Marco Zecchini / Mbed OS Example_RTOS

Rtos API example

mbed-os/features/mbedtls/src/ecdh.c@0:9fca2b23d0ba, 2019-02-23 (annotated)

Committer:
marcozecchini
Date:
Sat Feb 23 12:13:36 2019 +0000
Revision:
0:9fca2b23d0ba
final commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
marcozecchini 0:9fca2b23d0ba 1 /*
marcozecchini 0:9fca2b23d0ba 2 * Elliptic curve Diffie-Hellman
marcozecchini 0:9fca2b23d0ba 3 *
marcozecchini 0:9fca2b23d0ba 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
marcozecchini 0:9fca2b23d0ba 5 * SPDX-License-Identifier: Apache-2.0
marcozecchini 0:9fca2b23d0ba 6 *
marcozecchini 0:9fca2b23d0ba 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
marcozecchini 0:9fca2b23d0ba 8 * not use this file except in compliance with the License.
marcozecchini 0:9fca2b23d0ba 9 * You may obtain a copy of the License at
marcozecchini 0:9fca2b23d0ba 10 *
marcozecchini 0:9fca2b23d0ba 11 * http://www.apache.org/licenses/LICENSE-2.0
marcozecchini 0:9fca2b23d0ba 12 *
marcozecchini 0:9fca2b23d0ba 13 * Unless required by applicable law or agreed to in writing, software
marcozecchini 0:9fca2b23d0ba 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
marcozecchini 0:9fca2b23d0ba 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
marcozecchini 0:9fca2b23d0ba 16 * See the License for the specific language governing permissions and
marcozecchini 0:9fca2b23d0ba 17 * limitations under the License.
marcozecchini 0:9fca2b23d0ba 18 *
marcozecchini 0:9fca2b23d0ba 19 * This file is part of mbed TLS (https://tls.mbed.org)
marcozecchini 0:9fca2b23d0ba 20 */
marcozecchini 0:9fca2b23d0ba 21
marcozecchini 0:9fca2b23d0ba 22 /*
marcozecchini 0:9fca2b23d0ba 23 * References:
marcozecchini 0:9fca2b23d0ba 24 *
marcozecchini 0:9fca2b23d0ba 25 * SEC1 http://www.secg.org/index.php?action=secg,docs_secg
marcozecchini 0:9fca2b23d0ba 26 * RFC 4492
marcozecchini 0:9fca2b23d0ba 27 */
marcozecchini 0:9fca2b23d0ba 28
marcozecchini 0:9fca2b23d0ba 29 #if !defined(MBEDTLS_CONFIG_FILE)
marcozecchini 0:9fca2b23d0ba 30 #include "mbedtls/config.h"
marcozecchini 0:9fca2b23d0ba 31 #else
marcozecchini 0:9fca2b23d0ba 32 #include MBEDTLS_CONFIG_FILE
marcozecchini 0:9fca2b23d0ba 33 #endif
marcozecchini 0:9fca2b23d0ba 34
marcozecchini 0:9fca2b23d0ba 35 #if defined(MBEDTLS_ECDH_C)
marcozecchini 0:9fca2b23d0ba 36
marcozecchini 0:9fca2b23d0ba 37 #include "mbedtls/ecdh.h"
marcozecchini 0:9fca2b23d0ba 38
marcozecchini 0:9fca2b23d0ba 39 #include <string.h>
marcozecchini 0:9fca2b23d0ba 40
marcozecchini 0:9fca2b23d0ba 41 /*
marcozecchini 0:9fca2b23d0ba 42 * Generate public key: simple wrapper around mbedtls_ecp_gen_keypair
marcozecchini 0:9fca2b23d0ba 43 */
marcozecchini 0:9fca2b23d0ba 44 int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q,
marcozecchini 0:9fca2b23d0ba 45 int (*f_rng)(void *, unsigned char *, size_t),
marcozecchini 0:9fca2b23d0ba 46 void *p_rng )
marcozecchini 0:9fca2b23d0ba 47 {
marcozecchini 0:9fca2b23d0ba 48 return mbedtls_ecp_gen_keypair( grp, d, Q, f_rng, p_rng );
marcozecchini 0:9fca2b23d0ba 49 }
marcozecchini 0:9fca2b23d0ba 50
marcozecchini 0:9fca2b23d0ba 51 /*
marcozecchini 0:9fca2b23d0ba 52 * Compute shared secret (SEC1 3.3.1)
marcozecchini 0:9fca2b23d0ba 53 */
marcozecchini 0:9fca2b23d0ba 54 int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
marcozecchini 0:9fca2b23d0ba 55 const mbedtls_ecp_point *Q, const mbedtls_mpi *d,
marcozecchini 0:9fca2b23d0ba 56 int (*f_rng)(void *, unsigned char *, size_t),
marcozecchini 0:9fca2b23d0ba 57 void *p_rng )
marcozecchini 0:9fca2b23d0ba 58 {
marcozecchini 0:9fca2b23d0ba 59 int ret;
marcozecchini 0:9fca2b23d0ba 60 mbedtls_ecp_point P;
marcozecchini 0:9fca2b23d0ba 61
marcozecchini 0:9fca2b23d0ba 62 mbedtls_ecp_point_init( &P );
marcozecchini 0:9fca2b23d0ba 63
marcozecchini 0:9fca2b23d0ba 64 /*
marcozecchini 0:9fca2b23d0ba 65 * Make sure Q is a valid pubkey before using it
marcozecchini 0:9fca2b23d0ba 66 */
marcozecchini 0:9fca2b23d0ba 67 MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
marcozecchini 0:9fca2b23d0ba 68
marcozecchini 0:9fca2b23d0ba 69 MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, &P, d, Q, f_rng, p_rng ) );
marcozecchini 0:9fca2b23d0ba 70
marcozecchini 0:9fca2b23d0ba 71 if( mbedtls_ecp_is_zero( &P ) )
marcozecchini 0:9fca2b23d0ba 72 {
marcozecchini 0:9fca2b23d0ba 73 ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
marcozecchini 0:9fca2b23d0ba 74 goto cleanup;
marcozecchini 0:9fca2b23d0ba 75 }
marcozecchini 0:9fca2b23d0ba 76
marcozecchini 0:9fca2b23d0ba 77 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( z, &P.X ) );
marcozecchini 0:9fca2b23d0ba 78
marcozecchini 0:9fca2b23d0ba 79 cleanup:
marcozecchini 0:9fca2b23d0ba 80 mbedtls_ecp_point_free( &P );
marcozecchini 0:9fca2b23d0ba 81
marcozecchini 0:9fca2b23d0ba 82 return( ret );
marcozecchini 0:9fca2b23d0ba 83 }
marcozecchini 0:9fca2b23d0ba 84
marcozecchini 0:9fca2b23d0ba 85 /*
marcozecchini 0:9fca2b23d0ba 86 * Initialize context
marcozecchini 0:9fca2b23d0ba 87 */
marcozecchini 0:9fca2b23d0ba 88 void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx )
marcozecchini 0:9fca2b23d0ba 89 {
marcozecchini 0:9fca2b23d0ba 90 memset( ctx, 0, sizeof( mbedtls_ecdh_context ) );
marcozecchini 0:9fca2b23d0ba 91 }
marcozecchini 0:9fca2b23d0ba 92
marcozecchini 0:9fca2b23d0ba 93 /*
marcozecchini 0:9fca2b23d0ba 94 * Free context
marcozecchini 0:9fca2b23d0ba 95 */
marcozecchini 0:9fca2b23d0ba 96 void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx )
marcozecchini 0:9fca2b23d0ba 97 {
marcozecchini 0:9fca2b23d0ba 98 if( ctx == NULL )
marcozecchini 0:9fca2b23d0ba 99 return;
marcozecchini 0:9fca2b23d0ba 100
marcozecchini 0:9fca2b23d0ba 101 mbedtls_ecp_group_free( &ctx->grp );
marcozecchini 0:9fca2b23d0ba 102 mbedtls_ecp_point_free( &ctx->Q );
marcozecchini 0:9fca2b23d0ba 103 mbedtls_ecp_point_free( &ctx->Qp );
marcozecchini 0:9fca2b23d0ba 104 mbedtls_ecp_point_free( &ctx->Vi );
marcozecchini 0:9fca2b23d0ba 105 mbedtls_ecp_point_free( &ctx->Vf );
marcozecchini 0:9fca2b23d0ba 106 mbedtls_mpi_free( &ctx->d );
marcozecchini 0:9fca2b23d0ba 107 mbedtls_mpi_free( &ctx->z );
marcozecchini 0:9fca2b23d0ba 108 mbedtls_mpi_free( &ctx->_d );
marcozecchini 0:9fca2b23d0ba 109 }
marcozecchini 0:9fca2b23d0ba 110
marcozecchini 0:9fca2b23d0ba 111 /*
marcozecchini 0:9fca2b23d0ba 112 * Setup and write the ServerKeyExhange parameters (RFC 4492)
marcozecchini 0:9fca2b23d0ba 113 * struct {
marcozecchini 0:9fca2b23d0ba 114 * ECParameters curve_params;
marcozecchini 0:9fca2b23d0ba 115 * ECPoint public;
marcozecchini 0:9fca2b23d0ba 116 * } ServerECDHParams;
marcozecchini 0:9fca2b23d0ba 117 */
marcozecchini 0:9fca2b23d0ba 118 int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
marcozecchini 0:9fca2b23d0ba 119 unsigned char *buf, size_t blen,
marcozecchini 0:9fca2b23d0ba 120 int (*f_rng)(void *, unsigned char *, size_t),
marcozecchini 0:9fca2b23d0ba 121 void *p_rng )
marcozecchini 0:9fca2b23d0ba 122 {
marcozecchini 0:9fca2b23d0ba 123 int ret;
marcozecchini 0:9fca2b23d0ba 124 size_t grp_len, pt_len;
marcozecchini 0:9fca2b23d0ba 125
marcozecchini 0:9fca2b23d0ba 126 if( ctx == NULL || ctx->grp.pbits == 0 )
marcozecchini 0:9fca2b23d0ba 127 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
marcozecchini 0:9fca2b23d0ba 128
marcozecchini 0:9fca2b23d0ba 129 if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
marcozecchini 0:9fca2b23d0ba 130 != 0 )
marcozecchini 0:9fca2b23d0ba 131 return( ret );
marcozecchini 0:9fca2b23d0ba 132
marcozecchini 0:9fca2b23d0ba 133 if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf, blen ) )
marcozecchini 0:9fca2b23d0ba 134 != 0 )
marcozecchini 0:9fca2b23d0ba 135 return( ret );
marcozecchini 0:9fca2b23d0ba 136
marcozecchini 0:9fca2b23d0ba 137 buf += grp_len;
marcozecchini 0:9fca2b23d0ba 138 blen -= grp_len;
marcozecchini 0:9fca2b23d0ba 139
marcozecchini 0:9fca2b23d0ba 140 if( ( ret = mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
marcozecchini 0:9fca2b23d0ba 141 &pt_len, buf, blen ) ) != 0 )
marcozecchini 0:9fca2b23d0ba 142 return( ret );
marcozecchini 0:9fca2b23d0ba 143
marcozecchini 0:9fca2b23d0ba 144 *olen = grp_len + pt_len;
marcozecchini 0:9fca2b23d0ba 145 return( 0 );
marcozecchini 0:9fca2b23d0ba 146 }
marcozecchini 0:9fca2b23d0ba 147
marcozecchini 0:9fca2b23d0ba 148 /*
marcozecchini 0:9fca2b23d0ba 149 * Read the ServerKeyExhange parameters (RFC 4492)
marcozecchini 0:9fca2b23d0ba 150 * struct {
marcozecchini 0:9fca2b23d0ba 151 * ECParameters curve_params;
marcozecchini 0:9fca2b23d0ba 152 * ECPoint public;
marcozecchini 0:9fca2b23d0ba 153 * } ServerECDHParams;
marcozecchini 0:9fca2b23d0ba 154 */
marcozecchini 0:9fca2b23d0ba 155 int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
marcozecchini 0:9fca2b23d0ba 156 const unsigned char **buf, const unsigned char *end )
marcozecchini 0:9fca2b23d0ba 157 {
marcozecchini 0:9fca2b23d0ba 158 int ret;
marcozecchini 0:9fca2b23d0ba 159
marcozecchini 0:9fca2b23d0ba 160 if( ( ret = mbedtls_ecp_tls_read_group( &ctx->grp, buf, end - *buf ) ) != 0 )
marcozecchini 0:9fca2b23d0ba 161 return( ret );
marcozecchini 0:9fca2b23d0ba 162
marcozecchini 0:9fca2b23d0ba 163 if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf, end - *buf ) )
marcozecchini 0:9fca2b23d0ba 164 != 0 )
marcozecchini 0:9fca2b23d0ba 165 return( ret );
marcozecchini 0:9fca2b23d0ba 166
marcozecchini 0:9fca2b23d0ba 167 return( 0 );
marcozecchini 0:9fca2b23d0ba 168 }
marcozecchini 0:9fca2b23d0ba 169
marcozecchini 0:9fca2b23d0ba 170 /*
marcozecchini 0:9fca2b23d0ba 171 * Get parameters from a keypair
marcozecchini 0:9fca2b23d0ba 172 */
marcozecchini 0:9fca2b23d0ba 173 int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key,
marcozecchini 0:9fca2b23d0ba 174 mbedtls_ecdh_side side )
marcozecchini 0:9fca2b23d0ba 175 {
marcozecchini 0:9fca2b23d0ba 176 int ret;
marcozecchini 0:9fca2b23d0ba 177
marcozecchini 0:9fca2b23d0ba 178 if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 )
marcozecchini 0:9fca2b23d0ba 179 return( ret );
marcozecchini 0:9fca2b23d0ba 180
marcozecchini 0:9fca2b23d0ba 181 /* If it's not our key, just import the public part as Qp */
marcozecchini 0:9fca2b23d0ba 182 if( side == MBEDTLS_ECDH_THEIRS )
marcozecchini 0:9fca2b23d0ba 183 return( mbedtls_ecp_copy( &ctx->Qp, &key->Q ) );
marcozecchini 0:9fca2b23d0ba 184
marcozecchini 0:9fca2b23d0ba 185 /* Our key: import public (as Q) and private parts */
marcozecchini 0:9fca2b23d0ba 186 if( side != MBEDTLS_ECDH_OURS )
marcozecchini 0:9fca2b23d0ba 187 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
marcozecchini 0:9fca2b23d0ba 188
marcozecchini 0:9fca2b23d0ba 189 if( ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 ||
marcozecchini 0:9fca2b23d0ba 190 ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 )
marcozecchini 0:9fca2b23d0ba 191 return( ret );
marcozecchini 0:9fca2b23d0ba 192
marcozecchini 0:9fca2b23d0ba 193 return( 0 );
marcozecchini 0:9fca2b23d0ba 194 }
marcozecchini 0:9fca2b23d0ba 195
marcozecchini 0:9fca2b23d0ba 196 /*
marcozecchini 0:9fca2b23d0ba 197 * Setup and export the client public value
marcozecchini 0:9fca2b23d0ba 198 */
marcozecchini 0:9fca2b23d0ba 199 int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
marcozecchini 0:9fca2b23d0ba 200 unsigned char *buf, size_t blen,
marcozecchini 0:9fca2b23d0ba 201 int (*f_rng)(void *, unsigned char *, size_t),
marcozecchini 0:9fca2b23d0ba 202 void *p_rng )
marcozecchini 0:9fca2b23d0ba 203 {
marcozecchini 0:9fca2b23d0ba 204 int ret;
marcozecchini 0:9fca2b23d0ba 205
marcozecchini 0:9fca2b23d0ba 206 if( ctx == NULL || ctx->grp.pbits == 0 )
marcozecchini 0:9fca2b23d0ba 207 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
marcozecchini 0:9fca2b23d0ba 208
marcozecchini 0:9fca2b23d0ba 209 if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
marcozecchini 0:9fca2b23d0ba 210 != 0 )
marcozecchini 0:9fca2b23d0ba 211 return( ret );
marcozecchini 0:9fca2b23d0ba 212
marcozecchini 0:9fca2b23d0ba 213 return mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
marcozecchini 0:9fca2b23d0ba 214 olen, buf, blen );
marcozecchini 0:9fca2b23d0ba 215 }
marcozecchini 0:9fca2b23d0ba 216
marcozecchini 0:9fca2b23d0ba 217 /*
marcozecchini 0:9fca2b23d0ba 218 * Parse and import the client's public value
marcozecchini 0:9fca2b23d0ba 219 */
marcozecchini 0:9fca2b23d0ba 220 int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
marcozecchini 0:9fca2b23d0ba 221 const unsigned char *buf, size_t blen )
marcozecchini 0:9fca2b23d0ba 222 {
marcozecchini 0:9fca2b23d0ba 223 int ret;
marcozecchini 0:9fca2b23d0ba 224 const unsigned char *p = buf;
marcozecchini 0:9fca2b23d0ba 225
marcozecchini 0:9fca2b23d0ba 226 if( ctx == NULL )
marcozecchini 0:9fca2b23d0ba 227 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
marcozecchini 0:9fca2b23d0ba 228
marcozecchini 0:9fca2b23d0ba 229 if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, &p, blen ) ) != 0 )
marcozecchini 0:9fca2b23d0ba 230 return( ret );
marcozecchini 0:9fca2b23d0ba 231
marcozecchini 0:9fca2b23d0ba 232 if( (size_t)( p - buf ) != blen )
marcozecchini 0:9fca2b23d0ba 233 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
marcozecchini 0:9fca2b23d0ba 234
marcozecchini 0:9fca2b23d0ba 235 return( 0 );
marcozecchini 0:9fca2b23d0ba 236 }
marcozecchini 0:9fca2b23d0ba 237
marcozecchini 0:9fca2b23d0ba 238 /*
marcozecchini 0:9fca2b23d0ba 239 * Derive and export the shared secret
marcozecchini 0:9fca2b23d0ba 240 */
marcozecchini 0:9fca2b23d0ba 241 int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
marcozecchini 0:9fca2b23d0ba 242 unsigned char *buf, size_t blen,
marcozecchini 0:9fca2b23d0ba 243 int (*f_rng)(void *, unsigned char *, size_t),
marcozecchini 0:9fca2b23d0ba 244 void *p_rng )
marcozecchini 0:9fca2b23d0ba 245 {
marcozecchini 0:9fca2b23d0ba 246 int ret;
marcozecchini 0:9fca2b23d0ba 247
marcozecchini 0:9fca2b23d0ba 248 if( ctx == NULL )
marcozecchini 0:9fca2b23d0ba 249 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
marcozecchini 0:9fca2b23d0ba 250
marcozecchini 0:9fca2b23d0ba 251 if( ( ret = mbedtls_ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp, &ctx->d,
marcozecchini 0:9fca2b23d0ba 252 f_rng, p_rng ) ) != 0 )
marcozecchini 0:9fca2b23d0ba 253 {
marcozecchini 0:9fca2b23d0ba 254 return( ret );
marcozecchini 0:9fca2b23d0ba 255 }
marcozecchini 0:9fca2b23d0ba 256
marcozecchini 0:9fca2b23d0ba 257 if( mbedtls_mpi_size( &ctx->z ) > blen )
marcozecchini 0:9fca2b23d0ba 258 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
marcozecchini 0:9fca2b23d0ba 259
marcozecchini 0:9fca2b23d0ba 260 *olen = ctx->grp.pbits / 8 + ( ( ctx->grp.pbits % 8 ) != 0 );
marcozecchini 0:9fca2b23d0ba 261 return mbedtls_mpi_write_binary( &ctx->z, buf, *olen );
marcozecchini 0:9fca2b23d0ba 262 }
marcozecchini 0:9fca2b23d0ba 263
marcozecchini 0:9fca2b23d0ba 264 #endif /* MBEDTLS_ECDH_C */