Nitin Shukla / LED_Demo

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Dependencies:   MAX44000 nexpaq_mdk

Fork of LED_Demo by Maxim nexpaq

mbd_os/features/mbedtls/src/dhm.c@7:3a65ef12ba31, 2016-11-04 (annotated)

Committer:
nitsshukla
Date:
Fri Nov 04 12:06:04 2016 +0000
Revision:
7:3a65ef12ba31
Parent:
1:55a6170b404f 
kghj;

Who changed what in which revision?

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nexpaq 1:55a6170b404f 1 /*
nexpaq 1:55a6170b404f 2 * Diffie-Hellman-Merkle key exchange
nexpaq 1:55a6170b404f 3 *
nexpaq 1:55a6170b404f 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
nexpaq 1:55a6170b404f 5 * SPDX-License-Identifier: Apache-2.0
nexpaq 1:55a6170b404f 6 *
nexpaq 1:55a6170b404f 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
nexpaq 1:55a6170b404f 8 * not use this file except in compliance with the License.
nexpaq 1:55a6170b404f 9 * You may obtain a copy of the License at
nexpaq 1:55a6170b404f 10 *
nexpaq 1:55a6170b404f 11 * http://www.apache.org/licenses/LICENSE-2.0
nexpaq 1:55a6170b404f 12 *
nexpaq 1:55a6170b404f 13 * Unless required by applicable law or agreed to in writing, software
nexpaq 1:55a6170b404f 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
nexpaq 1:55a6170b404f 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
nexpaq 1:55a6170b404f 16 * See the License for the specific language governing permissions and
nexpaq 1:55a6170b404f 17 * limitations under the License.
nexpaq 1:55a6170b404f 18 *
nexpaq 1:55a6170b404f 19 * This file is part of mbed TLS (https://tls.mbed.org)
nexpaq 1:55a6170b404f 20 */
nexpaq 1:55a6170b404f 21 /*
nexpaq 1:55a6170b404f 22 * The following sources were referenced in the design of this implementation
nexpaq 1:55a6170b404f 23 * of the Diffie-Hellman-Merkle algorithm:
nexpaq 1:55a6170b404f 24 *
nexpaq 1:55a6170b404f 25 * [1] Handbook of Applied Cryptography - 1997, Chapter 12
nexpaq 1:55a6170b404f 26 * Menezes, van Oorschot and Vanstone
nexpaq 1:55a6170b404f 27 *
nexpaq 1:55a6170b404f 28 */
nexpaq 1:55a6170b404f 29
nexpaq 1:55a6170b404f 30 #if !defined(MBEDTLS_CONFIG_FILE)
nexpaq 1:55a6170b404f 31 #include "mbedtls/config.h"
nexpaq 1:55a6170b404f 32 #else
nexpaq 1:55a6170b404f 33 #include MBEDTLS_CONFIG_FILE
nexpaq 1:55a6170b404f 34 #endif
nexpaq 1:55a6170b404f 35
nexpaq 1:55a6170b404f 36 #if defined(MBEDTLS_DHM_C)
nexpaq 1:55a6170b404f 37
nexpaq 1:55a6170b404f 38 #include "mbedtls/dhm.h"
nexpaq 1:55a6170b404f 39
nexpaq 1:55a6170b404f 40 #include <string.h>
nexpaq 1:55a6170b404f 41
nexpaq 1:55a6170b404f 42 #if defined(MBEDTLS_PEM_PARSE_C)
nexpaq 1:55a6170b404f 43 #include "mbedtls/pem.h"
nexpaq 1:55a6170b404f 44 #endif
nexpaq 1:55a6170b404f 45
nexpaq 1:55a6170b404f 46 #if defined(MBEDTLS_ASN1_PARSE_C)
nexpaq 1:55a6170b404f 47 #include "mbedtls/asn1.h"
nexpaq 1:55a6170b404f 48 #endif
nexpaq 1:55a6170b404f 49
nexpaq 1:55a6170b404f 50 #if defined(MBEDTLS_PLATFORM_C)
nexpaq 1:55a6170b404f 51 #include "mbedtls/platform.h"
nexpaq 1:55a6170b404f 52 #else
nexpaq 1:55a6170b404f 53 #include <stdlib.h>
nexpaq 1:55a6170b404f 54 #include <stdio.h>
nexpaq 1:55a6170b404f 55 #define mbedtls_printf printf
nexpaq 1:55a6170b404f 56 #define mbedtls_calloc calloc
nexpaq 1:55a6170b404f 57 #define mbedtls_free free
nexpaq 1:55a6170b404f 58 #endif
nexpaq 1:55a6170b404f 59
nexpaq 1:55a6170b404f 60 /* Implementation that should never be optimized out by the compiler */
nexpaq 1:55a6170b404f 61 static void mbedtls_zeroize( void *v, size_t n ) {
nexpaq 1:55a6170b404f 62 volatile unsigned char *p = v; while( n-- ) *p++ = 0;
nexpaq 1:55a6170b404f 63 }
nexpaq 1:55a6170b404f 64
nexpaq 1:55a6170b404f 65 /*
nexpaq 1:55a6170b404f 66 * helper to validate the mbedtls_mpi size and import it
nexpaq 1:55a6170b404f 67 */
nexpaq 1:55a6170b404f 68 static int dhm_read_bignum( mbedtls_mpi *X,
nexpaq 1:55a6170b404f 69 unsigned char **p,
nexpaq 1:55a6170b404f 70 const unsigned char *end )
nexpaq 1:55a6170b404f 71 {
nexpaq 1:55a6170b404f 72 int ret, n;
nexpaq 1:55a6170b404f 73
nexpaq 1:55a6170b404f 74 if( end - *p < 2 )
nexpaq 1:55a6170b404f 75 return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
nexpaq 1:55a6170b404f 76
nexpaq 1:55a6170b404f 77 n = ( (*p)[0] << 8 ) | (*p)[1];
nexpaq 1:55a6170b404f 78 (*p) += 2;
nexpaq 1:55a6170b404f 79
nexpaq 1:55a6170b404f 80 if( (int)( end - *p ) < n )
nexpaq 1:55a6170b404f 81 return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
nexpaq 1:55a6170b404f 82
nexpaq 1:55a6170b404f 83 if( ( ret = mbedtls_mpi_read_binary( X, *p, n ) ) != 0 )
nexpaq 1:55a6170b404f 84 return( MBEDTLS_ERR_DHM_READ_PARAMS_FAILED + ret );
nexpaq 1:55a6170b404f 85
nexpaq 1:55a6170b404f 86 (*p) += n;
nexpaq 1:55a6170b404f 87
nexpaq 1:55a6170b404f 88 return( 0 );
nexpaq 1:55a6170b404f 89 }
nexpaq 1:55a6170b404f 90
nexpaq 1:55a6170b404f 91 /*
nexpaq 1:55a6170b404f 92 * Verify sanity of parameter with regards to P
nexpaq 1:55a6170b404f 93 *
nexpaq 1:55a6170b404f 94 * Parameter should be: 2 <= public_param <= P - 2
nexpaq 1:55a6170b404f 95 *
nexpaq 1:55a6170b404f 96 * For more information on the attack, see:
nexpaq 1:55a6170b404f 97 * http://www.cl.cam.ac.uk/~rja14/Papers/psandqs.pdf
nexpaq 1:55a6170b404f 98 * http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2005-2643
nexpaq 1:55a6170b404f 99 */
nexpaq 1:55a6170b404f 100 static int dhm_check_range( const mbedtls_mpi *param, const mbedtls_mpi *P )
nexpaq 1:55a6170b404f 101 {
nexpaq 1:55a6170b404f 102 mbedtls_mpi L, U;
nexpaq 1:55a6170b404f 103 int ret = MBEDTLS_ERR_DHM_BAD_INPUT_DATA;
nexpaq 1:55a6170b404f 104
nexpaq 1:55a6170b404f 105 mbedtls_mpi_init( &L ); mbedtls_mpi_init( &U );
nexpaq 1:55a6170b404f 106
nexpaq 1:55a6170b404f 107 MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &L, 2 ) );
nexpaq 1:55a6170b404f 108 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &U, P, 2 ) );
nexpaq 1:55a6170b404f 109
nexpaq 1:55a6170b404f 110 if( mbedtls_mpi_cmp_mpi( param, &L ) >= 0 &&
nexpaq 1:55a6170b404f 111 mbedtls_mpi_cmp_mpi( param, &U ) <= 0 )
nexpaq 1:55a6170b404f 112 {
nexpaq 1:55a6170b404f 113 ret = 0;
nexpaq 1:55a6170b404f 114 }
nexpaq 1:55a6170b404f 115
nexpaq 1:55a6170b404f 116 cleanup:
nexpaq 1:55a6170b404f 117 mbedtls_mpi_free( &L ); mbedtls_mpi_free( &U );
nexpaq 1:55a6170b404f 118 return( ret );
nexpaq 1:55a6170b404f 119 }
nexpaq 1:55a6170b404f 120
nexpaq 1:55a6170b404f 121 void mbedtls_dhm_init( mbedtls_dhm_context *ctx )
nexpaq 1:55a6170b404f 122 {
nexpaq 1:55a6170b404f 123 memset( ctx, 0, sizeof( mbedtls_dhm_context ) );
nexpaq 1:55a6170b404f 124 }
nexpaq 1:55a6170b404f 125
nexpaq 1:55a6170b404f 126 /*
nexpaq 1:55a6170b404f 127 * Parse the ServerKeyExchange parameters
nexpaq 1:55a6170b404f 128 */
nexpaq 1:55a6170b404f 129 int mbedtls_dhm_read_params( mbedtls_dhm_context *ctx,
nexpaq 1:55a6170b404f 130 unsigned char **p,
nexpaq 1:55a6170b404f 131 const unsigned char *end )
nexpaq 1:55a6170b404f 132 {
nexpaq 1:55a6170b404f 133 int ret;
nexpaq 1:55a6170b404f 134
nexpaq 1:55a6170b404f 135 if( ( ret = dhm_read_bignum( &ctx->P, p, end ) ) != 0 ||
nexpaq 1:55a6170b404f 136 ( ret = dhm_read_bignum( &ctx->G, p, end ) ) != 0 ||
nexpaq 1:55a6170b404f 137 ( ret = dhm_read_bignum( &ctx->GY, p, end ) ) != 0 )
nexpaq 1:55a6170b404f 138 return( ret );
nexpaq 1:55a6170b404f 139
nexpaq 1:55a6170b404f 140 if( ( ret = dhm_check_range( &ctx->GY, &ctx->P ) ) != 0 )
nexpaq 1:55a6170b404f 141 return( ret );
nexpaq 1:55a6170b404f 142
nexpaq 1:55a6170b404f 143 ctx->len = mbedtls_mpi_size( &ctx->P );
nexpaq 1:55a6170b404f 144
nexpaq 1:55a6170b404f 145 return( 0 );
nexpaq 1:55a6170b404f 146 }
nexpaq 1:55a6170b404f 147
nexpaq 1:55a6170b404f 148 /*
nexpaq 1:55a6170b404f 149 * Setup and write the ServerKeyExchange parameters
nexpaq 1:55a6170b404f 150 */
nexpaq 1:55a6170b404f 151 int mbedtls_dhm_make_params( mbedtls_dhm_context *ctx, int x_size,
nexpaq 1:55a6170b404f 152 unsigned char *output, size_t *olen,
nexpaq 1:55a6170b404f 153 int (*f_rng)(void *, unsigned char *, size_t),
nexpaq 1:55a6170b404f 154 void *p_rng )
nexpaq 1:55a6170b404f 155 {
nexpaq 1:55a6170b404f 156 int ret, count = 0;
nexpaq 1:55a6170b404f 157 size_t n1, n2, n3;
nexpaq 1:55a6170b404f 158 unsigned char *p;
nexpaq 1:55a6170b404f 159
nexpaq 1:55a6170b404f 160 if( mbedtls_mpi_cmp_int( &ctx->P, 0 ) == 0 )
nexpaq 1:55a6170b404f 161 return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
nexpaq 1:55a6170b404f 162
nexpaq 1:55a6170b404f 163 /*
nexpaq 1:55a6170b404f 164 * Generate X as large as possible ( < P )
nexpaq 1:55a6170b404f 165 */
nexpaq 1:55a6170b404f 166 do
nexpaq 1:55a6170b404f 167 {
nexpaq 1:55a6170b404f 168 mbedtls_mpi_fill_random( &ctx->X, x_size, f_rng, p_rng );
nexpaq 1:55a6170b404f 169
nexpaq 1:55a6170b404f 170 while( mbedtls_mpi_cmp_mpi( &ctx->X, &ctx->P ) >= 0 )
nexpaq 1:55a6170b404f 171 MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->X, 1 ) );
nexpaq 1:55a6170b404f 172
nexpaq 1:55a6170b404f 173 if( count++ > 10 )
nexpaq 1:55a6170b404f 174 return( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED );
nexpaq 1:55a6170b404f 175 }
nexpaq 1:55a6170b404f 176 while( dhm_check_range( &ctx->X, &ctx->P ) != 0 );
nexpaq 1:55a6170b404f 177
nexpaq 1:55a6170b404f 178 /*
nexpaq 1:55a6170b404f 179 * Calculate GX = G^X mod P
nexpaq 1:55a6170b404f 180 */
nexpaq 1:55a6170b404f 181 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->GX, &ctx->G, &ctx->X,
nexpaq 1:55a6170b404f 182 &ctx->P , &ctx->RP ) );
nexpaq 1:55a6170b404f 183
nexpaq 1:55a6170b404f 184 if( ( ret = dhm_check_range( &ctx->GX, &ctx->P ) ) != 0 )
nexpaq 1:55a6170b404f 185 return( ret );
nexpaq 1:55a6170b404f 186
nexpaq 1:55a6170b404f 187 /*
nexpaq 1:55a6170b404f 188 * export P, G, GX
nexpaq 1:55a6170b404f 189 */
nexpaq 1:55a6170b404f 190 #define DHM_MPI_EXPORT(X,n) \
nexpaq 1:55a6170b404f 191 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, p + 2, n ) ); \
nexpaq 1:55a6170b404f 192 *p++ = (unsigned char)( n >> 8 ); \
nexpaq 1:55a6170b404f 193 *p++ = (unsigned char)( n ); p += n;
nexpaq 1:55a6170b404f 194
nexpaq 1:55a6170b404f 195 n1 = mbedtls_mpi_size( &ctx->P );
nexpaq 1:55a6170b404f 196 n2 = mbedtls_mpi_size( &ctx->G );
nexpaq 1:55a6170b404f 197 n3 = mbedtls_mpi_size( &ctx->GX );
nexpaq 1:55a6170b404f 198
nexpaq 1:55a6170b404f 199 p = output;
nexpaq 1:55a6170b404f 200 DHM_MPI_EXPORT( &ctx->P , n1 );
nexpaq 1:55a6170b404f 201 DHM_MPI_EXPORT( &ctx->G , n2 );
nexpaq 1:55a6170b404f 202 DHM_MPI_EXPORT( &ctx->GX, n3 );
nexpaq 1:55a6170b404f 203
nexpaq 1:55a6170b404f 204 *olen = p - output;
nexpaq 1:55a6170b404f 205
nexpaq 1:55a6170b404f 206 ctx->len = n1;
nexpaq 1:55a6170b404f 207
nexpaq 1:55a6170b404f 208 cleanup:
nexpaq 1:55a6170b404f 209
nexpaq 1:55a6170b404f 210 if( ret != 0 )
nexpaq 1:55a6170b404f 211 return( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED + ret );
nexpaq 1:55a6170b404f 212
nexpaq 1:55a6170b404f 213 return( 0 );
nexpaq 1:55a6170b404f 214 }
nexpaq 1:55a6170b404f 215
nexpaq 1:55a6170b404f 216 /*
nexpaq 1:55a6170b404f 217 * Import the peer's public value G^Y
nexpaq 1:55a6170b404f 218 */
nexpaq 1:55a6170b404f 219 int mbedtls_dhm_read_public( mbedtls_dhm_context *ctx,
nexpaq 1:55a6170b404f 220 const unsigned char *input, size_t ilen )
nexpaq 1:55a6170b404f 221 {
nexpaq 1:55a6170b404f 222 int ret;
nexpaq 1:55a6170b404f 223
nexpaq 1:55a6170b404f 224 if( ctx == NULL || ilen < 1 || ilen > ctx->len )
nexpaq 1:55a6170b404f 225 return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
nexpaq 1:55a6170b404f 226
nexpaq 1:55a6170b404f 227 if( ( ret = mbedtls_mpi_read_binary( &ctx->GY, input, ilen ) ) != 0 )
nexpaq 1:55a6170b404f 228 return( MBEDTLS_ERR_DHM_READ_PUBLIC_FAILED + ret );
nexpaq 1:55a6170b404f 229
nexpaq 1:55a6170b404f 230 return( 0 );
nexpaq 1:55a6170b404f 231 }
nexpaq 1:55a6170b404f 232
nexpaq 1:55a6170b404f 233 /*
nexpaq 1:55a6170b404f 234 * Create own private value X and export G^X
nexpaq 1:55a6170b404f 235 */
nexpaq 1:55a6170b404f 236 int mbedtls_dhm_make_public( mbedtls_dhm_context *ctx, int x_size,
nexpaq 1:55a6170b404f 237 unsigned char *output, size_t olen,
nexpaq 1:55a6170b404f 238 int (*f_rng)(void *, unsigned char *, size_t),
nexpaq 1:55a6170b404f 239 void *p_rng )
nexpaq 1:55a6170b404f 240 {
nexpaq 1:55a6170b404f 241 int ret, count = 0;
nexpaq 1:55a6170b404f 242
nexpaq 1:55a6170b404f 243 if( ctx == NULL || olen < 1 || olen > ctx->len )
nexpaq 1:55a6170b404f 244 return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
nexpaq 1:55a6170b404f 245
nexpaq 1:55a6170b404f 246 if( mbedtls_mpi_cmp_int( &ctx->P, 0 ) == 0 )
nexpaq 1:55a6170b404f 247 return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
nexpaq 1:55a6170b404f 248
nexpaq 1:55a6170b404f 249 /*
nexpaq 1:55a6170b404f 250 * generate X and calculate GX = G^X mod P
nexpaq 1:55a6170b404f 251 */
nexpaq 1:55a6170b404f 252 do
nexpaq 1:55a6170b404f 253 {
nexpaq 1:55a6170b404f 254 mbedtls_mpi_fill_random( &ctx->X, x_size, f_rng, p_rng );
nexpaq 1:55a6170b404f 255
nexpaq 1:55a6170b404f 256 while( mbedtls_mpi_cmp_mpi( &ctx->X, &ctx->P ) >= 0 )
nexpaq 1:55a6170b404f 257 MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->X, 1 ) );
nexpaq 1:55a6170b404f 258
nexpaq 1:55a6170b404f 259 if( count++ > 10 )
nexpaq 1:55a6170b404f 260 return( MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED );
nexpaq 1:55a6170b404f 261 }
nexpaq 1:55a6170b404f 262 while( dhm_check_range( &ctx->X, &ctx->P ) != 0 );
nexpaq 1:55a6170b404f 263
nexpaq 1:55a6170b404f 264 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->GX, &ctx->G, &ctx->X,
nexpaq 1:55a6170b404f 265 &ctx->P , &ctx->RP ) );
nexpaq 1:55a6170b404f 266
nexpaq 1:55a6170b404f 267 if( ( ret = dhm_check_range( &ctx->GX, &ctx->P ) ) != 0 )
nexpaq 1:55a6170b404f 268 return( ret );
nexpaq 1:55a6170b404f 269
nexpaq 1:55a6170b404f 270 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->GX, output, olen ) );
nexpaq 1:55a6170b404f 271
nexpaq 1:55a6170b404f 272 cleanup:
nexpaq 1:55a6170b404f 273
nexpaq 1:55a6170b404f 274 if( ret != 0 )
nexpaq 1:55a6170b404f 275 return( MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED + ret );
nexpaq 1:55a6170b404f 276
nexpaq 1:55a6170b404f 277 return( 0 );
nexpaq 1:55a6170b404f 278 }
nexpaq 1:55a6170b404f 279
nexpaq 1:55a6170b404f 280 /*
nexpaq 1:55a6170b404f 281 * Use the blinding method and optimisation suggested in section 10 of:
nexpaq 1:55a6170b404f 282 * KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA,
nexpaq 1:55a6170b404f 283 * DSS, and other systems. In : Advances in Cryptology-CRYPTO'96. Springer
nexpaq 1:55a6170b404f 284 * Berlin Heidelberg, 1996. p. 104-113.
nexpaq 1:55a6170b404f 285 */
nexpaq 1:55a6170b404f 286 static int dhm_update_blinding( mbedtls_dhm_context *ctx,
nexpaq 1:55a6170b404f 287 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
nexpaq 1:55a6170b404f 288 {
nexpaq 1:55a6170b404f 289 int ret, count;
nexpaq 1:55a6170b404f 290
nexpaq 1:55a6170b404f 291 /*
nexpaq 1:55a6170b404f 292 * Don't use any blinding the first time a particular X is used,
nexpaq 1:55a6170b404f 293 * but remember it to use blinding next time.
nexpaq 1:55a6170b404f 294 */
nexpaq 1:55a6170b404f 295 if( mbedtls_mpi_cmp_mpi( &ctx->X, &ctx->pX ) != 0 )
nexpaq 1:55a6170b404f 296 {
nexpaq 1:55a6170b404f 297 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &ctx->pX, &ctx->X ) );
nexpaq 1:55a6170b404f 298 MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &ctx->Vi, 1 ) );
nexpaq 1:55a6170b404f 299 MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &ctx->Vf, 1 ) );
nexpaq 1:55a6170b404f 300
nexpaq 1:55a6170b404f 301 return( 0 );
nexpaq 1:55a6170b404f 302 }
nexpaq 1:55a6170b404f 303
nexpaq 1:55a6170b404f 304 /*
nexpaq 1:55a6170b404f 305 * Ok, we need blinding. Can we re-use existing values?
nexpaq 1:55a6170b404f 306 * If yes, just update them by squaring them.
nexpaq 1:55a6170b404f 307 */
nexpaq 1:55a6170b404f 308 if( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) != 0 )
nexpaq 1:55a6170b404f 309 {
nexpaq 1:55a6170b404f 310 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &ctx->Vi ) );
nexpaq 1:55a6170b404f 311 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->P ) );
nexpaq 1:55a6170b404f 312
nexpaq 1:55a6170b404f 313 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, &ctx->Vf ) );
nexpaq 1:55a6170b404f 314 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->P ) );
nexpaq 1:55a6170b404f 315
nexpaq 1:55a6170b404f 316 return( 0 );
nexpaq 1:55a6170b404f 317 }
nexpaq 1:55a6170b404f 318
nexpaq 1:55a6170b404f 319 /*
nexpaq 1:55a6170b404f 320 * We need to generate blinding values from scratch
nexpaq 1:55a6170b404f 321 */
nexpaq 1:55a6170b404f 322
nexpaq 1:55a6170b404f 323 /* Vi = random( 2, P-1 ) */
nexpaq 1:55a6170b404f 324 count = 0;
nexpaq 1:55a6170b404f 325 do
nexpaq 1:55a6170b404f 326 {
nexpaq 1:55a6170b404f 327 mbedtls_mpi_fill_random( &ctx->Vi, mbedtls_mpi_size( &ctx->P ), f_rng, p_rng );
nexpaq 1:55a6170b404f 328
nexpaq 1:55a6170b404f 329 while( mbedtls_mpi_cmp_mpi( &ctx->Vi, &ctx->P ) >= 0 )
nexpaq 1:55a6170b404f 330 MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->Vi, 1 ) );
nexpaq 1:55a6170b404f 331
nexpaq 1:55a6170b404f 332 if( count++ > 10 )
nexpaq 1:55a6170b404f 333 return( MBEDTLS_ERR_MPI_NOT_ACCEPTABLE );
nexpaq 1:55a6170b404f 334 }
nexpaq 1:55a6170b404f 335 while( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) <= 0 );
nexpaq 1:55a6170b404f 336
nexpaq 1:55a6170b404f 337 /* Vf = Vi^-X mod P */
nexpaq 1:55a6170b404f 338 MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vf, &ctx->Vi, &ctx->P ) );
nexpaq 1:55a6170b404f 339 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->Vf, &ctx->Vf, &ctx->X, &ctx->P, &ctx->RP ) );
nexpaq 1:55a6170b404f 340
nexpaq 1:55a6170b404f 341 cleanup:
nexpaq 1:55a6170b404f 342 return( ret );
nexpaq 1:55a6170b404f 343 }
nexpaq 1:55a6170b404f 344
nexpaq 1:55a6170b404f 345 /*
nexpaq 1:55a6170b404f 346 * Derive and export the shared secret (G^Y)^X mod P
nexpaq 1:55a6170b404f 347 */
nexpaq 1:55a6170b404f 348 int mbedtls_dhm_calc_secret( mbedtls_dhm_context *ctx,
nexpaq 1:55a6170b404f 349 unsigned char *output, size_t output_size, size_t *olen,
nexpaq 1:55a6170b404f 350 int (*f_rng)(void *, unsigned char *, size_t),
nexpaq 1:55a6170b404f 351 void *p_rng )
nexpaq 1:55a6170b404f 352 {
nexpaq 1:55a6170b404f 353 int ret;
nexpaq 1:55a6170b404f 354 mbedtls_mpi GYb;
nexpaq 1:55a6170b404f 355
nexpaq 1:55a6170b404f 356 if( ctx == NULL || output_size < ctx->len )
nexpaq 1:55a6170b404f 357 return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
nexpaq 1:55a6170b404f 358
nexpaq 1:55a6170b404f 359 if( ( ret = dhm_check_range( &ctx->GY, &ctx->P ) ) != 0 )
nexpaq 1:55a6170b404f 360 return( ret );
nexpaq 1:55a6170b404f 361
nexpaq 1:55a6170b404f 362 mbedtls_mpi_init( &GYb );
nexpaq 1:55a6170b404f 363
nexpaq 1:55a6170b404f 364 /* Blind peer's value */
nexpaq 1:55a6170b404f 365 if( f_rng != NULL )
nexpaq 1:55a6170b404f 366 {
nexpaq 1:55a6170b404f 367 MBEDTLS_MPI_CHK( dhm_update_blinding( ctx, f_rng, p_rng ) );
nexpaq 1:55a6170b404f 368 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &GYb, &ctx->GY, &ctx->Vi ) );
nexpaq 1:55a6170b404f 369 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &GYb, &GYb, &ctx->P ) );
nexpaq 1:55a6170b404f 370 }
nexpaq 1:55a6170b404f 371 else
nexpaq 1:55a6170b404f 372 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &GYb, &ctx->GY ) );
nexpaq 1:55a6170b404f 373
nexpaq 1:55a6170b404f 374 /* Do modular exponentiation */
nexpaq 1:55a6170b404f 375 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->K, &GYb, &ctx->X,
nexpaq 1:55a6170b404f 376 &ctx->P, &ctx->RP ) );
nexpaq 1:55a6170b404f 377
nexpaq 1:55a6170b404f 378 /* Unblind secret value */
nexpaq 1:55a6170b404f 379 if( f_rng != NULL )
nexpaq 1:55a6170b404f 380 {
nexpaq 1:55a6170b404f 381 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->K, &ctx->K, &ctx->Vf ) );
nexpaq 1:55a6170b404f 382 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->K, &ctx->K, &ctx->P ) );
nexpaq 1:55a6170b404f 383 }
nexpaq 1:55a6170b404f 384
nexpaq 1:55a6170b404f 385 *olen = mbedtls_mpi_size( &ctx->K );
nexpaq 1:55a6170b404f 386
nexpaq 1:55a6170b404f 387 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->K, output, *olen ) );
nexpaq 1:55a6170b404f 388
nexpaq 1:55a6170b404f 389 cleanup:
nexpaq 1:55a6170b404f 390 mbedtls_mpi_free( &GYb );
nexpaq 1:55a6170b404f 391
nexpaq 1:55a6170b404f 392 if( ret != 0 )
nexpaq 1:55a6170b404f 393 return( MBEDTLS_ERR_DHM_CALC_SECRET_FAILED + ret );
nexpaq 1:55a6170b404f 394
nexpaq 1:55a6170b404f 395 return( 0 );
nexpaq 1:55a6170b404f 396 }
nexpaq 1:55a6170b404f 397
nexpaq 1:55a6170b404f 398 /*
nexpaq 1:55a6170b404f 399 * Free the components of a DHM key
nexpaq 1:55a6170b404f 400 */
nexpaq 1:55a6170b404f 401 void mbedtls_dhm_free( mbedtls_dhm_context *ctx )
nexpaq 1:55a6170b404f 402 {
nexpaq 1:55a6170b404f 403 mbedtls_mpi_free( &ctx->pX); mbedtls_mpi_free( &ctx->Vf ); mbedtls_mpi_free( &ctx->Vi );
nexpaq 1:55a6170b404f 404 mbedtls_mpi_free( &ctx->RP ); mbedtls_mpi_free( &ctx->K ); mbedtls_mpi_free( &ctx->GY );
nexpaq 1:55a6170b404f 405 mbedtls_mpi_free( &ctx->GX ); mbedtls_mpi_free( &ctx->X ); mbedtls_mpi_free( &ctx->G );
nexpaq 1:55a6170b404f 406 mbedtls_mpi_free( &ctx->P );
nexpaq 1:55a6170b404f 407
nexpaq 1:55a6170b404f 408 mbedtls_zeroize( ctx, sizeof( mbedtls_dhm_context ) );
nexpaq 1:55a6170b404f 409 }
nexpaq 1:55a6170b404f 410
nexpaq 1:55a6170b404f 411 #if defined(MBEDTLS_ASN1_PARSE_C)
nexpaq 1:55a6170b404f 412 /*
nexpaq 1:55a6170b404f 413 * Parse DHM parameters
nexpaq 1:55a6170b404f 414 */
nexpaq 1:55a6170b404f 415 int mbedtls_dhm_parse_dhm( mbedtls_dhm_context *dhm, const unsigned char *dhmin,
nexpaq 1:55a6170b404f 416 size_t dhminlen )
nexpaq 1:55a6170b404f 417 {
nexpaq 1:55a6170b404f 418 int ret;
nexpaq 1:55a6170b404f 419 size_t len;
nexpaq 1:55a6170b404f 420 unsigned char *p, *end;
nexpaq 1:55a6170b404f 421 #if defined(MBEDTLS_PEM_PARSE_C)
nexpaq 1:55a6170b404f 422 mbedtls_pem_context pem;
nexpaq 1:55a6170b404f 423
nexpaq 1:55a6170b404f 424 mbedtls_pem_init( &pem );
nexpaq 1:55a6170b404f 425
nexpaq 1:55a6170b404f 426 /* Avoid calling mbedtls_pem_read_buffer() on non-null-terminated string */
nexpaq 1:55a6170b404f 427 if( dhminlen == 0 || dhmin[dhminlen - 1] != '\0' )
nexpaq 1:55a6170b404f 428 ret = MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT;
nexpaq 1:55a6170b404f 429 else
nexpaq 1:55a6170b404f 430 ret = mbedtls_pem_read_buffer( &pem,
nexpaq 1:55a6170b404f 431 "-----BEGIN DH PARAMETERS-----",
nexpaq 1:55a6170b404f 432 "-----END DH PARAMETERS-----",
nexpaq 1:55a6170b404f 433 dhmin, NULL, 0, &dhminlen );
nexpaq 1:55a6170b404f 434
nexpaq 1:55a6170b404f 435 if( ret == 0 )
nexpaq 1:55a6170b404f 436 {
nexpaq 1:55a6170b404f 437 /*
nexpaq 1:55a6170b404f 438 * Was PEM encoded
nexpaq 1:55a6170b404f 439 */
nexpaq 1:55a6170b404f 440 dhminlen = pem.buflen;
nexpaq 1:55a6170b404f 441 }
nexpaq 1:55a6170b404f 442 else if( ret != MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT )
nexpaq 1:55a6170b404f 443 goto exit;
nexpaq 1:55a6170b404f 444
nexpaq 1:55a6170b404f 445 p = ( ret == 0 ) ? pem.buf : (unsigned char *) dhmin;
nexpaq 1:55a6170b404f 446 #else
nexpaq 1:55a6170b404f 447 p = (unsigned char *) dhmin;
nexpaq 1:55a6170b404f 448 #endif /* MBEDTLS_PEM_PARSE_C */
nexpaq 1:55a6170b404f 449 end = p + dhminlen;
nexpaq 1:55a6170b404f 450
nexpaq 1:55a6170b404f 451 /*
nexpaq 1:55a6170b404f 452 * DHParams ::= SEQUENCE {
nexpaq 1:55a6170b404f 453 * prime INTEGER, -- P
nexpaq 1:55a6170b404f 454 * generator INTEGER, -- g
nexpaq 1:55a6170b404f 455 * privateValueLength INTEGER OPTIONAL
nexpaq 1:55a6170b404f 456 * }
nexpaq 1:55a6170b404f 457 */
nexpaq 1:55a6170b404f 458 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
nexpaq 1:55a6170b404f 459 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
nexpaq 1:55a6170b404f 460 {
nexpaq 1:55a6170b404f 461 ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
nexpaq 1:55a6170b404f 462 goto exit;
nexpaq 1:55a6170b404f 463 }
nexpaq 1:55a6170b404f 464
nexpaq 1:55a6170b404f 465 end = p + len;
nexpaq 1:55a6170b404f 466
nexpaq 1:55a6170b404f 467 if( ( ret = mbedtls_asn1_get_mpi( &p, end, &dhm->P ) ) != 0 ||
nexpaq 1:55a6170b404f 468 ( ret = mbedtls_asn1_get_mpi( &p, end, &dhm->G ) ) != 0 )
nexpaq 1:55a6170b404f 469 {
nexpaq 1:55a6170b404f 470 ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
nexpaq 1:55a6170b404f 471 goto exit;
nexpaq 1:55a6170b404f 472 }
nexpaq 1:55a6170b404f 473
nexpaq 1:55a6170b404f 474 if( p != end )
nexpaq 1:55a6170b404f 475 {
nexpaq 1:55a6170b404f 476 /* This might be the optional privateValueLength.
nexpaq 1:55a6170b404f 477 * If so, we can cleanly discard it */
nexpaq 1:55a6170b404f 478 mbedtls_mpi rec;
nexpaq 1:55a6170b404f 479 mbedtls_mpi_init( &rec );
nexpaq 1:55a6170b404f 480 ret = mbedtls_asn1_get_mpi( &p, end, &rec );
nexpaq 1:55a6170b404f 481 mbedtls_mpi_free( &rec );
nexpaq 1:55a6170b404f 482 if ( ret != 0 )
nexpaq 1:55a6170b404f 483 {
nexpaq 1:55a6170b404f 484 ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
nexpaq 1:55a6170b404f 485 goto exit;
nexpaq 1:55a6170b404f 486 }
nexpaq 1:55a6170b404f 487 if ( p != end )
nexpaq 1:55a6170b404f 488 {
nexpaq 1:55a6170b404f 489 ret = MBEDTLS_ERR_DHM_INVALID_FORMAT +
nexpaq 1:55a6170b404f 490 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
nexpaq 1:55a6170b404f 491 goto exit;
nexpaq 1:55a6170b404f 492 }
nexpaq 1:55a6170b404f 493 }
nexpaq 1:55a6170b404f 494
nexpaq 1:55a6170b404f 495 ret = 0;
nexpaq 1:55a6170b404f 496
nexpaq 1:55a6170b404f 497 dhm->len = mbedtls_mpi_size( &dhm->P );
nexpaq 1:55a6170b404f 498
nexpaq 1:55a6170b404f 499 exit:
nexpaq 1:55a6170b404f 500 #if defined(MBEDTLS_PEM_PARSE_C)
nexpaq 1:55a6170b404f 501 mbedtls_pem_free( &pem );
nexpaq 1:55a6170b404f 502 #endif
nexpaq 1:55a6170b404f 503 if( ret != 0 )
nexpaq 1:55a6170b404f 504 mbedtls_dhm_free( dhm );
nexpaq 1:55a6170b404f 505
nexpaq 1:55a6170b404f 506 return( ret );
nexpaq 1:55a6170b404f 507 }
nexpaq 1:55a6170b404f 508
nexpaq 1:55a6170b404f 509 #if defined(MBEDTLS_FS_IO)
nexpaq 1:55a6170b404f 510 /*
nexpaq 1:55a6170b404f 511 * Load all data from a file into a given buffer.
nexpaq 1:55a6170b404f 512 *
nexpaq 1:55a6170b404f 513 * The file is expected to contain either PEM or DER encoded data.
nexpaq 1:55a6170b404f 514 * A terminating null byte is always appended. It is included in the announced
nexpaq 1:55a6170b404f 515 * length only if the data looks like it is PEM encoded.
nexpaq 1:55a6170b404f 516 */
nexpaq 1:55a6170b404f 517 static int load_file( const char *path, unsigned char **buf, size_t *n )
nexpaq 1:55a6170b404f 518 {
nexpaq 1:55a6170b404f 519 FILE *f;
nexpaq 1:55a6170b404f 520 long size;
nexpaq 1:55a6170b404f 521
nexpaq 1:55a6170b404f 522 if( ( f = fopen( path, "rb" ) ) == NULL )
nexpaq 1:55a6170b404f 523 return( MBEDTLS_ERR_DHM_FILE_IO_ERROR );
nexpaq 1:55a6170b404f 524
nexpaq 1:55a6170b404f 525 fseek( f, 0, SEEK_END );
nexpaq 1:55a6170b404f 526 if( ( size = ftell( f ) ) == -1 )
nexpaq 1:55a6170b404f 527 {
nexpaq 1:55a6170b404f 528 fclose( f );
nexpaq 1:55a6170b404f 529 return( MBEDTLS_ERR_DHM_FILE_IO_ERROR );
nexpaq 1:55a6170b404f 530 }
nexpaq 1:55a6170b404f 531 fseek( f, 0, SEEK_SET );
nexpaq 1:55a6170b404f 532
nexpaq 1:55a6170b404f 533 *n = (size_t) size;
nexpaq 1:55a6170b404f 534
nexpaq 1:55a6170b404f 535 if( *n + 1 == 0 ||
nexpaq 1:55a6170b404f 536 ( *buf = mbedtls_calloc( 1, *n + 1 ) ) == NULL )
nexpaq 1:55a6170b404f 537 {
nexpaq 1:55a6170b404f 538 fclose( f );
nexpaq 1:55a6170b404f 539 return( MBEDTLS_ERR_DHM_ALLOC_FAILED );
nexpaq 1:55a6170b404f 540 }
nexpaq 1:55a6170b404f 541
nexpaq 1:55a6170b404f 542 if( fread( *buf, 1, *n, f ) != *n )
nexpaq 1:55a6170b404f 543 {
nexpaq 1:55a6170b404f 544 fclose( f );
nexpaq 1:55a6170b404f 545 mbedtls_free( *buf );
nexpaq 1:55a6170b404f 546 return( MBEDTLS_ERR_DHM_FILE_IO_ERROR );
nexpaq 1:55a6170b404f 547 }
nexpaq 1:55a6170b404f 548
nexpaq 1:55a6170b404f 549 fclose( f );
nexpaq 1:55a6170b404f 550
nexpaq 1:55a6170b404f 551 (*buf)[*n] = '\0';
nexpaq 1:55a6170b404f 552
nexpaq 1:55a6170b404f 553 if( strstr( (const char *) *buf, "-----BEGIN " ) != NULL )
nexpaq 1:55a6170b404f 554 ++*n;
nexpaq 1:55a6170b404f 555
nexpaq 1:55a6170b404f 556 return( 0 );
nexpaq 1:55a6170b404f 557 }
nexpaq 1:55a6170b404f 558
nexpaq 1:55a6170b404f 559 /*
nexpaq 1:55a6170b404f 560 * Load and parse DHM parameters
nexpaq 1:55a6170b404f 561 */
nexpaq 1:55a6170b404f 562 int mbedtls_dhm_parse_dhmfile( mbedtls_dhm_context *dhm, const char *path )
nexpaq 1:55a6170b404f 563 {
nexpaq 1:55a6170b404f 564 int ret;
nexpaq 1:55a6170b404f 565 size_t n;
nexpaq 1:55a6170b404f 566 unsigned char *buf;
nexpaq 1:55a6170b404f 567
nexpaq 1:55a6170b404f 568 if( ( ret = load_file( path, &buf, &n ) ) != 0 )
nexpaq 1:55a6170b404f 569 return( ret );
nexpaq 1:55a6170b404f 570
nexpaq 1:55a6170b404f 571 ret = mbedtls_dhm_parse_dhm( dhm, buf, n );
nexpaq 1:55a6170b404f 572
nexpaq 1:55a6170b404f 573 mbedtls_zeroize( buf, n );
nexpaq 1:55a6170b404f 574 mbedtls_free( buf );
nexpaq 1:55a6170b404f 575
nexpaq 1:55a6170b404f 576 return( ret );
nexpaq 1:55a6170b404f 577 }
nexpaq 1:55a6170b404f 578 #endif /* MBEDTLS_FS_IO */
nexpaq 1:55a6170b404f 579 #endif /* MBEDTLS_ASN1_PARSE_C */
nexpaq 1:55a6170b404f 580
nexpaq 1:55a6170b404f 581 #if defined(MBEDTLS_SELF_TEST)
nexpaq 1:55a6170b404f 582
nexpaq 1:55a6170b404f 583 static const char mbedtls_test_dhm_params[] =
nexpaq 1:55a6170b404f 584 "-----BEGIN DH PARAMETERS-----\r\n"
nexpaq 1:55a6170b404f 585 "MIGHAoGBAJ419DBEOgmQTzo5qXl5fQcN9TN455wkOL7052HzxxRVMyhYmwQcgJvh\r\n"
nexpaq 1:55a6170b404f 586 "1sa18fyfR9OiVEMYglOpkqVoGLN7qd5aQNNi5W7/C+VBdHTBJcGZJyyP5B3qcz32\r\n"
nexpaq 1:55a6170b404f 587 "9mLJKudlVudV0Qxk5qUJaPZ/xupz0NyoVpviuiBOI1gNi8ovSXWzAgEC\r\n"
nexpaq 1:55a6170b404f 588 "-----END DH PARAMETERS-----\r\n";
nexpaq 1:55a6170b404f 589
nexpaq 1:55a6170b404f 590 static const size_t mbedtls_test_dhm_params_len = sizeof( mbedtls_test_dhm_params );
nexpaq 1:55a6170b404f 591
nexpaq 1:55a6170b404f 592 /*
nexpaq 1:55a6170b404f 593 * Checkup routine
nexpaq 1:55a6170b404f 594 */
nexpaq 1:55a6170b404f 595 int mbedtls_dhm_self_test( int verbose )
nexpaq 1:55a6170b404f 596 {
nexpaq 1:55a6170b404f 597 int ret;
nexpaq 1:55a6170b404f 598 mbedtls_dhm_context dhm;
nexpaq 1:55a6170b404f 599
nexpaq 1:55a6170b404f 600 mbedtls_dhm_init( &dhm );
nexpaq 1:55a6170b404f 601
nexpaq 1:55a6170b404f 602 if( verbose != 0 )
nexpaq 1:55a6170b404f 603 mbedtls_printf( " DHM parameter load: " );
nexpaq 1:55a6170b404f 604
nexpaq 1:55a6170b404f 605 if( ( ret = mbedtls_dhm_parse_dhm( &dhm,
nexpaq 1:55a6170b404f 606 (const unsigned char *) mbedtls_test_dhm_params,
nexpaq 1:55a6170b404f 607 mbedtls_test_dhm_params_len ) ) != 0 )
nexpaq 1:55a6170b404f 608 {
nexpaq 1:55a6170b404f 609 if( verbose != 0 )
nexpaq 1:55a6170b404f 610 mbedtls_printf( "failed\n" );
nexpaq 1:55a6170b404f 611
nexpaq 1:55a6170b404f 612 ret = 1;
nexpaq 1:55a6170b404f 613 goto exit;
nexpaq 1:55a6170b404f 614 }
nexpaq 1:55a6170b404f 615
nexpaq 1:55a6170b404f 616 if( verbose != 0 )
nexpaq 1:55a6170b404f 617 mbedtls_printf( "passed\n\n" );
nexpaq 1:55a6170b404f 618
nexpaq 1:55a6170b404f 619 exit:
nexpaq 1:55a6170b404f 620 mbedtls_dhm_free( &dhm );
nexpaq 1:55a6170b404f 621
nexpaq 1:55a6170b404f 622 return( ret );
nexpaq 1:55a6170b404f 623 }
nexpaq 1:55a6170b404f 624
nexpaq 1:55a6170b404f 625 #endif /* MBEDTLS_SELF_TEST */
nexpaq 1:55a6170b404f 626
nexpaq 1:55a6170b404f 627 #endif /* MBEDTLS_DHM_C */