_det( mbedtls_ecdsa_context *ctx,
nexpaq 1:55a6170b404f 345 const unsigned char *hash, size_t hlen,
nexpaq 1:55a6170b404f 346 unsigned char *sig, size_t *slen,
nexpaq 1:55a6170b404f 347 mbedtls_md_type_t md_alg )
nexpaq 1:55a6170b404f 348 {
nexpaq 1:55a6170b404f 349 return( mbedtls_ecdsa_write_signature( ctx, md_alg, hash, hlen, sig, slen,
nexpaq 1:55a6170b404f 350 NULL, NULL ) );
nexpaq 1:55a6170b404f 351 }
nexpaq 1:55a6170b404f 352 #endif
nexpaq 1:55a6170b404f 353
nexpaq 1:55a6170b404f 354 /*
nexpaq 1:55a6170b404f 355 * Read and check signature
nexpaq 1:55a6170b404f 356 */
nexpaq 1:55a6170b404f 357 int mbedtls_ecdsa_read_signature( mbedtls_ecdsa_context *ctx,
nexpaq 1:55a6170b404f 358 const unsigned char *hash, size_t hlen,
nexpaq 1:55a6170b404f 359 const unsigned char *sig, size_t slen )
nexpaq 1:55a6170b404f 360 {
nexpaq 1:55a6170b404f 361 int ret;
nexpaq 1:55a6170b404f 362 unsigned char *p = (unsigned char *) sig;
nexpaq 1:55a6170b404f 363 const unsigned char *end = sig + slen;
nexpaq 1:55a6170b404f 364 size_t len;
nexpaq 1:55a6170b404f 365 mbedtls_mpi r, s;
nexpaq 1:55a6170b404f 366
nexpaq 1:55a6170b404f 367 mbedtls_mpi_init( &r );
nexpaq 1:55a6170b404f 368 mbedtls_mpi_init( &s );
nexpaq 1:55a6170b404f 369
nexpaq 1:55a6170b404f 370 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
nexpaq 1:55a6170b404f 371 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
nexpaq 1:55a6170b404f 372 {
nexpaq 1:55a6170b404f 373 ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
nexpaq 1:55a6170b404f 374 goto cleanup;
nexpaq 1:55a6170b404f 375 }
nexpaq 1:55a6170b404f 376
nexpaq 1:55a6170b404f 377 if( p + len != end )
nexpaq 1:55a6170b404f 378 {
nexpaq 1:55a6170b404f 379 ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA +
nexpaq 1:55a6170b404f 380 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
nexpaq 1:55a6170b404f 381 goto cleanup;
nexpaq 1:55a6170b404f 382 }
nexpaq 1:55a6170b404f 383
nexpaq 1:55a6170b404f 384 if( ( ret = mbedtls_asn1_get_mpi( &p, end, &r ) ) != 0 ||
nexpaq 1:55a6170b404f 385 ( ret = mbedtls_asn1_get_mpi( &p, end, &s ) ) != 0 )
nexpaq 1:55a6170b404f 386 {
nexpaq 1:55a6170b404f 387 ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
nexpaq 1:55a6170b404f 388 goto cleanup;
nexpaq 1:55a6170b404f 389 }
nexpaq 1:55a6170b404f 390
nexpaq 1:55a6170b404f 391 if( ( ret = mbedtls_ecdsa_verify( &ctx->grp, hash, hlen,
nexpaq 1:55a6170b404f 392 &ctx->Q, &r, &s ) ) != 0 )
nexpaq 1:55a6170b404f 393 goto cleanup;
nexpaq 1:55a6170b404f 394
nexpaq 1:55a6170b404f 395 if( p != end )
nexpaq 1:55a6170b404f 396 ret = MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH;
nexpaq 1:55a6170b404f 397
nexpaq 1:55a6170b404f 398 cleanup:
nexpaq 1:55a6170b404f 399 mbedtls_mpi_free( &r );
nexpaq 1:55a6170b404f 400 mbedtls_mpi_free( &s );
nexpaq 1:55a6170b404f 401
nexpaq 1:55a6170b404f 402 return( ret );
nexpaq 1:55a6170b404f 403 }
nexpaq 1:55a6170b404f 404
nexpaq 1:55a6170b404f 405 /*
nexpaq 1:55a6170b404f 406 * Generate key pair
nexpaq 1:55a6170b404f 407 */
nexpaq 1:55a6170b404f 408 int mbedtls_ecdsa_genkey( mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id gid,
nexpaq 1:55a6170b404f 409 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
nexpaq 1:55a6170b404f 410 {
nexpaq 1:55a6170b404f 411 return( mbedtls_ecp_group_load( &ctx->grp, gid ) ||
nexpaq 1:55a6170b404f 412 mbedtls_ecp_gen_keypair( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) );
nexpaq 1:55a6170b404f 413 }
nexpaq 1:55a6170b404f 414
nexpaq 1:55a6170b404f 415 /*
nexpaq 1:55a6170b404f 416 * Set context from an mbedtls_ecp_keypair
nexpaq 1:55a6170b404f 417 */
nexpaq 1:55a6170b404f 418 int mbedtls_ecdsa_from_keypair( mbedtls_ecdsa_context *ctx, const mbedtls_ecp_keypair *key )
nexpaq 1:55a6170b404f 419 {
nexpaq 1:55a6170b404f 420 int ret;
nexpaq 1:55a6170b404f 421
nexpaq 1:55a6170b404f 422 if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 ||
nexpaq 1:55a6170b404f 423 ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 ||
nexpaq 1:55a6170b404f 424 ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 )
nexpaq 1:55a6170b404f 425 {
nexpaq 1:55a6170b404f 426 mbedtls_ecdsa_free( ctx );
nexpaq 1:55a6170b404f 427 }
nexpaq 1:55a6170b404f 428
nexpaq 1:55a6170b404f 429 return( ret );
nexpaq 1:55a6170b404f 430 }
nexpaq 1:55a6170b404f 431
nexpaq 1:55a6170b404f 432 /*
nexpaq 1:55a6170b404f 433 * Initialize context
nexpaq 1:55a6170b404f 434 */
nexpaq 1:55a6170b404f 435 void mbedtls_ecdsa_init( mbedtls_ecdsa_context *ctx )
nexpaq 1:55a6170b404f 436 {
nexpaq 1:55a6170b404f 437 mbedtls_ecp_keypair_init( ctx );
nexpaq 1:55a6170b404f 438 }
nexpaq 1:55a6170b404f 439
nexpaq 1:55a6170b404f 440 /*
nexpaq 1:55a6170b404f 441 * Free context
nexpaq 1:55a6170b404f 442 */
nexpaq 1:55a6170b404f 443 void mbedtls_ecdsa_free( mbedtls_ecdsa_context *ctx )
nexpaq 1:55a6170b404f 444 {
nexpaq 1:55a6170b404f 445 mbedtls_ecp_keypair_free( ctx );
nexpaq 1:55a6170b404f 446 }
nexpaq 1:55a6170b404f 447
nexpaq 1:55a6170b404f 448 #endif /* MBEDTLS_ECDSA_C */