Rahul Dahiya / Mbed OS STM32F7 Ethernet

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mbed-os/features/mbedtls/src/ecdh.c@0:fb8047b156bb, 2020-01-15 (annotated)

Committer:
rahul_dahiya
Date:
Wed Jan 15 15:57:15 2020 +0530
Revision:
0:fb8047b156bb
STM32F7 LWIP

Who changed what in which revision?

UserRevisionLine numberNew contents of line
rahul_dahiya 0:fb8047b156bb 1 /*
rahul_dahiya 0:fb8047b156bb 2 * Elliptic curve Diffie-Hellman
rahul_dahiya 0:fb8047b156bb 3 *
rahul_dahiya 0:fb8047b156bb 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
rahul_dahiya 0:fb8047b156bb 5 * SPDX-License-Identifier: Apache-2.0
rahul_dahiya 0:fb8047b156bb 6 *
rahul_dahiya 0:fb8047b156bb 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
rahul_dahiya 0:fb8047b156bb 8 * not use this file except in compliance with the License.
rahul_dahiya 0:fb8047b156bb 9 * You may obtain a copy of the License at
rahul_dahiya 0:fb8047b156bb 10 *
rahul_dahiya 0:fb8047b156bb 11 * http://www.apache.org/licenses/LICENSE-2.0
rahul_dahiya 0:fb8047b156bb 12 *
rahul_dahiya 0:fb8047b156bb 13 * Unless required by applicable law or agreed to in writing, software
rahul_dahiya 0:fb8047b156bb 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
rahul_dahiya 0:fb8047b156bb 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
rahul_dahiya 0:fb8047b156bb 16 * See the License for the specific language governing permissions and
rahul_dahiya 0:fb8047b156bb 17 * limitations under the License.
rahul_dahiya 0:fb8047b156bb 18 *
rahul_dahiya 0:fb8047b156bb 19 * This file is part of mbed TLS (https://tls.mbed.org)
rahul_dahiya 0:fb8047b156bb 20 */
rahul_dahiya 0:fb8047b156bb 21
rahul_dahiya 0:fb8047b156bb 22 /*
rahul_dahiya 0:fb8047b156bb 23 * References:
rahul_dahiya 0:fb8047b156bb 24 *
rahul_dahiya 0:fb8047b156bb 25 * SEC1 http://www.secg.org/index.php?action=secg,docs_secg
rahul_dahiya 0:fb8047b156bb 26 * RFC 4492
rahul_dahiya 0:fb8047b156bb 27 */
rahul_dahiya 0:fb8047b156bb 28
rahul_dahiya 0:fb8047b156bb 29 #if !defined(MBEDTLS_CONFIG_FILE)
rahul_dahiya 0:fb8047b156bb 30 #include "mbedtls/config.h"
rahul_dahiya 0:fb8047b156bb 31 #else
rahul_dahiya 0:fb8047b156bb 32 #include MBEDTLS_CONFIG_FILE
rahul_dahiya 0:fb8047b156bb 33 #endif
rahul_dahiya 0:fb8047b156bb 34
rahul_dahiya 0:fb8047b156bb 35 #if defined(MBEDTLS_ECDH_C)
rahul_dahiya 0:fb8047b156bb 36
rahul_dahiya 0:fb8047b156bb 37 #include "mbedtls/ecdh.h"
rahul_dahiya 0:fb8047b156bb 38
rahul_dahiya 0:fb8047b156bb 39 #include <string.h>
rahul_dahiya 0:fb8047b156bb 40
rahul_dahiya 0:fb8047b156bb 41 /*
rahul_dahiya 0:fb8047b156bb 42 * Generate public key: simple wrapper around mbedtls_ecp_gen_keypair
rahul_dahiya 0:fb8047b156bb 43 */
rahul_dahiya 0:fb8047b156bb 44 int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q,
rahul_dahiya 0:fb8047b156bb 45 int (*f_rng)(void *, unsigned char *, size_t),
rahul_dahiya 0:fb8047b156bb 46 void *p_rng )
rahul_dahiya 0:fb8047b156bb 47 {
rahul_dahiya 0:fb8047b156bb 48 return mbedtls_ecp_gen_keypair( grp, d, Q, f_rng, p_rng );
rahul_dahiya 0:fb8047b156bb 49 }
rahul_dahiya 0:fb8047b156bb 50
rahul_dahiya 0:fb8047b156bb 51 /*
rahul_dahiya 0:fb8047b156bb 52 * Compute shared secret (SEC1 3.3.1)
rahul_dahiya 0:fb8047b156bb 53 */
rahul_dahiya 0:fb8047b156bb 54 int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
rahul_dahiya 0:fb8047b156bb 55 const mbedtls_ecp_point *Q, const mbedtls_mpi *d,
rahul_dahiya 0:fb8047b156bb 56 int (*f_rng)(void *, unsigned char *, size_t),
rahul_dahiya 0:fb8047b156bb 57 void *p_rng )
rahul_dahiya 0:fb8047b156bb 58 {
rahul_dahiya 0:fb8047b156bb 59 int ret;
rahul_dahiya 0:fb8047b156bb 60 mbedtls_ecp_point P;
rahul_dahiya 0:fb8047b156bb 61
rahul_dahiya 0:fb8047b156bb 62 mbedtls_ecp_point_init( &P );
rahul_dahiya 0:fb8047b156bb 63
rahul_dahiya 0:fb8047b156bb 64 /*
rahul_dahiya 0:fb8047b156bb 65 * Make sure Q is a valid pubkey before using it
rahul_dahiya 0:fb8047b156bb 66 */
rahul_dahiya 0:fb8047b156bb 67 MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
rahul_dahiya 0:fb8047b156bb 68
rahul_dahiya 0:fb8047b156bb 69 MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, &P, d, Q, f_rng, p_rng ) );
rahul_dahiya 0:fb8047b156bb 70
rahul_dahiya 0:fb8047b156bb 71 if( mbedtls_ecp_is_zero( &P ) )
rahul_dahiya 0:fb8047b156bb 72 {
rahul_dahiya 0:fb8047b156bb 73 ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
rahul_dahiya 0:fb8047b156bb 74 goto cleanup;
rahul_dahiya 0:fb8047b156bb 75 }
rahul_dahiya 0:fb8047b156bb 76
rahul_dahiya 0:fb8047b156bb 77 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( z, &P.X ) );
rahul_dahiya 0:fb8047b156bb 78
rahul_dahiya 0:fb8047b156bb 79 cleanup:
rahul_dahiya 0:fb8047b156bb 80 mbedtls_ecp_point_free( &P );
rahul_dahiya 0:fb8047b156bb 81
rahul_dahiya 0:fb8047b156bb 82 return( ret );
rahul_dahiya 0:fb8047b156bb 83 }
rahul_dahiya 0:fb8047b156bb 84
rahul_dahiya 0:fb8047b156bb 85 /*
rahul_dahiya 0:fb8047b156bb 86 * Initialize context
rahul_dahiya 0:fb8047b156bb 87 */
rahul_dahiya 0:fb8047b156bb 88 void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx )
rahul_dahiya 0:fb8047b156bb 89 {
rahul_dahiya 0:fb8047b156bb 90 memset( ctx, 0, sizeof( mbedtls_ecdh_context ) );
rahul_dahiya 0:fb8047b156bb 91 }
rahul_dahiya 0:fb8047b156bb 92
rahul_dahiya 0:fb8047b156bb 93 /*
rahul_dahiya 0:fb8047b156bb 94 * Free context
rahul_dahiya 0:fb8047b156bb 95 */
rahul_dahiya 0:fb8047b156bb 96 void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx )
rahul_dahiya 0:fb8047b156bb 97 {
rahul_dahiya 0:fb8047b156bb 98 if( ctx == NULL )
rahul_dahiya 0:fb8047b156bb 99 return;
rahul_dahiya 0:fb8047b156bb 100
rahul_dahiya 0:fb8047b156bb 101 mbedtls_ecp_group_free( &ctx->grp );
rahul_dahiya 0:fb8047b156bb 102 mbedtls_ecp_point_free( &ctx->Q );
rahul_dahiya 0:fb8047b156bb 103 mbedtls_ecp_point_free( &ctx->Qp );
rahul_dahiya 0:fb8047b156bb 104 mbedtls_ecp_point_free( &ctx->Vi );
rahul_dahiya 0:fb8047b156bb 105 mbedtls_ecp_point_free( &ctx->Vf );
rahul_dahiya 0:fb8047b156bb 106 mbedtls_mpi_free( &ctx->d );
rahul_dahiya 0:fb8047b156bb 107 mbedtls_mpi_free( &ctx->z );
rahul_dahiya 0:fb8047b156bb 108 mbedtls_mpi_free( &ctx->_d );
rahul_dahiya 0:fb8047b156bb 109 }
rahul_dahiya 0:fb8047b156bb 110
rahul_dahiya 0:fb8047b156bb 111 /*
rahul_dahiya 0:fb8047b156bb 112 * Setup and write the ServerKeyExhange parameters (RFC 4492)
rahul_dahiya 0:fb8047b156bb 113 * struct {
rahul_dahiya 0:fb8047b156bb 114 * ECParameters curve_params;
rahul_dahiya 0:fb8047b156bb 115 * ECPoint public;
rahul_dahiya 0:fb8047b156bb 116 * } ServerECDHParams;
rahul_dahiya 0:fb8047b156bb 117 */
rahul_dahiya 0:fb8047b156bb 118 int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
rahul_dahiya 0:fb8047b156bb 119 unsigned char *buf, size_t blen,
rahul_dahiya 0:fb8047b156bb 120 int (*f_rng)(void *, unsigned char *, size_t),
rahul_dahiya 0:fb8047b156bb 121 void *p_rng )
rahul_dahiya 0:fb8047b156bb 122 {
rahul_dahiya 0:fb8047b156bb 123 int ret;
rahul_dahiya 0:fb8047b156bb 124 size_t grp_len, pt_len;
rahul_dahiya 0:fb8047b156bb 125
rahul_dahiya 0:fb8047b156bb 126 if( ctx == NULL || ctx->grp.pbits == 0 )
rahul_dahiya 0:fb8047b156bb 127 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
rahul_dahiya 0:fb8047b156bb 128
rahul_dahiya 0:fb8047b156bb 129 if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
rahul_dahiya 0:fb8047b156bb 130 != 0 )
rahul_dahiya 0:fb8047b156bb 131 return( ret );
rahul_dahiya 0:fb8047b156bb 132
rahul_dahiya 0:fb8047b156bb 133 if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf, blen ) )
rahul_dahiya 0:fb8047b156bb 134 != 0 )
rahul_dahiya 0:fb8047b156bb 135 return( ret );
rahul_dahiya 0:fb8047b156bb 136
rahul_dahiya 0:fb8047b156bb 137 buf += grp_len;
rahul_dahiya 0:fb8047b156bb 138 blen -= grp_len;
rahul_dahiya 0:fb8047b156bb 139
rahul_dahiya 0:fb8047b156bb 140 if( ( ret = mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
rahul_dahiya 0:fb8047b156bb 141 &pt_len, buf, blen ) ) != 0 )
rahul_dahiya 0:fb8047b156bb 142 return( ret );
rahul_dahiya 0:fb8047b156bb 143
rahul_dahiya 0:fb8047b156bb 144 *olen = grp_len + pt_len;
rahul_dahiya 0:fb8047b156bb 145 return( 0 );
rahul_dahiya 0:fb8047b156bb 146 }
rahul_dahiya 0:fb8047b156bb 147
rahul_dahiya 0:fb8047b156bb 148 /*
rahul_dahiya 0:fb8047b156bb 149 * Read the ServerKeyExhange parameters (RFC 4492)
rahul_dahiya 0:fb8047b156bb 150 * struct {
rahul_dahiya 0:fb8047b156bb 151 * ECParameters curve_params;
rahul_dahiya 0:fb8047b156bb 152 * ECPoint public;
rahul_dahiya 0:fb8047b156bb 153 * } ServerECDHParams;
rahul_dahiya 0:fb8047b156bb 154 */
rahul_dahiya 0:fb8047b156bb 155 int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
rahul_dahiya 0:fb8047b156bb 156 const unsigned char **buf, const unsigned char *end )
rahul_dahiya 0:fb8047b156bb 157 {
rahul_dahiya 0:fb8047b156bb 158 int ret;
rahul_dahiya 0:fb8047b156bb 159
rahul_dahiya 0:fb8047b156bb 160 if( ( ret = mbedtls_ecp_tls_read_group( &ctx->grp, buf, end - *buf ) ) != 0 )
rahul_dahiya 0:fb8047b156bb 161 return( ret );
rahul_dahiya 0:fb8047b156bb 162
rahul_dahiya 0:fb8047b156bb 163 if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf, end - *buf ) )
rahul_dahiya 0:fb8047b156bb 164 != 0 )
rahul_dahiya 0:fb8047b156bb 165 return( ret );
rahul_dahiya 0:fb8047b156bb 166
rahul_dahiya 0:fb8047b156bb 167 return( 0 );
rahul_dahiya 0:fb8047b156bb 168 }
rahul_dahiya 0:fb8047b156bb 169
rahul_dahiya 0:fb8047b156bb 170 /*
rahul_dahiya 0:fb8047b156bb 171 * Get parameters from a keypair
rahul_dahiya 0:fb8047b156bb 172 */
rahul_dahiya 0:fb8047b156bb 173 int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key,
rahul_dahiya 0:fb8047b156bb 174 mbedtls_ecdh_side side )
rahul_dahiya 0:fb8047b156bb 175 {
rahul_dahiya 0:fb8047b156bb 176 int ret;
rahul_dahiya 0:fb8047b156bb 177
rahul_dahiya 0:fb8047b156bb 178 if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 )
rahul_dahiya 0:fb8047b156bb 179 return( ret );
rahul_dahiya 0:fb8047b156bb 180
rahul_dahiya 0:fb8047b156bb 181 /* If it's not our key, just import the public part as Qp */
rahul_dahiya 0:fb8047b156bb 182 if( side == MBEDTLS_ECDH_THEIRS )
rahul_dahiya 0:fb8047b156bb 183 return( mbedtls_ecp_copy( &ctx->Qp, &key->Q ) );
rahul_dahiya 0:fb8047b156bb 184
rahul_dahiya 0:fb8047b156bb 185 /* Our key: import public (as Q) and private parts */
rahul_dahiya 0:fb8047b156bb 186 if( side != MBEDTLS_ECDH_OURS )
rahul_dahiya 0:fb8047b156bb 187 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
rahul_dahiya 0:fb8047b156bb 188
rahul_dahiya 0:fb8047b156bb 189 if( ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 ||
rahul_dahiya 0:fb8047b156bb 190 ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 )
rahul_dahiya 0:fb8047b156bb 191 return( ret );
rahul_dahiya 0:fb8047b156bb 192
rahul_dahiya 0:fb8047b156bb 193 return( 0 );
rahul_dahiya 0:fb8047b156bb 194 }
rahul_dahiya 0:fb8047b156bb 195
rahul_dahiya 0:fb8047b156bb 196 /*
rahul_dahiya 0:fb8047b156bb 197 * Setup and export the client public value
rahul_dahiya 0:fb8047b156bb 198 */
rahul_dahiya 0:fb8047b156bb 199 int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
rahul_dahiya 0:fb8047b156bb 200 unsigned char *buf, size_t blen,
rahul_dahiya 0:fb8047b156bb 201 int (*f_rng)(void *, unsigned char *, size_t),
rahul_dahiya 0:fb8047b156bb 202 void *p_rng )
rahul_dahiya 0:fb8047b156bb 203 {
rahul_dahiya 0:fb8047b156bb 204 int ret;
rahul_dahiya 0:fb8047b156bb 205
rahul_dahiya 0:fb8047b156bb 206 if( ctx == NULL || ctx->grp.pbits == 0 )
rahul_dahiya 0:fb8047b156bb 207 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
rahul_dahiya 0:fb8047b156bb 208
rahul_dahiya 0:fb8047b156bb 209 if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
rahul_dahiya 0:fb8047b156bb 210 != 0 )
rahul_dahiya 0:fb8047b156bb 211 return( ret );
rahul_dahiya 0:fb8047b156bb 212
rahul_dahiya 0:fb8047b156bb 213 return mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
rahul_dahiya 0:fb8047b156bb 214 olen, buf, blen );
rahul_dahiya 0:fb8047b156bb 215 }
rahul_dahiya 0:fb8047b156bb 216
rahul_dahiya 0:fb8047b156bb 217 /*
rahul_dahiya 0:fb8047b156bb 218 * Parse and import the client's public value
rahul_dahiya 0:fb8047b156bb 219 */
rahul_dahiya 0:fb8047b156bb 220 int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
rahul_dahiya 0:fb8047b156bb 221 const unsigned char *buf, size_t blen )
rahul_dahiya 0:fb8047b156bb 222 {
rahul_dahiya 0:fb8047b156bb 223 int ret;
rahul_dahiya 0:fb8047b156bb 224 const unsigned char *p = buf;
rahul_dahiya 0:fb8047b156bb 225
rahul_dahiya 0:fb8047b156bb 226 if( ctx == NULL )
rahul_dahiya 0:fb8047b156bb 227 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
rahul_dahiya 0:fb8047b156bb 228
rahul_dahiya 0:fb8047b156bb 229 if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, &p, blen ) ) != 0 )
rahul_dahiya 0:fb8047b156bb 230 return( ret );
rahul_dahiya 0:fb8047b156bb 231
rahul_dahiya 0:fb8047b156bb 232 if( (size_t)( p - buf ) != blen )
rahul_dahiya 0:fb8047b156bb 233 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
rahul_dahiya 0:fb8047b156bb 234
rahul_dahiya 0:fb8047b156bb 235 return( 0 );
rahul_dahiya 0:fb8047b156bb 236 }
rahul_dahiya 0:fb8047b156bb 237
rahul_dahiya 0:fb8047b156bb 238 /*
rahul_dahiya 0:fb8047b156bb 239 * Derive and export the shared secret
rahul_dahiya 0:fb8047b156bb 240 */
rahul_dahiya 0:fb8047b156bb 241 int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
rahul_dahiya 0:fb8047b156bb 242 unsigned char *buf, size_t blen,
rahul_dahiya 0:fb8047b156bb 243 int (*f_rng)(void *, unsigned char *, size_t),
rahul_dahiya 0:fb8047b156bb 244 void *p_rng )
rahul_dahiya 0:fb8047b156bb 245 {
rahul_dahiya 0:fb8047b156bb 246 int ret;
rahul_dahiya 0:fb8047b156bb 247
rahul_dahiya 0:fb8047b156bb 248 if( ctx == NULL )
rahul_dahiya 0:fb8047b156bb 249 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
rahul_dahiya 0:fb8047b156bb 250
rahul_dahiya 0:fb8047b156bb 251 if( ( ret = mbedtls_ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp, &ctx->d,
rahul_dahiya 0:fb8047b156bb 252 f_rng, p_rng ) ) != 0 )
rahul_dahiya 0:fb8047b156bb 253 {
rahul_dahiya 0:fb8047b156bb 254 return( ret );
rahul_dahiya 0:fb8047b156bb 255 }
rahul_dahiya 0:fb8047b156bb 256
rahul_dahiya 0:fb8047b156bb 257 if( mbedtls_mpi_size( &ctx->z ) > blen )
rahul_dahiya 0:fb8047b156bb 258 return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
rahul_dahiya 0:fb8047b156bb 259
rahul_dahiya 0:fb8047b156bb 260 *olen = ctx->grp.pbits / 8 + ( ( ctx->grp.pbits % 8 ) != 0 );
rahul_dahiya 0:fb8047b156bb 261 return mbedtls_mpi_write_binary( &ctx->z, buf, *olen );
rahul_dahiya 0:fb8047b156bb 262 }
rahul_dahiya 0:fb8047b156bb 263
rahul_dahiya 0:fb8047b156bb 264 #endif /* MBEDTLS_ECDH_C */