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mbed-os/features/mbedtls/src/ecdh.c@0:02dd72d1d465, 2018-04-24 (annotated)

Committer:
borlanic
Date:
Tue Apr 24 11:45:18 2018 +0000
Revision:
0:02dd72d1d465
BaBoRo_test2 - backup 1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
borlanic 0:02dd72d1d465 1 /*
borlanic 0:02dd72d1d465 2 * Elliptic curve Diffie-Hellman
borlanic 0:02dd72d1d465 3 *
borlanic 0:02dd72d1d465 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
borlanic 0:02dd72d1d465 5 * SPDX-License-Identifier: Apache-2.0
borlanic 0:02dd72d1d465 6 *
borlanic 0:02dd72d1d465 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
borlanic 0:02dd72d1d465 8 * not use this file except in compliance with the License.
borlanic 0:02dd72d1d465 9 * You may obtain a copy of the License at
borlanic 0:02dd72d1d465 10 *
borlanic 0:02dd72d1d465 11 * http://www.apache.org/licenses/LICENSE-2.0
borlanic 0:02dd72d1d465 12 *
borlanic 0:02dd72d1d465 13 * Unless required by applicable law or agreed to in writing, software
borlanic 0:02dd72d1d465 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
borlanic 0:02dd72d1d465 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
borlanic 0:02dd72d1d465 16 * See the License for the specific language governing permissions and
borlanic 0:02dd72d1d465 17 * limitations under the License.
borlanic 0:02dd72d1d465 18 *
borlanic 0:02dd72d1d465 19 * This file is part of mbed TLS (https://tls.mbed.org)
borlanic 0:02dd72d1d465 20 */
borlanic 0:02dd72d1d465 21
borlanic 0:02dd72d1d465 22 /*
borlanic 0:02dd72d1d465 23 * References:
borlanic 0:02dd72d1d465 24 *
borlanic 0:02dd72d1d465 25 * SEC1 http://www.secg.org/index.php?action=secg,docs_secg
borlanic 0:02dd72d1d465 26 * RFC 4492
borlanic 0:02dd72d1d465 27 */
borlanic 0:02dd72d1d465 28
borlanic 0:02dd72d1d465 29 #if !defined(MBEDTLS_CONFIG_FILE)
borlanic 0:02dd72d1d465 30 #include "mbedtls/config.h"
borlanic 0:02dd72d1d465 31 #else
borlanic 0:02dd72d1d465 32 #include MBEDTLS_CONFIG_FILE
borlanic 0:02dd72d1d465 33 #endif
borlanic 0:02dd72d1d465 34
borlanic 0:02dd72d1d465 35 #if defined(MBEDTLS_ECDH_C)
borlanic 0:02dd72d1d465 36
borlanic 0:02dd72d1d465 37 #include "mbedtls/ecdh.h"
borlanic 0:02dd72d1d465 38
borlanic 0:02dd72d1d465 39 #include <string.h>
borlanic 0:02dd72d1d465 40
borlanic 0:02dd72d1d465 41 #if !defined(MBEDTLS_ECDH_GEN_PUBLIC_ALT)
borlanic 0:02dd72d1d465 42 /*
borlanic 0:02dd72d1d465 43 * Generate public key: simple wrapper around mbedtls_ecp_gen_keypair
borlanic 0:02dd72d1d465 44 */
borlanic 0:02dd72d1d465 45 int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q,
borlanic 0:02dd72d1d465 46 int (*f_rng)(void *, unsigned char *, size_t),
borlanic 0:02dd72d1d465 47 void *p_rng )
borlanic 0:02dd72d1d465 48 {
borlanic 0:02dd72d1d465 49 return mbedtls_ecp_gen_keypair( grp, d, Q, f_rng, p_rng );
borlanic 0:02dd72d1d465 50 }
borlanic 0:02dd72d1d465 51 #endif /* MBEDTLS_ECDH_GEN_PUBLIC_ALT */
borlanic 0:02dd72d1d465 52
borlanic 0:02dd72d1d465 53 #if !defined(MBEDTLS_ECDH_COMPUTE_SHARED_ALT)
borlanic 0:02dd72d1d465 54 /*
borlanic 0:02dd72d1d465 55 * Compute shared secret (SEC1 3.3.1)
borlanic 0:02dd72d1d465 56 */
borlanic 0:02dd72d1d465 57 int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
borlanic 0:02dd72d1d465 58 const mbedtls_ecp_point *Q, const mbedtls_mpi *d,
borlanic 0:02dd72d1d465 59 int (*f_rng)(void *, unsigned char *, size_t),
borlanic 0:02dd72d1d465 60 void *p_rng )
borlanic 0:02dd72d1d465 61 {
borlanic 0:02dd72d1d465 62 int ret;
borlanic 0:02dd72d1d465 63 mbedtls_ecp_point P;
borlanic 0:02dd72d1d465 64
borlanic 0:02dd72d1d465 65 mbedtls_ecp_point_init( &P );
borlanic 0:02dd72d1d465 66
borlanic 0:02dd72d1d465 67 /*
borlanic 0:02dd72d1d465 68 * Make sure Q is a valid pubkey before using it
borlanic 0:02dd72d1d465 69 */
borlanic 0:02dd72d1d465 70 MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
borlanic 0:02dd72d1d465 71
borlanic 0:02dd72d1d465 72 MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, &P, d, Q, f_rng, p_rng ) );
borlanic 0:02dd72d1d465 73
borlanic 0:02dd72d1d465 74 if( mbedtls_ecp_is_zero( &P ) )
borlanic 0:02dd72d1d465 75 {
borlanic 0:02dd72d1d465 76 ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
borlanic 0:02dd72d1d465 77 goto cleanup;
borlanic 0:02dd72d1d465 78 }
borlanic 0:02dd72d1d465 79
borlanic 0:02dd72d1d465 80 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( z, &P.X ) );
borlanic 0:02dd72d1d465 81
borlanic 0:02dd72d1d465 82 cleanup:
borlanic 0:02dd72d1d465 83 mbedtls_ecp_point_free( &P );
borlanic 0:02dd72d1d465 84
borlanic 0:02dd72d1d465 85 return( ret );
borlanic 0:02dd72d1d465 86 }
borlanic 0:02dd72d1d465 87 #endif /* MBEDTLS_ECDH_COMPUTE_SHARED_ALT */
borlanic 0:02dd72d1d465 88
borlanic 0:02dd72d1d465 89 /*
borlanic 0:02dd72d1d465 90 * Initialize context
borlanic 0:02dd72d1d465 91 */
borlanic 0:02dd72d1d465 92 void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx )
borlanic 0:02dd72d1d465 93 {
borlanic 0:02dd72d1d465 94 memset( ctx, 0, sizeof( mbedtls_ecdh_context ) );
borlanic 0:02dd72d1d465 95 }
borlanic 0:02dd72d1d465 96
borlanic 0:02dd72d1d465 97 /*
borlanic 0:02dd72d1d465 98 * Free context
borlanic 0:02dd72d1d465 99 */
borlanic 0:02dd72d1d465 100 void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx )
borlanic 0:02dd72d1d465 101 {
borlanic 0:02dd72d1d465 102 if( ctx == NULL )
borlanic 0:02dd72d1d465 103 return;
borlanic 0:02dd72d1d465 104
borlanic 0:02dd72d1d465 105 mbedtls_ecp_group_free( &ctx->grp );
borlanic 0:02dd72d1d465 106 mbedtls_ecp_point_free( &ctx->Q );
borlanic 0:02dd72d1d465 107 mbedtls_ecp_point_free( &ctx->Qp );
borlanic 0:02dd72d1d465 108 mbedtls_ecp_point_free( &ctx->Vi );
borlanic 0:02dd72d1d465 109 mbedtls_ecp_point_free( &ctx->Vf );
borlanic 0:02dd72d1d465 110 mbedtls_mpi_free( &ctx->d );
borlanic 0:02dd72d1d465 111 mbedtls_mpi_free( &ctx->z );
borlanic 0:02dd72d1d465 112 mbedtls_mpi_free( &ctx->_d );
borlanic 0:02dd72d1d465 113 }
borlanic 0:02dd72d1d465 114
borlanic 0:02dd72d1d465 115 /*
borlanic 0:02dd72d1d465 116 * Setup and write the ServerKeyExhange parameters (RFC 4492)
borlanic 0:02dd72d1d465 117 * struct {
borlanic 0:02dd72d1d465 118 * ECParameters curve_params;
borlanic 0:02dd72d1d465 119 * ECPoint public;
borlanic 0:02dd72d1d465 120 * } ServerECDHParams;
borlanic 0:02dd72d1d465 121 */
borlanic 0:02dd72d1d465 122 int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
borlanic 0:02dd72d1d465 123 unsigned char *buf, size_t blen,
borlanic 0:02dd72d1d465 124 int (*f_rng)(void *, unsigned char *, size_t),
borlanic 0:02dd72d1d465 125 void *p_rng )
borlanic 0:02dd72d1d465 126 {
borlanic 0:02dd72d1d465 127 int ret;
borlanic 0:02dd72d1d465 128 size_t grp_len, pt_len;
borlanic 0:02dd72d1d465 129
borlanic 0:02dd72d1d465 130 if( ctx == NULL || ctx->grp.pbits == 0 )
borlanic 0:02dd72d1d465 131 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
borlanic 0:02dd72d1d465 132
borlanic 0:02dd72d1d465 133 if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
borlanic 0:02dd72d1d465 134 != 0 )
borlanic 0:02dd72d1d465 135 return( ret );
borlanic 0:02dd72d1d465 136
borlanic 0:02dd72d1d465 137 if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf, blen ) )
borlanic 0:02dd72d1d465 138 != 0 )
borlanic 0:02dd72d1d465 139 return( ret );
borlanic 0:02dd72d1d465 140
borlanic 0:02dd72d1d465 141 buf += grp_len;
borlanic 0:02dd72d1d465 142 blen -= grp_len;
borlanic 0:02dd72d1d465 143
borlanic 0:02dd72d1d465 144 if( ( ret = mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
borlanic 0:02dd72d1d465 145 &pt_len, buf, blen ) ) != 0 )
borlanic 0:02dd72d1d465 146 return( ret );
borlanic 0:02dd72d1d465 147
borlanic 0:02dd72d1d465 148 *olen = grp_len + pt_len;
borlanic 0:02dd72d1d465 149 return( 0 );
borlanic 0:02dd72d1d465 150 }
borlanic 0:02dd72d1d465 151
borlanic 0:02dd72d1d465 152 /*
borlanic 0:02dd72d1d465 153 * Read the ServerKeyExhange parameters (RFC 4492)
borlanic 0:02dd72d1d465 154 * struct {
borlanic 0:02dd72d1d465 155 * ECParameters curve_params;
borlanic 0:02dd72d1d465 156 * ECPoint public;
borlanic 0:02dd72d1d465 157 * } ServerECDHParams;
borlanic 0:02dd72d1d465 158 */
borlanic 0:02dd72d1d465 159 int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
borlanic 0:02dd72d1d465 160 const unsigned char **buf, const unsigned char *end )
borlanic 0:02dd72d1d465 161 {
borlanic 0:02dd72d1d465 162 int ret;
borlanic 0:02dd72d1d465 163
borlanic 0:02dd72d1d465 164 if( ( ret = mbedtls_ecp_tls_read_group( &ctx->grp, buf, end - *buf ) ) != 0 )
borlanic 0:02dd72d1d465 165 return( ret );
borlanic 0:02dd72d1d465 166
borlanic 0:02dd72d1d465 167 if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf, end - *buf ) )
borlanic 0:02dd72d1d465 168 != 0 )
borlanic 0:02dd72d1d465 169 return( ret );
borlanic 0:02dd72d1d465 170
borlanic 0:02dd72d1d465 171 return( 0 );
borlanic 0:02dd72d1d465 172 }
borlanic 0:02dd72d1d465 173
borlanic 0:02dd72d1d465 174 /*
borlanic 0:02dd72d1d465 175 * Get parameters from a keypair
borlanic 0:02dd72d1d465 176 */
borlanic 0:02dd72d1d465 177 int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key,
borlanic 0:02dd72d1d465 178 mbedtls_ecdh_side side )
borlanic 0:02dd72d1d465 179 {
borlanic 0:02dd72d1d465 180 int ret;
borlanic 0:02dd72d1d465 181
borlanic 0:02dd72d1d465 182 if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 )
borlanic 0:02dd72d1d465 183 return( ret );
borlanic 0:02dd72d1d465 184
borlanic 0:02dd72d1d465 185 /* If it's not our key, just import the public part as Qp */
borlanic 0:02dd72d1d465 186 if( side == MBEDTLS_ECDH_THEIRS )
borlanic 0:02dd72d1d465 187 return( mbedtls_ecp_copy( &ctx->Qp, &key->Q ) );
borlanic 0:02dd72d1d465 188
borlanic 0:02dd72d1d465 189 /* Our key: import public (as Q) and private parts */
borlanic 0:02dd72d1d465 190 if( side != MBEDTLS_ECDH_OURS )
borlanic 0:02dd72d1d465 191 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
borlanic 0:02dd72d1d465 192
borlanic 0:02dd72d1d465 193 if( ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 ||
borlanic 0:02dd72d1d465 194 ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 )
borlanic 0:02dd72d1d465 195 return( ret );
borlanic 0:02dd72d1d465 196
borlanic 0:02dd72d1d465 197 return( 0 );
borlanic 0:02dd72d1d465 198 }
borlanic 0:02dd72d1d465 199
borlanic 0:02dd72d1d465 200 /*
borlanic 0:02dd72d1d465 201 * Setup and export the client public value
borlanic 0:02dd72d1d465 202 */
borlanic 0:02dd72d1d465 203 int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
borlanic 0:02dd72d1d465 204 unsigned char *buf, size_t blen,
borlanic 0:02dd72d1d465 205 int (*f_rng)(void *, unsigned char *, size_t),
borlanic 0:02dd72d1d465 206 void *p_rng )
borlanic 0:02dd72d1d465 207 {
borlanic 0:02dd72d1d465 208 int ret;
borlanic 0:02dd72d1d465 209
borlanic 0:02dd72d1d465 210 if( ctx == NULL || ctx->grp.pbits == 0 )
borlanic 0:02dd72d1d465 211 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
borlanic 0:02dd72d1d465 212
borlanic 0:02dd72d1d465 213 if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
borlanic 0:02dd72d1d465 214 != 0 )
borlanic 0:02dd72d1d465 215 return( ret );
borlanic 0:02dd72d1d465 216
borlanic 0:02dd72d1d465 217 return mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
borlanic 0:02dd72d1d465 218 olen, buf, blen );
borlanic 0:02dd72d1d465 219 }
borlanic 0:02dd72d1d465 220
borlanic 0:02dd72d1d465 221 /*
borlanic 0:02dd72d1d465 222 * Parse and import the client's public value
borlanic 0:02dd72d1d465 223 */
borlanic 0:02dd72d1d465 224 int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
borlanic 0:02dd72d1d465 225 const unsigned char *buf, size_t blen )
borlanic 0:02dd72d1d465 226 {
borlanic 0:02dd72d1d465 227 int ret;
borlanic 0:02dd72d1d465 228 const unsigned char *p = buf;
borlanic 0:02dd72d1d465 229
borlanic 0:02dd72d1d465 230 if( ctx == NULL )
borlanic 0:02dd72d1d465 231 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
borlanic 0:02dd72d1d465 232
borlanic 0:02dd72d1d465 233 if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, &p, blen ) ) != 0 )
borlanic 0:02dd72d1d465 234 return( ret );
borlanic 0:02dd72d1d465 235
borlanic 0:02dd72d1d465 236 if( (size_t)( p - buf ) != blen )
borlanic 0:02dd72d1d465 237 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
borlanic 0:02dd72d1d465 238
borlanic 0:02dd72d1d465 239 return( 0 );
borlanic 0:02dd72d1d465 240 }
borlanic 0:02dd72d1d465 241
borlanic 0:02dd72d1d465 242 /*
borlanic 0:02dd72d1d465 243 * Derive and export the shared secret
borlanic 0:02dd72d1d465 244 */
borlanic 0:02dd72d1d465 245 int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
borlanic 0:02dd72d1d465 246 unsigned char *buf, size_t blen,
borlanic 0:02dd72d1d465 247 int (*f_rng)(void *, unsigned char *, size_t),
borlanic 0:02dd72d1d465 248 void *p_rng )
borlanic 0:02dd72d1d465 249 {
borlanic 0:02dd72d1d465 250 int ret;
borlanic 0:02dd72d1d465 251
borlanic 0:02dd72d1d465 252 if( ctx == NULL )
borlanic 0:02dd72d1d465 253 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
borlanic 0:02dd72d1d465 254
borlanic 0:02dd72d1d465 255 if( ( ret = mbedtls_ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp, &ctx->d,
borlanic 0:02dd72d1d465 256 f_rng, p_rng ) ) != 0 )
borlanic 0:02dd72d1d465 257 {
borlanic 0:02dd72d1d465 258 return( ret );
borlanic 0:02dd72d1d465 259 }
borlanic 0:02dd72d1d465 260
borlanic 0:02dd72d1d465 261 if( mbedtls_mpi_size( &ctx->z ) > blen )
borlanic 0:02dd72d1d465 262 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
borlanic 0:02dd72d1d465 263
borlanic 0:02dd72d1d465 264 *olen = ctx->grp.pbits / 8 + ( ( ctx->grp.pbits % 8 ) != 0 );
borlanic 0:02dd72d1d465 265 return mbedtls_mpi_write_binary( &ctx->z, buf, *olen );
borlanic 0:02dd72d1d465 266 }
borlanic 0:02dd72d1d465 267
borlanic 0:02dd72d1d465 268 #endif /* MBEDTLS_ECDH_C */