Austin Blackstone / Mbed 2 deprecated mbed-client-classic-example-lwip

mbed client on ethernet with LWIP

Dependencies:   mbed Socket lwip-eth lwip-sys lwip

Fork of mbed-client-classic-example-lwip by sandbox

mbedtls/source/ecdsa.c@11:cada08fc8a70, 2016-06-09 (annotated)

Committer:
mbedAustin
Date:
Thu Jun 09 17:08:36 2016 +0000
Revision:
11:cada08fc8a70
Commit for public Consumption

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbedAustin 11:cada08fc8a70 1 /*
mbedAustin 11:cada08fc8a70 2 * Elliptic curve DSA
mbedAustin 11:cada08fc8a70 3 *
mbedAustin 11:cada08fc8a70 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
mbedAustin 11:cada08fc8a70 5 * SPDX-License-Identifier: Apache-2.0
mbedAustin 11:cada08fc8a70 6 *
mbedAustin 11:cada08fc8a70 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
mbedAustin 11:cada08fc8a70 8 * not use this file except in compliance with the License.
mbedAustin 11:cada08fc8a70 9 * You may obtain a copy of the License at
mbedAustin 11:cada08fc8a70 10 *
mbedAustin 11:cada08fc8a70 11 * http://www.apache.org/licenses/LICENSE-2.0
mbedAustin 11:cada08fc8a70 12 *
mbedAustin 11:cada08fc8a70 13 * Unless required by applicable law or agreed to in writing, software
mbedAustin 11:cada08fc8a70 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
mbedAustin 11:cada08fc8a70 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbedAustin 11:cada08fc8a70 16 * See the License for the specific language governing permissions and
mbedAustin 11:cada08fc8a70 17 * limitations under the License.
mbedAustin 11:cada08fc8a70 18 *
mbedAustin 11:cada08fc8a70 19 * This file is part of mbed TLS (https://tls.mbed.org)
mbedAustin 11:cada08fc8a70 20 */
mbedAustin 11:cada08fc8a70 21
mbedAustin 11:cada08fc8a70 22 /*
mbedAustin 11:cada08fc8a70 23 * References:
mbedAustin 11:cada08fc8a70 24 *
mbedAustin 11:cada08fc8a70 25 * SEC1 http://www.secg.org/index.php?action=secg,docs_secg
mbedAustin 11:cada08fc8a70 26 */
mbedAustin 11:cada08fc8a70 27
mbedAustin 11:cada08fc8a70 28 #if !defined(MBEDTLS_CONFIG_FILE)
mbedAustin 11:cada08fc8a70 29 #include "mbedtls/config.h"
mbedAustin 11:cada08fc8a70 30 #else
mbedAustin 11:cada08fc8a70 31 #include MBEDTLS_CONFIG_FILE
mbedAustin 11:cada08fc8a70 32 #endif
mbedAustin 11:cada08fc8a70 33
mbedAustin 11:cada08fc8a70 34 #if defined(MBEDTLS_ECDSA_C)
mbedAustin 11:cada08fc8a70 35
mbedAustin 11:cada08fc8a70 36 #include "mbedtls/ecdsa.h"
mbedAustin 11:cada08fc8a70 37 #include "mbedtls/asn1write.h"
mbedAustin 11:cada08fc8a70 38
mbedAustin 11:cada08fc8a70 39 #include <string.h>
mbedAustin 11:cada08fc8a70 40
mbedAustin 11:cada08fc8a70 41 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
mbedAustin 11:cada08fc8a70 42 #include "mbedtls/hmac_drbg.h"
mbedAustin 11:cada08fc8a70 43 #endif
mbedAustin 11:cada08fc8a70 44
mbedAustin 11:cada08fc8a70 45 /*
mbedAustin 11:cada08fc8a70 46 * Derive a suitable integer for group grp from a buffer of length len
mbedAustin 11:cada08fc8a70 47 * SEC1 4.1.3 step 5 aka SEC1 4.1.4 step 3
mbedAustin 11:cada08fc8a70 48 */
mbedAustin 11:cada08fc8a70 49 static int derive_mpi( const mbedtls_ecp_group *grp, mbedtls_mpi *x,
mbedAustin 11:cada08fc8a70 50 const unsigned char *buf, size_t blen )
mbedAustin 11:cada08fc8a70 51 {
mbedAustin 11:cada08fc8a70 52 int ret;
mbedAustin 11:cada08fc8a70 53 size_t n_size = ( grp->nbits + 7 ) / 8;
mbedAustin 11:cada08fc8a70 54 size_t use_size = blen > n_size ? n_size : blen;
mbedAustin 11:cada08fc8a70 55
mbedAustin 11:cada08fc8a70 56 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( x, buf, use_size ) );
mbedAustin 11:cada08fc8a70 57 if( use_size * 8 > grp->nbits )
mbedAustin 11:cada08fc8a70 58 MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( x, use_size * 8 - grp->nbits ) );
mbedAustin 11:cada08fc8a70 59
mbedAustin 11:cada08fc8a70 60 /* While at it, reduce modulo N */
mbedAustin 11:cada08fc8a70 61 if( mbedtls_mpi_cmp_mpi( x, &grp->N ) >= 0 )
mbedAustin 11:cada08fc8a70 62 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( x, x, &grp->N ) );
mbedAustin 11:cada08fc8a70 63
mbedAustin 11:cada08fc8a70 64 cleanup:
mbedAustin 11:cada08fc8a70 65 return( ret );
mbedAustin 11:cada08fc8a70 66 }
mbedAustin 11:cada08fc8a70 67
mbedAustin 11:cada08fc8a70 68 /*
mbedAustin 11:cada08fc8a70 69 * Compute ECDSA signature of a hashed message (SEC1 4.1.3)
mbedAustin 11:cada08fc8a70 70 * Obviously, compared to SEC1 4.1.3, we skip step 4 (hash message)
mbedAustin 11:cada08fc8a70 71 */
mbedAustin 11:cada08fc8a70 72 int mbedtls_ecdsa_sign( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
mbedAustin 11:cada08fc8a70 73 const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
mbedAustin 11:cada08fc8a70 74 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
mbedAustin 11:cada08fc8a70 75 {
mbedAustin 11:cada08fc8a70 76 int ret, key_tries, sign_tries, blind_tries;
mbedAustin 11:cada08fc8a70 77 mbedtls_ecp_point R;
mbedAustin 11:cada08fc8a70 78 mbedtls_mpi k, e, t;
mbedAustin 11:cada08fc8a70 79
mbedAustin 11:cada08fc8a70 80 /* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */
mbedAustin 11:cada08fc8a70 81 if( grp->N.p == NULL )
mbedAustin 11:cada08fc8a70 82 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
mbedAustin 11:cada08fc8a70 83
mbedAustin 11:cada08fc8a70 84 mbedtls_ecp_point_init( &R );
mbedAustin 11:cada08fc8a70 85 mbedtls_mpi_init( &k ); mbedtls_mpi_init( &e ); mbedtls_mpi_init( &t );
mbedAustin 11:cada08fc8a70 86
mbedAustin 11:cada08fc8a70 87 sign_tries = 0;
mbedAustin 11:cada08fc8a70 88 do
mbedAustin 11:cada08fc8a70 89 {
mbedAustin 11:cada08fc8a70 90 /*
mbedAustin 11:cada08fc8a70 91 * Steps 1-3: generate a suitable ephemeral keypair
mbedAustin 11:cada08fc8a70 92 * and set r = xR mod n
mbedAustin 11:cada08fc8a70 93 */
mbedAustin 11:cada08fc8a70 94 key_tries = 0;
mbedAustin 11:cada08fc8a70 95 do
mbedAustin 11:cada08fc8a70 96 {
mbedAustin 11:cada08fc8a70 97 MBEDTLS_MPI_CHK( mbedtls_ecp_gen_keypair( grp, &k, &R, f_rng, p_rng ) );
mbedAustin 11:cada08fc8a70 98 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( r, &R.X, &grp->N ) );
mbedAustin 11:cada08fc8a70 99
mbedAustin 11:cada08fc8a70 100 if( key_tries++ > 10 )
mbedAustin 11:cada08fc8a70 101 {
mbedAustin 11:cada08fc8a70 102 ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
mbedAustin 11:cada08fc8a70 103 goto cleanup;
mbedAustin 11:cada08fc8a70 104 }
mbedAustin 11:cada08fc8a70 105 }
mbedAustin 11:cada08fc8a70 106 while( mbedtls_mpi_cmp_int( r, 0 ) == 0 );
mbedAustin 11:cada08fc8a70 107
mbedAustin 11:cada08fc8a70 108 /*
mbedAustin 11:cada08fc8a70 109 * Step 5: derive MPI from hashed message
mbedAustin 11:cada08fc8a70 110 */
mbedAustin 11:cada08fc8a70 111 MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) );
mbedAustin 11:cada08fc8a70 112
mbedAustin 11:cada08fc8a70 113 /*
mbedAustin 11:cada08fc8a70 114 * Generate a random value to blind inv_mod in next step,
mbedAustin 11:cada08fc8a70 115 * avoiding a potential timing leak.
mbedAustin 11:cada08fc8a70 116 */
mbedAustin 11:cada08fc8a70 117 blind_tries = 0;
mbedAustin 11:cada08fc8a70 118 do
mbedAustin 11:cada08fc8a70 119 {
mbedAustin 11:cada08fc8a70 120 size_t n_size = ( grp->nbits + 7 ) / 8;
mbedAustin 11:cada08fc8a70 121 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &t, n_size, f_rng, p_rng ) );
mbedAustin 11:cada08fc8a70 122 MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &t, 8 * n_size - grp->nbits ) );
mbedAustin 11:cada08fc8a70 123
mbedAustin 11:cada08fc8a70 124 /* See mbedtls_ecp_gen_keypair() */
mbedAustin 11:cada08fc8a70 125 if( ++blind_tries > 30 )
mbedAustin 11:cada08fc8a70 126 return( MBEDTLS_ERR_ECP_RANDOM_FAILED );
mbedAustin 11:cada08fc8a70 127 }
mbedAustin 11:cada08fc8a70 128 while( mbedtls_mpi_cmp_int( &t, 1 ) < 0 ||
mbedAustin 11:cada08fc8a70 129 mbedtls_mpi_cmp_mpi( &t, &grp->N ) >= 0 );
mbedAustin 11:cada08fc8a70 130
mbedAustin 11:cada08fc8a70 131 /*
mbedAustin 11:cada08fc8a70 132 * Step 6: compute s = (e + r * d) / k = t (e + rd) / (kt) mod n
mbedAustin 11:cada08fc8a70 133 */
mbedAustin 11:cada08fc8a70 134 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, r, d ) );
mbedAustin 11:cada08fc8a70 135 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &e, &e, s ) );
mbedAustin 11:cada08fc8a70 136 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &e, &e, &t ) );
mbedAustin 11:cada08fc8a70 137 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &k, &k, &t ) );
mbedAustin 11:cada08fc8a70 138 MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( s, &k, &grp->N ) );
mbedAustin 11:cada08fc8a70 139 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, s, &e ) );
mbedAustin 11:cada08fc8a70 140 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( s, s, &grp->N ) );
mbedAustin 11:cada08fc8a70 141
mbedAustin 11:cada08fc8a70 142 if( sign_tries++ > 10 )
mbedAustin 11:cada08fc8a70 143 {
mbedAustin 11:cada08fc8a70 144 ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
mbedAustin 11:cada08fc8a70 145 goto cleanup;
mbedAustin 11:cada08fc8a70 146 }
mbedAustin 11:cada08fc8a70 147 }
mbedAustin 11:cada08fc8a70 148 while( mbedtls_mpi_cmp_int( s, 0 ) == 0 );
mbedAustin 11:cada08fc8a70 149
mbedAustin 11:cada08fc8a70 150 cleanup:
mbedAustin 11:cada08fc8a70 151 mbedtls_ecp_point_free( &R );
mbedAustin 11:cada08fc8a70 152 mbedtls_mpi_free( &k ); mbedtls_mpi_free( &e ); mbedtls_mpi_free( &t );
mbedAustin 11:cada08fc8a70 153
mbedAustin 11:cada08fc8a70 154 return( ret );
mbedAustin 11:cada08fc8a70 155 }
mbedAustin 11:cada08fc8a70 156
mbedAustin 11:cada08fc8a70 157 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
mbedAustin 11:cada08fc8a70 158 /*
mbedAustin 11:cada08fc8a70 159 * Deterministic signature wrapper
mbedAustin 11:cada08fc8a70 160 */
mbedAustin 11:cada08fc8a70 161 int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
mbedAustin 11:cada08fc8a70 162 const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
mbedAustin 11:cada08fc8a70 163 mbedtls_md_type_t md_alg )
mbedAustin 11:cada08fc8a70 164 {
mbedAustin 11:cada08fc8a70 165 int ret;
mbedAustin 11:cada08fc8a70 166 mbedtls_hmac_drbg_context rng_ctx;
mbedAustin 11:cada08fc8a70 167 unsigned char data[2 * MBEDTLS_ECP_MAX_BYTES];
mbedAustin 11:cada08fc8a70 168 size_t grp_len = ( grp->nbits + 7 ) / 8;
mbedAustin 11:cada08fc8a70 169 const mbedtls_md_info_t *md_info;
mbedAustin 11:cada08fc8a70 170 mbedtls_mpi h;
mbedAustin 11:cada08fc8a70 171
mbedAustin 11:cada08fc8a70 172 if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) == NULL )
mbedAustin 11:cada08fc8a70 173 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
mbedAustin 11:cada08fc8a70 174
mbedAustin 11:cada08fc8a70 175 mbedtls_mpi_init( &h );
mbedAustin 11:cada08fc8a70 176 mbedtls_hmac_drbg_init( &rng_ctx );
mbedAustin 11:cada08fc8a70 177
mbedAustin 11:cada08fc8a70 178 /* Use private key and message hash (reduced) to initialize HMAC_DRBG */
mbedAustin 11:cada08fc8a70 179 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( d, data, grp_len ) );
mbedAustin 11:cada08fc8a70 180 MBEDTLS_MPI_CHK( derive_mpi( grp, &h, buf, blen ) );
mbedAustin 11:cada08fc8a70 181 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &h, data + grp_len, grp_len ) );
mbedAustin 11:cada08fc8a70 182 mbedtls_hmac_drbg_seed_buf( &rng_ctx, md_info, data, 2 * grp_len );
mbedAustin 11:cada08fc8a70 183
mbedAustin 11:cada08fc8a70 184 ret = mbedtls_ecdsa_sign( grp, r, s, d, buf, blen,
mbedAustin 11:cada08fc8a70 185 mbedtls_hmac_drbg_random, &rng_ctx );
mbedAustin 11:cada08fc8a70 186
mbedAustin 11:cada08fc8a70 187 cleanup:
mbedAustin 11:cada08fc8a70 188 mbedtls_hmac_drbg_free( &rng_ctx );
mbedAustin 11:cada08fc8a70 189 mbedtls_mpi_free( &h );
mbedAustin 11:cada08fc8a70 190
mbedAustin 11:cada08fc8a70 191 return( ret );
mbedAustin 11:cada08fc8a70 192 }
mbedAustin 11:cada08fc8a70 193 #endif /* MBEDTLS_ECDSA_DETERMINISTIC */
mbedAustin 11:cada08fc8a70 194
mbedAustin 11:cada08fc8a70 195 /*
mbedAustin 11:cada08fc8a70 196 * Verify ECDSA signature of hashed message (SEC1 4.1.4)
mbedAustin 11:cada08fc8a70 197 * Obviously, compared to SEC1 4.1.3, we skip step 2 (hash message)
mbedAustin 11:cada08fc8a70 198 */
mbedAustin 11:cada08fc8a70 199 int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp,
mbedAustin 11:cada08fc8a70 200 const unsigned char *buf, size_t blen,
mbedAustin 11:cada08fc8a70 201 const mbedtls_ecp_point *Q, const mbedtls_mpi *r, const mbedtls_mpi *s)
mbedAustin 11:cada08fc8a70 202 {
mbedAustin 11:cada08fc8a70 203 int ret;
mbedAustin 11:cada08fc8a70 204 mbedtls_mpi e, s_inv, u1, u2;
mbedAustin 11:cada08fc8a70 205 mbedtls_ecp_point R;
mbedAustin 11:cada08fc8a70 206
mbedAustin 11:cada08fc8a70 207 mbedtls_ecp_point_init( &R );
mbedAustin 11:cada08fc8a70 208 mbedtls_mpi_init( &e ); mbedtls_mpi_init( &s_inv ); mbedtls_mpi_init( &u1 ); mbedtls_mpi_init( &u2 );
mbedAustin 11:cada08fc8a70 209
mbedAustin 11:cada08fc8a70 210 /* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */
mbedAustin 11:cada08fc8a70 211 if( grp->N.p == NULL )
mbedAustin 11:cada08fc8a70 212 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
mbedAustin 11:cada08fc8a70 213
mbedAustin 11:cada08fc8a70 214 /*
mbedAustin 11:cada08fc8a70 215 * Step 1: make sure r and s are in range 1..n-1
mbedAustin 11:cada08fc8a70 216 */
mbedAustin 11:cada08fc8a70 217 if( mbedtls_mpi_cmp_int( r, 1 ) < 0 || mbedtls_mpi_cmp_mpi( r, &grp->N ) >= 0 ||
mbedAustin 11:cada08fc8a70 218 mbedtls_mpi_cmp_int( s, 1 ) < 0 || mbedtls_mpi_cmp_mpi( s, &grp->N ) >= 0 )
mbedAustin 11:cada08fc8a70 219 {
mbedAustin 11:cada08fc8a70 220 ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
mbedAustin 11:cada08fc8a70 221 goto cleanup;
mbedAustin 11:cada08fc8a70 222 }
mbedAustin 11:cada08fc8a70 223
mbedAustin 11:cada08fc8a70 224 /*
mbedAustin 11:cada08fc8a70 225 * Additional precaution: make sure Q is valid
mbedAustin 11:cada08fc8a70 226 */
mbedAustin 11:cada08fc8a70 227 MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
mbedAustin 11:cada08fc8a70 228
mbedAustin 11:cada08fc8a70 229 /*
mbedAustin 11:cada08fc8a70 230 * Step 3: derive MPI from hashed message
mbedAustin 11:cada08fc8a70 231 */
mbedAustin 11:cada08fc8a70 232 MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) );
mbedAustin 11:cada08fc8a70 233
mbedAustin 11:cada08fc8a70 234 /*
mbedAustin 11:cada08fc8a70 235 * Step 4: u1 = e / s mod n, u2 = r / s mod n
mbedAustin 11:cada08fc8a70 236 */
mbedAustin 11:cada08fc8a70 237 MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &s_inv, s, &grp->N ) );
mbedAustin 11:cada08fc8a70 238
mbedAustin 11:cada08fc8a70 239 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &u1, &e, &s_inv ) );
mbedAustin 11:cada08fc8a70 240 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &u1, &u1, &grp->N ) );
mbedAustin 11:cada08fc8a70 241
mbedAustin 11:cada08fc8a70 242 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &u2, r, &s_inv ) );
mbedAustin 11:cada08fc8a70 243 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &u2, &u2, &grp->N ) );
mbedAustin 11:cada08fc8a70 244
mbedAustin 11:cada08fc8a70 245 /*
mbedAustin 11:cada08fc8a70 246 * Step 5: R = u1 G + u2 Q
mbedAustin 11:cada08fc8a70 247 *
mbedAustin 11:cada08fc8a70 248 * Since we're not using any secret data, no need to pass a RNG to
mbedAustin 11:cada08fc8a70 249 * mbedtls_ecp_mul() for countermesures.
mbedAustin 11:cada08fc8a70 250 */
mbedAustin 11:cada08fc8a70 251 MBEDTLS_MPI_CHK( mbedtls_ecp_muladd( grp, &R, &u1, &grp->G, &u2, Q ) );
mbedAustin 11:cada08fc8a70 252
mbedAustin 11:cada08fc8a70 253 if( mbedtls_ecp_is_zero( &R ) )
mbedAustin 11:cada08fc8a70 254 {
mbedAustin 11:cada08fc8a70 255 ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
mbedAustin 11:cada08fc8a70 256 goto cleanup;
mbedAustin 11:cada08fc8a70 257 }
mbedAustin 11:cada08fc8a70 258
mbedAustin 11:cada08fc8a70 259 /*
mbedAustin 11:cada08fc8a70 260 * Step 6: convert xR to an integer (no-op)
mbedAustin 11:cada08fc8a70 261 * Step 7: reduce xR mod n (gives v)
mbedAustin 11:cada08fc8a70 262 */
mbedAustin 11:cada08fc8a70 263 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &R.X, &R.X, &grp->N ) );
mbedAustin 11:cada08fc8a70 264
mbedAustin 11:cada08fc8a70 265 /*
mbedAustin 11:cada08fc8a70 266 * Step 8: check if v (that is, R.X) is equal to r
mbedAustin 11:cada08fc8a70 267 */
mbedAustin 11:cada08fc8a70 268 if( mbedtls_mpi_cmp_mpi( &R.X, r ) != 0 )
mbedAustin 11:cada08fc8a70 269 {
mbedAustin 11:cada08fc8a70 270 ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
mbedAustin 11:cada08fc8a70 271 goto cleanup;
mbedAustin 11:cada08fc8a70 272 }
mbedAustin 11:cada08fc8a70 273
mbedAustin 11:cada08fc8a70 274 cleanup:
mbedAustin 11:cada08fc8a70 275 mbedtls_ecp_point_free( &R );
mbedAustin 11:cada08fc8a70 276 mbedtls_mpi_free( &e ); mbedtls_mpi_free( &s_inv ); mbedtls_mpi_free( &u1 ); mbedtls_mpi_free( &u2 );
mbedAustin 11:cada08fc8a70 277
mbedAustin 11:cada08fc8a70 278 return( ret );
mbedAustin 11:cada08fc8a70 279 }
mbedAustin 11:cada08fc8a70 280
mbedAustin 11:cada08fc8a70 281 /*
mbedAustin 11:cada08fc8a70 282 * Convert a signature (given by context) to ASN.1
mbedAustin 11:cada08fc8a70 283 */
mbedAustin 11:cada08fc8a70 284 static int ecdsa_signature_to_asn1( const mbedtls_mpi *r, const mbedtls_mpi *s,
mbedAustin 11:cada08fc8a70 285 unsigned char *sig, size_t *slen )
mbedAustin 11:cada08fc8a70 286 {
mbedAustin 11:cada08fc8a70 287 int ret;
mbedAustin 11:cada08fc8a70 288 unsigned char buf[MBEDTLS_ECDSA_MAX_LEN];
mbedAustin 11:cada08fc8a70 289 unsigned char *p = buf + sizeof( buf );
mbedAustin 11:cada08fc8a70 290 size_t len = 0;
mbedAustin 11:cada08fc8a70 291
mbedAustin 11:cada08fc8a70 292 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, s ) );
mbedAustin 11:cada08fc8a70 293 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, r ) );
mbedAustin 11:cada08fc8a70 294
mbedAustin 11:cada08fc8a70 295 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &p, buf, len ) );
mbedAustin 11:cada08fc8a70 296 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &p, buf,
mbedAustin 11:cada08fc8a70 297 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
mbedAustin 11:cada08fc8a70 298
mbedAustin 11:cada08fc8a70 299 memcpy( sig, p, len );
mbedAustin 11:cada08fc8a70 300 *slen = len;
mbedAustin 11:cada08fc8a70 301
mbedAustin 11:cada08fc8a70 302 return( 0 );
mbedAustin 11:cada08fc8a70 303 }
mbedAustin 11:cada08fc8a70 304
mbedAustin 11:cada08fc8a70 305 /*
mbedAustin 11:cada08fc8a70 306 * Compute and write signature
mbedAustin 11:cada08fc8a70 307 */
mbedAustin 11:cada08fc8a70 308 int mbedtls_ecdsa_write_signature( mbedtls_ecdsa_context *ctx, mbedtls_md_type_t md_alg,
mbedAustin 11:cada08fc8a70 309 const unsigned char *hash, size_t hlen,
mbedAustin 11:cada08fc8a70 310 unsigned char *sig, size_t *slen,
mbedAustin 11:cada08fc8a70 311 int (*f_rng)(void *, unsigned char *, size_t),
mbedAustin 11:cada08fc8a70 312 void *p_rng )
mbedAustin 11:cada08fc8a70 313 {
mbedAustin 11:cada08fc8a70 314 int ret;
mbedAustin 11:cada08fc8a70 315 mbedtls_mpi r, s;
mbedAustin 11:cada08fc8a70 316
mbedAustin 11:cada08fc8a70 317 mbedtls_mpi_init( &r );
mbedAustin 11:cada08fc8a70 318 mbedtls_mpi_init( &s );
mbedAustin 11:cada08fc8a70 319
mbedAustin 11:cada08fc8a70 320 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
mbedAustin 11:cada08fc8a70 321 (void) f_rng;
mbedAustin 11:cada08fc8a70 322 (void) p_rng;
mbedAustin 11:cada08fc8a70 323
mbedAustin 11:cada08fc8a70 324 MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign_det( &ctx->grp, &r, &s, &ctx->d,
mbedAustin 11:cada08fc8a70 325 hash, hlen, md_alg ) );
mbedAustin 11:cada08fc8a70 326 #else
mbedAustin 11:cada08fc8a70 327 (void) md_alg;
mbedAustin 11:cada08fc8a70 328
mbedAustin 11:cada08fc8a70 329 MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign( &ctx->grp, &r, &s, &ctx->d,
mbedAustin 11:cada08fc8a70 330 hash, hlen, f_rng, p_rng ) );
mbedAustin 11:cada08fc8a70 331 #endif
mbedAustin 11:cada08fc8a70 332
mbedAustin 11:cada08fc8a70 333 MBEDTLS_MPI_CHK( ecdsa_signature_to_asn1( &r, &s, sig, slen ) );
mbedAustin 11:cada08fc8a70 334
mbedAustin 11:cada08fc8a70 335 cleanup:
mbedAustin 11:cada08fc8a70 336 mbedtls_mpi_free( &r );
mbedAustin 11:cada08fc8a70 337 mbedtls_mpi_free( &s );
mbedAustin 11:cada08fc8a70 338
mbedAustin 11:cada08fc8a70 339 return( ret );
mbedAustin 11:cada08fc8a70 340 }
mbedAustin 11:cada08fc8a70 341
mbedAustin 11:cada08fc8a70 342 #if ! defined(MBEDTLS_DEPRECATED_REMOVED) && \
mbedAustin 11:cada08fc8a70 343 defined(MBEDTLS_ECDSA_DETERMINISTIC)
mbedAustin 11:cada08fc8a70 344 int mbedtls_ecdsa_write_signature_det( mbedtls_ecdsa_context *ctx,
mbedAustin 11:cada08fc8a70 345 const unsigned char *hash, size_t hlen,
mbedAustin 11:cada08fc8a70 346 unsigned char *sig, size_t *slen,
mbedAustin 11:cada08fc8a70 347 mbedtls_md_type_t md_alg )
mbedAustin 11:cada08fc8a70 348 {
mbedAustin 11:cada08fc8a70 349 return( mbedtls_ecdsa_write_signature( ctx, md_alg, hash, hlen, sig, slen,
mbedAustin 11:cada08fc8a70 350 NULL, NULL ) );
mbedAustin 11:cada08fc8a70 351 }
mbedAustin 11:cada08fc8a70 352 #endif
mbedAustin 11:cada08fc8a70 353
mbedAustin 11:cada08fc8a70 354 /*
mbedAustin 11:cada08fc8a70 355 * Read and check signature
mbedAustin 11:cada08fc8a70 356 */
mbedAustin 11:cada08fc8a70 357 int mbedtls_ecdsa_read_signature( mbedtls_ecdsa_context *ctx,
mbedAustin 11:cada08fc8a70 358 const unsigned char *hash, size_t hlen,
mbedAustin 11:cada08fc8a70 359 const unsigned char *sig, size_t slen )
mbedAustin 11:cada08fc8a70 360 {
mbedAustin 11:cada08fc8a70 361 int ret;
mbedAustin 11:cada08fc8a70 362 unsigned char *p = (unsigned char *) sig;
mbedAustin 11:cada08fc8a70 363 const unsigned char *end = sig + slen;
mbedAustin 11:cada08fc8a70 364 size_t len;
mbedAustin 11:cada08fc8a70 365 mbedtls_mpi r, s;
mbedAustin 11:cada08fc8a70 366
mbedAustin 11:cada08fc8a70 367 mbedtls_mpi_init( &r );
mbedAustin 11:cada08fc8a70 368 mbedtls_mpi_init( &s );
mbedAustin 11:cada08fc8a70 369
mbedAustin 11:cada08fc8a70 370 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
mbedAustin 11:cada08fc8a70 371 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
mbedAustin 11:cada08fc8a70 372 {
mbedAustin 11:cada08fc8a70 373 ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
mbedAustin 11:cada08fc8a70 374 goto cleanup;
mbedAustin 11:cada08fc8a70 375 }
mbedAustin 11:cada08fc8a70 376
mbedAustin 11:cada08fc8a70 377 if( p + len != end )
mbedAustin 11:cada08fc8a70 378 {
mbedAustin 11:cada08fc8a70 379 ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA +
mbedAustin 11:cada08fc8a70 380 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
mbedAustin 11:cada08fc8a70 381 goto cleanup;
mbedAustin 11:cada08fc8a70 382 }
mbedAustin 11:cada08fc8a70 383
mbedAustin 11:cada08fc8a70 384 if( ( ret = mbedtls_asn1_get_mpi( &p, end, &r ) ) != 0 ||
mbedAustin 11:cada08fc8a70 385 ( ret = mbedtls_asn1_get_mpi( &p, end, &s ) ) != 0 )
mbedAustin 11:cada08fc8a70 386 {
mbedAustin 11:cada08fc8a70 387 ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
mbedAustin 11:cada08fc8a70 388 goto cleanup;
mbedAustin 11:cada08fc8a70 389 }
mbedAustin 11:cada08fc8a70 390
mbedAustin 11:cada08fc8a70 391 if( ( ret = mbedtls_ecdsa_verify( &ctx->grp, hash, hlen,
mbedAustin 11:cada08fc8a70 392 &ctx->Q, &r, &s ) ) != 0 )
mbedAustin 11:cada08fc8a70 393 goto cleanup;
mbedAustin 11:cada08fc8a70 394
mbedAustin 11:cada08fc8a70 395 if( p != end )
mbedAustin 11:cada08fc8a70 396 ret = MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH;
mbedAustin 11:cada08fc8a70 397
mbedAustin 11:cada08fc8a70 398 cleanup:
mbedAustin 11:cada08fc8a70 399 mbedtls_mpi_free( &r );
mbedAustin 11:cada08fc8a70 400 mbedtls_mpi_free( &s );
mbedAustin 11:cada08fc8a70 401
mbedAustin 11:cada08fc8a70 402 return( ret );
mbedAustin 11:cada08fc8a70 403 }
mbedAustin 11:cada08fc8a70 404
mbedAustin 11:cada08fc8a70 405 /*
mbedAustin 11:cada08fc8a70 406 * Generate key pair
mbedAustin 11:cada08fc8a70 407 */
mbedAustin 11:cada08fc8a70 408 int mbedtls_ecdsa_genkey( mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id gid,
mbedAustin 11:cada08fc8a70 409 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
mbedAustin 11:cada08fc8a70 410 {
mbedAustin 11:cada08fc8a70 411 return( mbedtls_ecp_group_load( &ctx->grp, gid ) ||
mbedAustin 11:cada08fc8a70 412 mbedtls_ecp_gen_keypair( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) );
mbedAustin 11:cada08fc8a70 413 }
mbedAustin 11:cada08fc8a70 414
mbedAustin 11:cada08fc8a70 415 /*
mbedAustin 11:cada08fc8a70 416 * Set context from an mbedtls_ecp_keypair
mbedAustin 11:cada08fc8a70 417 */
mbedAustin 11:cada08fc8a70 418 int mbedtls_ecdsa_from_keypair( mbedtls_ecdsa_context *ctx, const mbedtls_ecp_keypair *key )
mbedAustin 11:cada08fc8a70 419 {
mbedAustin 11:cada08fc8a70 420 int ret;
mbedAustin 11:cada08fc8a70 421
mbedAustin 11:cada08fc8a70 422 if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 ||
mbedAustin 11:cada08fc8a70 423 ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 ||
mbedAustin 11:cada08fc8a70 424 ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 )
mbedAustin 11:cada08fc8a70 425 {
mbedAustin 11:cada08fc8a70 426 mbedtls_ecdsa_free( ctx );
mbedAustin 11:cada08fc8a70 427 }
mbedAustin 11:cada08fc8a70 428
mbedAustin 11:cada08fc8a70 429 return( ret );
mbedAustin 11:cada08fc8a70 430 }
mbedAustin 11:cada08fc8a70 431
mbedAustin 11:cada08fc8a70 432 /*
mbedAustin 11:cada08fc8a70 433 * Initialize context
mbedAustin 11:cada08fc8a70 434 */
mbedAustin 11:cada08fc8a70 435 void mbedtls_ecdsa_init( mbedtls_ecdsa_context *ctx )
mbedAustin 11:cada08fc8a70 436 {
mbedAustin 11:cada08fc8a70 437 mbedtls_ecp_keypair_init( ctx );
mbedAustin 11:cada08fc8a70 438 }
mbedAustin 11:cada08fc8a70 439
mbedAustin 11:cada08fc8a70 440 /*
mbedAustin 11:cada08fc8a70 441 * Free context
mbedAustin 11:cada08fc8a70 442 */
mbedAustin 11:cada08fc8a70 443 void mbedtls_ecdsa_free( mbedtls_ecdsa_context *ctx )
mbedAustin 11:cada08fc8a70 444 {
mbedAustin 11:cada08fc8a70 445 mbedtls_ecp_keypair_free( ctx );
mbedAustin 11:cada08fc8a70 446 }
mbedAustin 11:cada08fc8a70 447
mbedAustin 11:cada08fc8a70 448 #endif /* MBEDTLS_ECDSA_C */