Kev Mann / mbed-dev-OS5_10_4

RTC auf true

features/mbedtls/src/ecdh.c@0:38ceb79fef03, 2018-11-28 (annotated)

Committer:
kevman
Date:
Wed Nov 28 15:10:15 2018 +0000
Revision:
0:38ceb79fef03
RTC modified

Who changed what in which revision?

UserRevisionLine numberNew contents of line
kevman 0:38ceb79fef03 1 /*
kevman 0:38ceb79fef03 2 * Elliptic curve Diffie-Hellman
kevman 0:38ceb79fef03 3 *
kevman 0:38ceb79fef03 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
kevman 0:38ceb79fef03 5 * SPDX-License-Identifier: Apache-2.0
kevman 0:38ceb79fef03 6 *
kevman 0:38ceb79fef03 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
kevman 0:38ceb79fef03 8 * not use this file except in compliance with the License.
kevman 0:38ceb79fef03 9 * You may obtain a copy of the License at
kevman 0:38ceb79fef03 10 *
kevman 0:38ceb79fef03 11 * http://www.apache.org/licenses/LICENSE-2.0
kevman 0:38ceb79fef03 12 *
kevman 0:38ceb79fef03 13 * Unless required by applicable law or agreed to in writing, software
kevman 0:38ceb79fef03 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
kevman 0:38ceb79fef03 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
kevman 0:38ceb79fef03 16 * See the License for the specific language governing permissions and
kevman 0:38ceb79fef03 17 * limitations under the License.
kevman 0:38ceb79fef03 18 *
kevman 0:38ceb79fef03 19 * This file is part of mbed TLS (https://tls.mbed.org)
kevman 0:38ceb79fef03 20 */
kevman 0:38ceb79fef03 21
kevman 0:38ceb79fef03 22 /*
kevman 0:38ceb79fef03 23 * References:
kevman 0:38ceb79fef03 24 *
kevman 0:38ceb79fef03 25 * SEC1 http://www.secg.org/index.php?action=secg,docs_secg
kevman 0:38ceb79fef03 26 * RFC 4492
kevman 0:38ceb79fef03 27 */
kevman 0:38ceb79fef03 28
kevman 0:38ceb79fef03 29 #if !defined(MBEDTLS_CONFIG_FILE)
kevman 0:38ceb79fef03 30 #include "mbedtls/config.h"
kevman 0:38ceb79fef03 31 #else
kevman 0:38ceb79fef03 32 #include MBEDTLS_CONFIG_FILE
kevman 0:38ceb79fef03 33 #endif
kevman 0:38ceb79fef03 34
kevman 0:38ceb79fef03 35 #if defined(MBEDTLS_ECDH_C)
kevman 0:38ceb79fef03 36
kevman 0:38ceb79fef03 37 #include "mbedtls/ecdh.h"
kevman 0:38ceb79fef03 38
kevman 0:38ceb79fef03 39 #include <string.h>
kevman 0:38ceb79fef03 40
kevman 0:38ceb79fef03 41 #if !defined(MBEDTLS_ECDH_GEN_PUBLIC_ALT)
kevman 0:38ceb79fef03 42 /*
kevman 0:38ceb79fef03 43 * Generate public key: simple wrapper around mbedtls_ecp_gen_keypair
kevman 0:38ceb79fef03 44 */
kevman 0:38ceb79fef03 45 int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q,
kevman 0:38ceb79fef03 46 int (*f_rng)(void *, unsigned char *, size_t),
kevman 0:38ceb79fef03 47 void *p_rng )
kevman 0:38ceb79fef03 48 {
kevman 0:38ceb79fef03 49 return mbedtls_ecp_gen_keypair( grp, d, Q, f_rng, p_rng );
kevman 0:38ceb79fef03 50 }
kevman 0:38ceb79fef03 51 #endif /* MBEDTLS_ECDH_GEN_PUBLIC_ALT */
kevman 0:38ceb79fef03 52
kevman 0:38ceb79fef03 53 #if !defined(MBEDTLS_ECDH_COMPUTE_SHARED_ALT)
kevman 0:38ceb79fef03 54 /*
kevman 0:38ceb79fef03 55 * Compute shared secret (SEC1 3.3.1)
kevman 0:38ceb79fef03 56 */
kevman 0:38ceb79fef03 57 int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
kevman 0:38ceb79fef03 58 const mbedtls_ecp_point *Q, const mbedtls_mpi *d,
kevman 0:38ceb79fef03 59 int (*f_rng)(void *, unsigned char *, size_t),
kevman 0:38ceb79fef03 60 void *p_rng )
kevman 0:38ceb79fef03 61 {
kevman 0:38ceb79fef03 62 int ret;
kevman 0:38ceb79fef03 63 mbedtls_ecp_point P;
kevman 0:38ceb79fef03 64
kevman 0:38ceb79fef03 65 mbedtls_ecp_point_init( &P );
kevman 0:38ceb79fef03 66
kevman 0:38ceb79fef03 67 /*
kevman 0:38ceb79fef03 68 * Make sure Q is a valid pubkey before using it
kevman 0:38ceb79fef03 69 */
kevman 0:38ceb79fef03 70 MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
kevman 0:38ceb79fef03 71
kevman 0:38ceb79fef03 72 MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, &P, d, Q, f_rng, p_rng ) );
kevman 0:38ceb79fef03 73
kevman 0:38ceb79fef03 74 if( mbedtls_ecp_is_zero( &P ) )
kevman 0:38ceb79fef03 75 {
kevman 0:38ceb79fef03 76 ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
kevman 0:38ceb79fef03 77 goto cleanup;
kevman 0:38ceb79fef03 78 }
kevman 0:38ceb79fef03 79
kevman 0:38ceb79fef03 80 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( z, &P.X ) );
kevman 0:38ceb79fef03 81
kevman 0:38ceb79fef03 82 cleanup:
kevman 0:38ceb79fef03 83 mbedtls_ecp_point_free( &P );
kevman 0:38ceb79fef03 84
kevman 0:38ceb79fef03 85 return( ret );
kevman 0:38ceb79fef03 86 }
kevman 0:38ceb79fef03 87 #endif /* MBEDTLS_ECDH_COMPUTE_SHARED_ALT */
kevman 0:38ceb79fef03 88
kevman 0:38ceb79fef03 89 /*
kevman 0:38ceb79fef03 90 * Initialize context
kevman 0:38ceb79fef03 91 */
kevman 0:38ceb79fef03 92 void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx )
kevman 0:38ceb79fef03 93 {
kevman 0:38ceb79fef03 94 memset( ctx, 0, sizeof( mbedtls_ecdh_context ) );
kevman 0:38ceb79fef03 95 }
kevman 0:38ceb79fef03 96
kevman 0:38ceb79fef03 97 /*
kevman 0:38ceb79fef03 98 * Free context
kevman 0:38ceb79fef03 99 */
kevman 0:38ceb79fef03 100 void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx )
kevman 0:38ceb79fef03 101 {
kevman 0:38ceb79fef03 102 if( ctx == NULL )
kevman 0:38ceb79fef03 103 return;
kevman 0:38ceb79fef03 104
kevman 0:38ceb79fef03 105 mbedtls_ecp_group_free( &ctx->grp );
kevman 0:38ceb79fef03 106 mbedtls_ecp_point_free( &ctx->Q );
kevman 0:38ceb79fef03 107 mbedtls_ecp_point_free( &ctx->Qp );
kevman 0:38ceb79fef03 108 mbedtls_ecp_point_free( &ctx->Vi );
kevman 0:38ceb79fef03 109 mbedtls_ecp_point_free( &ctx->Vf );
kevman 0:38ceb79fef03 110 mbedtls_mpi_free( &ctx->d );
kevman 0:38ceb79fef03 111 mbedtls_mpi_free( &ctx->z );
kevman 0:38ceb79fef03 112 mbedtls_mpi_free( &ctx->_d );
kevman 0:38ceb79fef03 113 }
kevman 0:38ceb79fef03 114
kevman 0:38ceb79fef03 115 /*
kevman 0:38ceb79fef03 116 * Setup and write the ServerKeyExhange parameters (RFC 4492)
kevman 0:38ceb79fef03 117 * struct {
kevman 0:38ceb79fef03 118 * ECParameters curve_params;
kevman 0:38ceb79fef03 119 * ECPoint public;
kevman 0:38ceb79fef03 120 * } ServerECDHParams;
kevman 0:38ceb79fef03 121 */
kevman 0:38ceb79fef03 122 int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
kevman 0:38ceb79fef03 123 unsigned char *buf, size_t blen,
kevman 0:38ceb79fef03 124 int (*f_rng)(void *, unsigned char *, size_t),
kevman 0:38ceb79fef03 125 void *p_rng )
kevman 0:38ceb79fef03 126 {
kevman 0:38ceb79fef03 127 int ret;
kevman 0:38ceb79fef03 128 size_t grp_len, pt_len;
kevman 0:38ceb79fef03 129
kevman 0:38ceb79fef03 130 if( ctx == NULL || ctx->grp.pbits == 0 )
kevman 0:38ceb79fef03 131 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
kevman 0:38ceb79fef03 132
kevman 0:38ceb79fef03 133 if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
kevman 0:38ceb79fef03 134 != 0 )
kevman 0:38ceb79fef03 135 return( ret );
kevman 0:38ceb79fef03 136
kevman 0:38ceb79fef03 137 if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf, blen ) )
kevman 0:38ceb79fef03 138 != 0 )
kevman 0:38ceb79fef03 139 return( ret );
kevman 0:38ceb79fef03 140
kevman 0:38ceb79fef03 141 buf += grp_len;
kevman 0:38ceb79fef03 142 blen -= grp_len;
kevman 0:38ceb79fef03 143
kevman 0:38ceb79fef03 144 if( ( ret = mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
kevman 0:38ceb79fef03 145 &pt_len, buf, blen ) ) != 0 )
kevman 0:38ceb79fef03 146 return( ret );
kevman 0:38ceb79fef03 147
kevman 0:38ceb79fef03 148 *olen = grp_len + pt_len;
kevman 0:38ceb79fef03 149 return( 0 );
kevman 0:38ceb79fef03 150 }
kevman 0:38ceb79fef03 151
kevman 0:38ceb79fef03 152 /*
kevman 0:38ceb79fef03 153 * Read the ServerKeyExhange parameters (RFC 4492)
kevman 0:38ceb79fef03 154 * struct {
kevman 0:38ceb79fef03 155 * ECParameters curve_params;
kevman 0:38ceb79fef03 156 * ECPoint public;
kevman 0:38ceb79fef03 157 * } ServerECDHParams;
kevman 0:38ceb79fef03 158 */
kevman 0:38ceb79fef03 159 int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
kevman 0:38ceb79fef03 160 const unsigned char **buf, const unsigned char *end )
kevman 0:38ceb79fef03 161 {
kevman 0:38ceb79fef03 162 int ret;
kevman 0:38ceb79fef03 163
kevman 0:38ceb79fef03 164 if( ( ret = mbedtls_ecp_tls_read_group( &ctx->grp, buf, end - *buf ) ) != 0 )
kevman 0:38ceb79fef03 165 return( ret );
kevman 0:38ceb79fef03 166
kevman 0:38ceb79fef03 167 if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf, end - *buf ) )
kevman 0:38ceb79fef03 168 != 0 )
kevman 0:38ceb79fef03 169 return( ret );
kevman 0:38ceb79fef03 170
kevman 0:38ceb79fef03 171 return( 0 );
kevman 0:38ceb79fef03 172 }
kevman 0:38ceb79fef03 173
kevman 0:38ceb79fef03 174 /*
kevman 0:38ceb79fef03 175 * Get parameters from a keypair
kevman 0:38ceb79fef03 176 */
kevman 0:38ceb79fef03 177 int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key,
kevman 0:38ceb79fef03 178 mbedtls_ecdh_side side )
kevman 0:38ceb79fef03 179 {
kevman 0:38ceb79fef03 180 int ret;
kevman 0:38ceb79fef03 181
kevman 0:38ceb79fef03 182 if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 )
kevman 0:38ceb79fef03 183 return( ret );
kevman 0:38ceb79fef03 184
kevman 0:38ceb79fef03 185 /* If it's not our key, just import the public part as Qp */
kevman 0:38ceb79fef03 186 if( side == MBEDTLS_ECDH_THEIRS )
kevman 0:38ceb79fef03 187 return( mbedtls_ecp_copy( &ctx->Qp, &key->Q ) );
kevman 0:38ceb79fef03 188
kevman 0:38ceb79fef03 189 /* Our key: import public (as Q) and private parts */
kevman 0:38ceb79fef03 190 if( side != MBEDTLS_ECDH_OURS )
kevman 0:38ceb79fef03 191 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
kevman 0:38ceb79fef03 192
kevman 0:38ceb79fef03 193 if( ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 ||
kevman 0:38ceb79fef03 194 ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 )
kevman 0:38ceb79fef03 195 return( ret );
kevman 0:38ceb79fef03 196
kevman 0:38ceb79fef03 197 return( 0 );
kevman 0:38ceb79fef03 198 }
kevman 0:38ceb79fef03 199
kevman 0:38ceb79fef03 200 /*
kevman 0:38ceb79fef03 201 * Setup and export the client public value
kevman 0:38ceb79fef03 202 */
kevman 0:38ceb79fef03 203 int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
kevman 0:38ceb79fef03 204 unsigned char *buf, size_t blen,
kevman 0:38ceb79fef03 205 int (*f_rng)(void *, unsigned char *, size_t),
kevman 0:38ceb79fef03 206 void *p_rng )
kevman 0:38ceb79fef03 207 {
kevman 0:38ceb79fef03 208 int ret;
kevman 0:38ceb79fef03 209
kevman 0:38ceb79fef03 210 if( ctx == NULL || ctx->grp.pbits == 0 )
kevman 0:38ceb79fef03 211 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
kevman 0:38ceb79fef03 212
kevman 0:38ceb79fef03 213 if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
kevman 0:38ceb79fef03 214 != 0 )
kevman 0:38ceb79fef03 215 return( ret );
kevman 0:38ceb79fef03 216
kevman 0:38ceb79fef03 217 return mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
kevman 0:38ceb79fef03 218 olen, buf, blen );
kevman 0:38ceb79fef03 219 }
kevman 0:38ceb79fef03 220
kevman 0:38ceb79fef03 221 /*
kevman 0:38ceb79fef03 222 * Parse and import the client's public value
kevman 0:38ceb79fef03 223 */
kevman 0:38ceb79fef03 224 int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
kevman 0:38ceb79fef03 225 const unsigned char *buf, size_t blen )
kevman 0:38ceb79fef03 226 {
kevman 0:38ceb79fef03 227 int ret;
kevman 0:38ceb79fef03 228 const unsigned char *p = buf;
kevman 0:38ceb79fef03 229
kevman 0:38ceb79fef03 230 if( ctx == NULL )
kevman 0:38ceb79fef03 231 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
kevman 0:38ceb79fef03 232
kevman 0:38ceb79fef03 233 if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, &p, blen ) ) != 0 )
kevman 0:38ceb79fef03 234 return( ret );
kevman 0:38ceb79fef03 235
kevman 0:38ceb79fef03 236 if( (size_t)( p - buf ) != blen )
kevman 0:38ceb79fef03 237 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
kevman 0:38ceb79fef03 238
kevman 0:38ceb79fef03 239 return( 0 );
kevman 0:38ceb79fef03 240 }
kevman 0:38ceb79fef03 241
kevman 0:38ceb79fef03 242 /*
kevman 0:38ceb79fef03 243 * Derive and export the shared secret
kevman 0:38ceb79fef03 244 */
kevman 0:38ceb79fef03 245 int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
kevman 0:38ceb79fef03 246 unsigned char *buf, size_t blen,
kevman 0:38ceb79fef03 247 int (*f_rng)(void *, unsigned char *, size_t),
kevman 0:38ceb79fef03 248 void *p_rng )
kevman 0:38ceb79fef03 249 {
kevman 0:38ceb79fef03 250 int ret;
kevman 0:38ceb79fef03 251
kevman 0:38ceb79fef03 252 if( ctx == NULL )
kevman 0:38ceb79fef03 253 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
kevman 0:38ceb79fef03 254
kevman 0:38ceb79fef03 255 if( ( ret = mbedtls_ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp, &ctx->d,
kevman 0:38ceb79fef03 256 f_rng, p_rng ) ) != 0 )
kevman 0:38ceb79fef03 257 {
kevman 0:38ceb79fef03 258 return( ret );
kevman 0:38ceb79fef03 259 }
kevman 0:38ceb79fef03 260
kevman 0:38ceb79fef03 261 if( mbedtls_mpi_size( &ctx->z ) > blen )
kevman 0:38ceb79fef03 262 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
kevman 0:38ceb79fef03 263
kevman 0:38ceb79fef03 264 *olen = ctx->grp.pbits / 8 + ( ( ctx->grp.pbits % 8 ) != 0 );
kevman 0:38ceb79fef03 265 return mbedtls_mpi_write_binary( &ctx->z, buf, *olen );
kevman 0:38ceb79fef03 266 }
kevman 0:38ceb79fef03 267
kevman 0:38ceb79fef03 268 #endif /* MBEDTLS_ECDH_C */