1 // SPDX-License-Identifier: Apache-2.0 2 /* 3 * The RSA public-key cryptosystem 4 * 5 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 6 * 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may 8 * not use this file except in compliance with the License. 9 * You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, software 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 * See the License for the specific language governing permissions and 17 * limitations under the License. 18 * 19 * This file is part of mbed TLS (https://tls.mbed.org) 20 */ 21 22 /* 23 * The following sources were referenced in the design of this implementation 24 * of the RSA algorithm: 25 * 26 * [1] A method for obtaining digital signatures and public-key cryptosystems 27 * R Rivest, A Shamir, and L Adleman 28 * http://people.csail.mit.edu/rivest/pubs.html#RSA78 29 * 30 * [2] Handbook of Applied Cryptography - 1997, Chapter 8 31 * Menezes, van Oorschot and Vanstone 32 * 33 * [3] Malware Guard Extension: Using SGX to Conceal Cache Attacks 34 * Michael Schwarz, Samuel Weiser, Daniel Gruss, Clémentine Maurice and 35 * Stefan Mangard 36 * https://arxiv.org/abs/1702.08719v2 37 * 38 */ 39 40 #if !defined(MBEDTLS_CONFIG_FILE) 41 #include "mbedtls/config.h" 42 #else 43 #include MBEDTLS_CONFIG_FILE 44 #endif 45 46 #if defined(MBEDTLS_RSA_C) 47 48 #include "mbedtls/rsa.h" 49 #include "mbedtls/rsa_internal.h" 50 #include "mbedtls/oid.h" 51 #include "mbedtls/platform_util.h" 52 53 #include <string.h> 54 55 #if defined(MBEDTLS_PKCS1_V21) 56 #include "mbedtls/md.h" 57 #endif 58 59 #if defined(MBEDTLS_PKCS1_V15) && !defined(__OpenBSD__) 60 #include <stdlib.h> 61 #endif 62 63 #if defined(MBEDTLS_PLATFORM_C) 64 #include "mbedtls/platform.h" 65 #else 66 #include <stdio.h> 67 #define mbedtls_printf printf 68 #define mbedtls_calloc calloc 69 #define mbedtls_free free 70 #endif 71 72 #if !defined(MBEDTLS_RSA_ALT) 73 74 /* Parameter validation macros */ 75 #define RSA_VALIDATE_RET( cond ) \ 76 MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_RSA_BAD_INPUT_DATA ) 77 #define RSA_VALIDATE( cond ) \ 78 MBEDTLS_INTERNAL_VALIDATE( cond ) 79 80 #if defined(MBEDTLS_PKCS1_V15) 81 /* constant-time buffer comparison */ 82 static inline int mbedtls_safer_memcmp( const void *a, const void *b, size_t n ) 83 { 84 size_t i; 85 const unsigned char *A = (const unsigned char *) a; 86 const unsigned char *B = (const unsigned char *) b; 87 unsigned char diff = 0; 88 89 for( i = 0; i < n; i++ ) 90 diff |= A[i] ^ B[i]; 91 92 return( diff ); 93 } 94 #endif /* MBEDTLS_PKCS1_V15 */ 95 96 int mbedtls_rsa_import( mbedtls_rsa_context *ctx, 97 const mbedtls_mpi *N, 98 const mbedtls_mpi *P, const mbedtls_mpi *Q, 99 const mbedtls_mpi *D, const mbedtls_mpi *E ) 100 { 101 int ret; 102 RSA_VALIDATE_RET( ctx != NULL ); 103 104 if( ( N != NULL && ( ret = mbedtls_mpi_copy( &ctx->N, N ) ) != 0 ) || 105 ( P != NULL && ( ret = mbedtls_mpi_copy( &ctx->P, P ) ) != 0 ) || 106 ( Q != NULL && ( ret = mbedtls_mpi_copy( &ctx->Q, Q ) ) != 0 ) || 107 ( D != NULL && ( ret = mbedtls_mpi_copy( &ctx->D, D ) ) != 0 ) || 108 ( E != NULL && ( ret = mbedtls_mpi_copy( &ctx->E, E ) ) != 0 ) ) 109 { 110 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 111 } 112 113 if( N != NULL ) 114 ctx->len = mbedtls_mpi_size( &ctx->N ); 115 116 return( 0 ); 117 } 118 119 int mbedtls_rsa_import_raw( mbedtls_rsa_context *ctx, 120 unsigned char const *N, size_t N_len, 121 unsigned char const *P, size_t P_len, 122 unsigned char const *Q, size_t Q_len, 123 unsigned char const *D, size_t D_len, 124 unsigned char const *E, size_t E_len ) 125 { 126 int ret = 0; 127 RSA_VALIDATE_RET( ctx != NULL ); 128 129 if( N != NULL ) 130 { 131 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->N, N, N_len ) ); 132 ctx->len = mbedtls_mpi_size( &ctx->N ); 133 } 134 135 if( P != NULL ) 136 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->P, P, P_len ) ); 137 138 if( Q != NULL ) 139 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->Q, Q, Q_len ) ); 140 141 if( D != NULL ) 142 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->D, D, D_len ) ); 143 144 if( E != NULL ) 145 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->E, E, E_len ) ); 146 147 cleanup: 148 149 if( ret != 0 ) 150 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 151 152 return( 0 ); 153 } 154 155 /* 156 * Checks whether the context fields are set in such a way 157 * that the RSA primitives will be able to execute without error. 158 * It does *not* make guarantees for consistency of the parameters. 159 */ 160 static int rsa_check_context( mbedtls_rsa_context const *ctx, int is_priv, 161 int blinding_needed ) 162 { 163 #if !defined(MBEDTLS_RSA_NO_CRT) 164 /* blinding_needed is only used for NO_CRT to decide whether 165 * P,Q need to be present or not. */ 166 ((void) blinding_needed); 167 #endif 168 169 if( ctx->len != mbedtls_mpi_size( &ctx->N ) || 170 ctx->len > MBEDTLS_MPI_MAX_SIZE ) 171 { 172 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 173 } 174 175 /* 176 * 1. Modular exponentiation needs positive, odd moduli. 177 */ 178 179 /* Modular exponentiation wrt. N is always used for 180 * RSA public key operations. */ 181 if( mbedtls_mpi_cmp_int( &ctx->N, 0 ) <= 0 || 182 mbedtls_mpi_get_bit( &ctx->N, 0 ) == 0 ) 183 { 184 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 185 } 186 187 #if !defined(MBEDTLS_RSA_NO_CRT) 188 /* Modular exponentiation for P and Q is only 189 * used for private key operations and if CRT 190 * is used. */ 191 if( is_priv && 192 ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) <= 0 || 193 mbedtls_mpi_get_bit( &ctx->P, 0 ) == 0 || 194 mbedtls_mpi_cmp_int( &ctx->Q, 0 ) <= 0 || 195 mbedtls_mpi_get_bit( &ctx->Q, 0 ) == 0 ) ) 196 { 197 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 198 } 199 #endif /* !MBEDTLS_RSA_NO_CRT */ 200 201 /* 202 * 2. Exponents must be positive 203 */ 204 205 /* Always need E for public key operations */ 206 if( mbedtls_mpi_cmp_int( &ctx->E, 0 ) <= 0 ) 207 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 208 209 #if defined(MBEDTLS_RSA_NO_CRT) 210 /* For private key operations, use D or DP & DQ 211 * as (unblinded) exponents. */ 212 if( is_priv && mbedtls_mpi_cmp_int( &ctx->D, 0 ) <= 0 ) 213 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 214 #else 215 if( is_priv && 216 ( mbedtls_mpi_cmp_int( &ctx->DP, 0 ) <= 0 || 217 mbedtls_mpi_cmp_int( &ctx->DQ, 0 ) <= 0 ) ) 218 { 219 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 220 } 221 #endif /* MBEDTLS_RSA_NO_CRT */ 222 223 /* Blinding shouldn't make exponents negative either, 224 * so check that P, Q >= 1 if that hasn't yet been 225 * done as part of 1. */ 226 #if defined(MBEDTLS_RSA_NO_CRT) 227 if( is_priv && blinding_needed && 228 ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) <= 0 || 229 mbedtls_mpi_cmp_int( &ctx->Q, 0 ) <= 0 ) ) 230 { 231 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 232 } 233 #endif 234 235 /* It wouldn't lead to an error if it wasn't satisfied, 236 * but check for QP >= 1 nonetheless. */ 237 #if !defined(MBEDTLS_RSA_NO_CRT) 238 if( is_priv && 239 mbedtls_mpi_cmp_int( &ctx->QP, 0 ) <= 0 ) 240 { 241 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 242 } 243 #endif 244 245 return( 0 ); 246 } 247 248 int mbedtls_rsa_complete( mbedtls_rsa_context *ctx ) 249 { 250 int ret = 0; 251 int have_N, have_P, have_Q, have_D, have_E; 252 int n_missing, pq_missing, d_missing, is_pub, is_priv; 253 254 RSA_VALIDATE_RET( ctx != NULL ); 255 256 have_N = ( mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 ); 257 have_P = ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 ); 258 have_Q = ( mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 ); 259 have_D = ( mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 ); 260 have_E = ( mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0 ); 261 262 /* 263 * Check whether provided parameters are enough 264 * to deduce all others. The following incomplete 265 * parameter sets for private keys are supported: 266 * 267 * (1) P, Q missing. 268 * (2) D and potentially N missing. 269 * 270 */ 271 272 n_missing = have_P && have_Q && have_D && have_E; 273 pq_missing = have_N && !have_P && !have_Q && have_D && have_E; 274 d_missing = have_P && have_Q && !have_D && have_E; 275 is_pub = have_N && !have_P && !have_Q && !have_D && have_E; 276 277 /* These three alternatives are mutually exclusive */ 278 is_priv = n_missing || pq_missing || d_missing; 279 280 if( !is_priv && !is_pub ) 281 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 282 283 /* 284 * Step 1: Deduce N if P, Q are provided. 285 */ 286 287 if( !have_N && have_P && have_Q ) 288 { 289 if( ( ret = mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P, 290 &ctx->Q ) ) != 0 ) 291 { 292 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 293 } 294 295 ctx->len = mbedtls_mpi_size( &ctx->N ); 296 } 297 298 /* 299 * Step 2: Deduce and verify all remaining core parameters. 300 */ 301 302 if( pq_missing ) 303 { 304 ret = mbedtls_rsa_deduce_primes( &ctx->N, &ctx->E, &ctx->D, 305 &ctx->P, &ctx->Q ); 306 if( ret != 0 ) 307 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 308 309 } 310 else if( d_missing ) 311 { 312 if( ( ret = mbedtls_rsa_deduce_private_exponent( &ctx->P, 313 &ctx->Q, 314 &ctx->E, 315 &ctx->D ) ) != 0 ) 316 { 317 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 318 } 319 } 320 321 /* 322 * Step 3: Deduce all additional parameters specific 323 * to our current RSA implementation. 324 */ 325 326 #if !defined(MBEDTLS_RSA_NO_CRT) 327 if( is_priv ) 328 { 329 ret = mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D, 330 &ctx->DP, &ctx->DQ, &ctx->QP ); 331 if( ret != 0 ) 332 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 333 } 334 #endif /* MBEDTLS_RSA_NO_CRT */ 335 336 /* 337 * Step 3: Basic sanity checks 338 */ 339 340 return( rsa_check_context( ctx, is_priv, 1 ) ); 341 } 342 343 int mbedtls_rsa_export_raw( const mbedtls_rsa_context *ctx, 344 unsigned char *N, size_t N_len, 345 unsigned char *P, size_t P_len, 346 unsigned char *Q, size_t Q_len, 347 unsigned char *D, size_t D_len, 348 unsigned char *E, size_t E_len ) 349 { 350 int ret = 0; 351 int is_priv; 352 RSA_VALIDATE_RET( ctx != NULL ); 353 354 /* Check if key is private or public */ 355 is_priv = 356 mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 && 357 mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 && 358 mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 && 359 mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 && 360 mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0; 361 362 if( !is_priv ) 363 { 364 /* If we're trying to export private parameters for a public key, 365 * something must be wrong. */ 366 if( P != NULL || Q != NULL || D != NULL ) 367 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 368 369 } 370 371 if( N != NULL ) 372 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->N, N, N_len ) ); 373 374 if( P != NULL ) 375 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->P, P, P_len ) ); 376 377 if( Q != NULL ) 378 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->Q, Q, Q_len ) ); 379 380 if( D != NULL ) 381 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->D, D, D_len ) ); 382 383 if( E != NULL ) 384 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->E, E, E_len ) ); 385 386 cleanup: 387 388 return( ret ); 389 } 390 391 int mbedtls_rsa_export( const mbedtls_rsa_context *ctx, 392 mbedtls_mpi *N, mbedtls_mpi *P, mbedtls_mpi *Q, 393 mbedtls_mpi *D, mbedtls_mpi *E ) 394 { 395 int ret; 396 int is_priv; 397 RSA_VALIDATE_RET( ctx != NULL ); 398 399 /* Check if key is private or public */ 400 is_priv = 401 mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 && 402 mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 && 403 mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 && 404 mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 && 405 mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0; 406 407 if( !is_priv ) 408 { 409 /* If we're trying to export private parameters for a public key, 410 * something must be wrong. */ 411 if( P != NULL || Q != NULL || D != NULL ) 412 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 413 414 } 415 416 /* Export all requested core parameters. */ 417 418 if( ( N != NULL && ( ret = mbedtls_mpi_copy( N, &ctx->N ) ) != 0 ) || 419 ( P != NULL && ( ret = mbedtls_mpi_copy( P, &ctx->P ) ) != 0 ) || 420 ( Q != NULL && ( ret = mbedtls_mpi_copy( Q, &ctx->Q ) ) != 0 ) || 421 ( D != NULL && ( ret = mbedtls_mpi_copy( D, &ctx->D ) ) != 0 ) || 422 ( E != NULL && ( ret = mbedtls_mpi_copy( E, &ctx->E ) ) != 0 ) ) 423 { 424 return( ret ); 425 } 426 427 return( 0 ); 428 } 429 430 /* 431 * Export CRT parameters 432 * This must also be implemented if CRT is not used, for being able to 433 * write DER encoded RSA keys. The helper function mbedtls_rsa_deduce_crt 434 * can be used in this case. 435 */ 436 int mbedtls_rsa_export_crt( const mbedtls_rsa_context *ctx, 437 mbedtls_mpi *DP, mbedtls_mpi *DQ, mbedtls_mpi *QP ) 438 { 439 int ret; 440 int is_priv; 441 RSA_VALIDATE_RET( ctx != NULL ); 442 443 /* Check if key is private or public */ 444 is_priv = 445 mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 && 446 mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 && 447 mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 && 448 mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 && 449 mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0; 450 451 if( !is_priv ) 452 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 453 454 #if !defined(MBEDTLS_RSA_NO_CRT) 455 /* Export all requested blinding parameters. */ 456 if( ( DP != NULL && ( ret = mbedtls_mpi_copy( DP, &ctx->DP ) ) != 0 ) || 457 ( DQ != NULL && ( ret = mbedtls_mpi_copy( DQ, &ctx->DQ ) ) != 0 ) || 458 ( QP != NULL && ( ret = mbedtls_mpi_copy( QP, &ctx->QP ) ) != 0 ) ) 459 { 460 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 461 } 462 #else 463 if( ( ret = mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D, 464 DP, DQ, QP ) ) != 0 ) 465 { 466 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 467 } 468 #endif 469 470 return( 0 ); 471 } 472 473 /* 474 * Initialize an RSA context 475 */ 476 void mbedtls_rsa_init( mbedtls_rsa_context *ctx, 477 int padding, 478 int hash_id ) 479 { 480 RSA_VALIDATE( ctx != NULL ); 481 RSA_VALIDATE( padding == MBEDTLS_RSA_PKCS_V15 || 482 padding == MBEDTLS_RSA_PKCS_V21 ); 483 484 memset( ctx, 0, sizeof( mbedtls_rsa_context ) ); 485 486 mbedtls_rsa_set_padding( ctx, padding, hash_id ); 487 488 #if defined(MBEDTLS_THREADING_C) 489 mbedtls_mutex_init( &ctx->mutex ); 490 #endif 491 } 492 493 /* 494 * Set padding for an existing RSA context 495 */ 496 void mbedtls_rsa_set_padding( mbedtls_rsa_context *ctx, int padding, 497 int hash_id ) 498 { 499 RSA_VALIDATE( ctx != NULL ); 500 RSA_VALIDATE( padding == MBEDTLS_RSA_PKCS_V15 || 501 padding == MBEDTLS_RSA_PKCS_V21 ); 502 503 ctx->padding = padding; 504 ctx->hash_id = hash_id; 505 } 506 507 /* 508 * Get length in bytes of RSA modulus 509 */ 510 511 size_t mbedtls_rsa_get_len( const mbedtls_rsa_context *ctx ) 512 { 513 return( ctx->len ); 514 } 515 516 517 #if defined(MBEDTLS_GENPRIME) 518 519 /* 520 * Generate an RSA keypair 521 * 522 * This generation method follows the RSA key pair generation procedure of 523 * FIPS 186-4 if 2^16 < exponent < 2^256 and nbits = 2048 or nbits = 3072. 524 */ 525 int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx, 526 int (*f_rng)(void *, unsigned char *, size_t), 527 void *p_rng, 528 unsigned int nbits, int exponent ) 529 { 530 int ret; 531 mbedtls_mpi H, G, L; 532 int prime_quality = 0; 533 RSA_VALIDATE_RET( ctx != NULL ); 534 RSA_VALIDATE_RET( f_rng != NULL ); 535 536 if( nbits < 128 || exponent < 3 || nbits % 2 != 0 ) 537 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 538 539 /* 540 * If the modulus is 1024 bit long or shorter, then the security strength of 541 * the RSA algorithm is less than or equal to 80 bits and therefore an error 542 * rate of 2^-80 is sufficient. 543 */ 544 if( nbits > 1024 ) 545 prime_quality = MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR; 546 547 mbedtls_mpi_init( &H ); 548 mbedtls_mpi_init( &G ); 549 mbedtls_mpi_init( &L ); 550 551 /* 552 * find primes P and Q with Q < P so that: 553 * 1. |P-Q| > 2^( nbits / 2 - 100 ) 554 * 2. GCD( E, (P-1)*(Q-1) ) == 1 555 * 3. E^-1 mod LCM(P-1, Q-1) > 2^( nbits / 2 ) 556 */ 557 MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &ctx->E, exponent ) ); 558 559 do 560 { 561 MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, nbits >> 1, 562 prime_quality, f_rng, p_rng ) ); 563 564 MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1, 565 prime_quality, f_rng, p_rng ) ); 566 567 /* make sure the difference between p and q is not too small (FIPS 186-4 §B.3.3 step 5.4) */ 568 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &H, &ctx->P, &ctx->Q ) ); 569 if( mbedtls_mpi_bitlen( &H ) <= ( ( nbits >= 200 ) ? ( ( nbits >> 1 ) - 99 ) : 0 ) ) 570 continue; 571 572 /* not required by any standards, but some users rely on the fact that P > Q */ 573 if( H.s < 0 ) 574 mbedtls_mpi_swap( &ctx->P, &ctx->Q ); 575 576 /* Temporarily replace P,Q by P-1, Q-1 */ 577 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &ctx->P, &ctx->P, 1 ) ); 578 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &ctx->Q, &ctx->Q, 1 ) ); 579 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &ctx->P, &ctx->Q ) ); 580 581 /* check GCD( E, (P-1)*(Q-1) ) == 1 (FIPS 186-4 §B.3.1 criterion 2(a)) */ 582 MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->E, &H ) ); 583 if( mbedtls_mpi_cmp_int( &G, 1 ) != 0 ) 584 continue; 585 586 /* compute smallest possible D = E^-1 mod LCM(P-1, Q-1) (FIPS 186-4 §B.3.1 criterion 3(b)) */ 587 MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->P, &ctx->Q ) ); 588 MBEDTLS_MPI_CHK( mbedtls_mpi_div_mpi( &L, NULL, &H, &G ) ); 589 MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->D, &ctx->E, &L ) ); 590 591 if( mbedtls_mpi_bitlen( &ctx->D ) <= ( ( nbits + 1 ) / 2 ) ) // (FIPS 186-4 §B.3.1 criterion 3(a)) 592 continue; 593 594 break; 595 } 596 while( 1 ); 597 598 /* Restore P,Q */ 599 MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( &ctx->P, &ctx->P, 1 ) ); 600 MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( &ctx->Q, &ctx->Q, 1 ) ); 601 602 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) ); 603 604 ctx->len = mbedtls_mpi_size( &ctx->N ); 605 606 #if !defined(MBEDTLS_RSA_NO_CRT) 607 /* 608 * DP = D mod (P - 1) 609 * DQ = D mod (Q - 1) 610 * QP = Q^-1 mod P 611 */ 612 MBEDTLS_MPI_CHK( mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D, 613 &ctx->DP, &ctx->DQ, &ctx->QP ) ); 614 #endif /* MBEDTLS_RSA_NO_CRT */ 615 616 /* Double-check */ 617 MBEDTLS_MPI_CHK( mbedtls_rsa_check_privkey( ctx ) ); 618 619 cleanup: 620 621 mbedtls_mpi_free( &H ); 622 mbedtls_mpi_free( &G ); 623 mbedtls_mpi_free( &L ); 624 625 if( ret != 0 ) 626 { 627 mbedtls_rsa_free( ctx ); 628 return( MBEDTLS_ERR_RSA_KEY_GEN_FAILED + ret ); 629 } 630 631 return( 0 ); 632 } 633 634 #endif /* MBEDTLS_GENPRIME */ 635 636 /* 637 * Check a public RSA key 638 */ 639 int mbedtls_rsa_check_pubkey( const mbedtls_rsa_context *ctx ) 640 { 641 RSA_VALIDATE_RET( ctx != NULL ); 642 643 if( rsa_check_context( ctx, 0 /* public */, 0 /* no blinding */ ) != 0 ) 644 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 645 646 if( mbedtls_mpi_bitlen( &ctx->N ) < 128 ) 647 { 648 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 649 } 650 651 if( mbedtls_mpi_get_bit( &ctx->E, 0 ) == 0 || 652 mbedtls_mpi_bitlen( &ctx->E ) < 2 || 653 mbedtls_mpi_cmp_mpi( &ctx->E, &ctx->N ) >= 0 ) 654 { 655 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 656 } 657 658 return( 0 ); 659 } 660 661 /* 662 * Check for the consistency of all fields in an RSA private key context 663 */ 664 int mbedtls_rsa_check_privkey( const mbedtls_rsa_context *ctx ) 665 { 666 RSA_VALIDATE_RET( ctx != NULL ); 667 668 if( mbedtls_rsa_check_pubkey( ctx ) != 0 || 669 rsa_check_context( ctx, 1 /* private */, 1 /* blinding */ ) != 0 ) 670 { 671 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 672 } 673 674 if( mbedtls_rsa_validate_params( &ctx->N, &ctx->P, &ctx->Q, 675 &ctx->D, &ctx->E, NULL, NULL ) != 0 ) 676 { 677 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 678 } 679 680 #if !defined(MBEDTLS_RSA_NO_CRT) 681 else if( mbedtls_rsa_validate_crt( &ctx->P, &ctx->Q, &ctx->D, 682 &ctx->DP, &ctx->DQ, &ctx->QP ) != 0 ) 683 { 684 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 685 } 686 #endif 687 688 return( 0 ); 689 } 690 691 /* 692 * Check if contexts holding a public and private key match 693 */ 694 int mbedtls_rsa_check_pub_priv( const mbedtls_rsa_context *pub, 695 const mbedtls_rsa_context *prv ) 696 { 697 RSA_VALIDATE_RET( pub != NULL ); 698 RSA_VALIDATE_RET( prv != NULL ); 699 700 if( mbedtls_rsa_check_pubkey( pub ) != 0 || 701 mbedtls_rsa_check_privkey( prv ) != 0 ) 702 { 703 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 704 } 705 706 if( mbedtls_mpi_cmp_mpi( &pub->N, &prv->N ) != 0 || 707 mbedtls_mpi_cmp_mpi( &pub->E, &prv->E ) != 0 ) 708 { 709 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 710 } 711 712 return( 0 ); 713 } 714 715 /* 716 * Do an RSA public key operation 717 */ 718 int mbedtls_rsa_public( mbedtls_rsa_context *ctx, 719 const unsigned char *input, 720 unsigned char *output ) 721 { 722 int ret; 723 size_t olen; 724 mbedtls_mpi T; 725 RSA_VALIDATE_RET( ctx != NULL ); 726 RSA_VALIDATE_RET( input != NULL ); 727 RSA_VALIDATE_RET( output != NULL ); 728 729 if( rsa_check_context( ctx, 0 /* public */, 0 /* no blinding */ ) ) 730 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 731 732 mbedtls_mpi_init( &T ); 733 734 #if defined(MBEDTLS_THREADING_C) 735 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) 736 return( ret ); 737 #endif 738 739 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) ); 740 741 if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 ) 742 { 743 ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA; 744 goto cleanup; 745 } 746 747 olen = ctx->len; 748 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, &ctx->E, &ctx->N, &ctx->RN ) ); 749 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) ); 750 751 cleanup: 752 #if defined(MBEDTLS_THREADING_C) 753 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) 754 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); 755 #endif 756 757 mbedtls_mpi_free( &T ); 758 759 if( ret != 0 ) 760 return( MBEDTLS_ERR_RSA_PUBLIC_FAILED + ret ); 761 762 return( 0 ); 763 } 764 765 /* 766 * Generate or update blinding values, see section 10 of: 767 * KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA, 768 * DSS, and other systems. In : Advances in Cryptology-CRYPTO'96. Springer 769 * Berlin Heidelberg, 1996. p. 104-113. 770 */ 771 static int rsa_prepare_blinding( mbedtls_rsa_context *ctx, 772 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) 773 { 774 int ret, count = 0; 775 776 if( ctx->Vf.p != NULL ) 777 { 778 /* We already have blinding values, just update them by squaring */ 779 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &ctx->Vi ) ); 780 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) ); 781 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, &ctx->Vf ) ); 782 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->N ) ); 783 784 goto cleanup; 785 } 786 787 /* Unblinding value: Vf = random number, invertible mod N */ 788 do { 789 if( count++ > 10 ) 790 return( MBEDTLS_ERR_RSA_RNG_FAILED ); 791 792 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->Vf, ctx->len - 1, f_rng, p_rng ) ); 793 MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &ctx->Vi, &ctx->Vf, &ctx->N ) ); 794 } while( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) != 0 ); 795 796 /* Blinding value: Vi = Vf^(-e) mod N */ 797 MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vi, &ctx->Vf, &ctx->N ) ); 798 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->Vi, &ctx->Vi, &ctx->E, &ctx->N, &ctx->RN ) ); 799 800 801 cleanup: 802 return( ret ); 803 } 804 805 /* 806 * Exponent blinding supposed to prevent side-channel attacks using multiple 807 * traces of measurements to recover the RSA key. The more collisions are there, 808 * the more bits of the key can be recovered. See [3]. 809 * 810 * Collecting n collisions with m bit long blinding value requires 2^(m-m/n) 811 * observations on avarage. 812 * 813 * For example with 28 byte blinding to achieve 2 collisions the adversary has 814 * to make 2^112 observations on avarage. 815 * 816 * (With the currently (as of 2017 April) known best algorithms breaking 2048 817 * bit RSA requires approximately as much time as trying out 2^112 random keys. 818 * Thus in this sense with 28 byte blinding the security is not reduced by 819 * side-channel attacks like the one in [3]) 820 * 821 * This countermeasure does not help if the key recovery is possible with a 822 * single trace. 823 */ 824 #define RSA_EXPONENT_BLINDING 28 825 826 /* 827 * Do an RSA private key operation 828 */ 829 int mbedtls_rsa_private( mbedtls_rsa_context *ctx, 830 int (*f_rng)(void *, unsigned char *, size_t), 831 void *p_rng, 832 const unsigned char *input, 833 unsigned char *output ) 834 { 835 int ret; 836 size_t olen; 837 838 /* Temporary holding the result */ 839 mbedtls_mpi T; 840 841 /* Temporaries holding P-1, Q-1 and the 842 * exponent blinding factor, respectively. */ 843 mbedtls_mpi P1, Q1, R; 844 845 #if !defined(MBEDTLS_RSA_NO_CRT) 846 /* Temporaries holding the results mod p resp. mod q. */ 847 mbedtls_mpi TP, TQ; 848 849 /* Temporaries holding the blinded exponents for 850 * the mod p resp. mod q computation (if used). */ 851 mbedtls_mpi DP_blind, DQ_blind; 852 853 /* Pointers to actual exponents to be used - either the unblinded 854 * or the blinded ones, depending on the presence of a PRNG. */ 855 mbedtls_mpi *DP = &ctx->DP; 856 mbedtls_mpi *DQ = &ctx->DQ; 857 #else 858 /* Temporary holding the blinded exponent (if used). */ 859 mbedtls_mpi D_blind; 860 861 /* Pointer to actual exponent to be used - either the unblinded 862 * or the blinded one, depending on the presence of a PRNG. */ 863 mbedtls_mpi *D = &ctx->D; 864 #endif /* MBEDTLS_RSA_NO_CRT */ 865 866 /* Temporaries holding the initial input and the double 867 * checked result; should be the same in the end. */ 868 mbedtls_mpi I, C; 869 870 RSA_VALIDATE_RET( ctx != NULL ); 871 RSA_VALIDATE_RET( input != NULL ); 872 RSA_VALIDATE_RET( output != NULL ); 873 874 if( rsa_check_context( ctx, 1 /* private key checks */, 875 f_rng != NULL /* blinding y/n */ ) != 0 ) 876 { 877 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 878 } 879 880 #if defined(MBEDTLS_THREADING_C) 881 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) 882 return( ret ); 883 #endif 884 885 /* MPI Initialization */ 886 mbedtls_mpi_init( &T ); 887 888 mbedtls_mpi_init( &P1 ); 889 mbedtls_mpi_init( &Q1 ); 890 mbedtls_mpi_init( &R ); 891 892 if( f_rng != NULL ) 893 { 894 #if defined(MBEDTLS_RSA_NO_CRT) 895 mbedtls_mpi_init( &D_blind ); 896 #else 897 mbedtls_mpi_init( &DP_blind ); 898 mbedtls_mpi_init( &DQ_blind ); 899 #endif 900 } 901 902 #if !defined(MBEDTLS_RSA_NO_CRT) 903 mbedtls_mpi_init( &TP ); mbedtls_mpi_init( &TQ ); 904 #endif 905 906 mbedtls_mpi_init( &I ); 907 mbedtls_mpi_init( &C ); 908 909 /* End of MPI initialization */ 910 911 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) ); 912 if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 ) 913 { 914 ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA; 915 goto cleanup; 916 } 917 918 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &I, &T ) ); 919 920 if( f_rng != NULL ) 921 { 922 /* 923 * Blinding 924 * T = T * Vi mod N 925 */ 926 MBEDTLS_MPI_CHK( rsa_prepare_blinding( ctx, f_rng, p_rng ) ); 927 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vi ) ); 928 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) ); 929 930 /* 931 * Exponent blinding 932 */ 933 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) ); 934 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) ); 935 936 #if defined(MBEDTLS_RSA_NO_CRT) 937 /* 938 * D_blind = ( P - 1 ) * ( Q - 1 ) * R + D 939 */ 940 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING, 941 f_rng, p_rng ) ); 942 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &D_blind, &P1, &Q1 ) ); 943 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &D_blind, &D_blind, &R ) ); 944 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &D_blind, &D_blind, &ctx->D ) ); 945 946 D = &D_blind; 947 #else 948 /* 949 * DP_blind = ( P - 1 ) * R + DP 950 */ 951 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING, 952 f_rng, p_rng ) ); 953 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DP_blind, &P1, &R ) ); 954 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &DP_blind, &DP_blind, 955 &ctx->DP ) ); 956 957 DP = &DP_blind; 958 959 /* 960 * DQ_blind = ( Q - 1 ) * R + DQ 961 */ 962 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING, 963 f_rng, p_rng ) ); 964 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DQ_blind, &Q1, &R ) ); 965 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &DQ_blind, &DQ_blind, 966 &ctx->DQ ) ); 967 968 DQ = &DQ_blind; 969 #endif /* MBEDTLS_RSA_NO_CRT */ 970 } 971 972 #if defined(MBEDTLS_RSA_NO_CRT) 973 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, D, &ctx->N, &ctx->RN ) ); 974 #else 975 /* 976 * Faster decryption using the CRT 977 * 978 * TP = input ^ dP mod P 979 * TQ = input ^ dQ mod Q 980 */ 981 982 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &TP, &T, DP, &ctx->P, &ctx->RP ) ); 983 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &TQ, &T, DQ, &ctx->Q, &ctx->RQ ) ); 984 985 /* 986 * T = (TP - TQ) * (Q^-1 mod P) mod P 987 */ 988 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &T, &TP, &TQ ) ); 989 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &TP, &T, &ctx->QP ) ); 990 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &TP, &ctx->P ) ); 991 992 /* 993 * T = TQ + T * Q 994 */ 995 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &TP, &T, &ctx->Q ) ); 996 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &TQ, &TP ) ); 997 #endif /* MBEDTLS_RSA_NO_CRT */ 998 999 if( f_rng != NULL ) 1000 { 1001 /* 1002 * Unblind 1003 * T = T * Vf mod N 1004 */ 1005 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vf ) ); 1006 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) ); 1007 } 1008 1009 /* Verify the result to prevent glitching attacks. */ 1010 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &C, &T, &ctx->E, 1011 &ctx->N, &ctx->RN ) ); 1012 if( mbedtls_mpi_cmp_mpi( &C, &I ) != 0 ) 1013 { 1014 ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; 1015 goto cleanup; 1016 } 1017 1018 olen = ctx->len; 1019 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) ); 1020 1021 cleanup: 1022 #if defined(MBEDTLS_THREADING_C) 1023 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) 1024 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); 1025 #endif 1026 1027 mbedtls_mpi_free( &P1 ); 1028 mbedtls_mpi_free( &Q1 ); 1029 mbedtls_mpi_free( &R ); 1030 1031 if( f_rng != NULL ) 1032 { 1033 #if defined(MBEDTLS_RSA_NO_CRT) 1034 mbedtls_mpi_free( &D_blind ); 1035 #else 1036 mbedtls_mpi_free( &DP_blind ); 1037 mbedtls_mpi_free( &DQ_blind ); 1038 #endif 1039 } 1040 1041 mbedtls_mpi_free( &T ); 1042 1043 #if !defined(MBEDTLS_RSA_NO_CRT) 1044 mbedtls_mpi_free( &TP ); mbedtls_mpi_free( &TQ ); 1045 #endif 1046 1047 mbedtls_mpi_free( &C ); 1048 mbedtls_mpi_free( &I ); 1049 1050 if( ret != 0 ) 1051 return( MBEDTLS_ERR_RSA_PRIVATE_FAILED + ret ); 1052 1053 return( 0 ); 1054 } 1055 1056 #if defined(MBEDTLS_PKCS1_V21) 1057 /** 1058 * Generate and apply the MGF1 operation (from PKCS#1 v2.1) to a buffer. 1059 * 1060 * \param dst buffer to mask 1061 * \param dlen length of destination buffer 1062 * \param src source of the mask generation 1063 * \param slen length of the source buffer 1064 * \param md_ctx message digest context to use 1065 */ 1066 static int mgf_mask( unsigned char *dst, size_t dlen, unsigned char *src, 1067 size_t slen, mbedtls_md_context_t *md_ctx ) 1068 { 1069 unsigned char mask[MBEDTLS_MD_MAX_SIZE]; 1070 unsigned char counter[4]; 1071 unsigned char *p; 1072 unsigned int hlen; 1073 size_t i, use_len; 1074 int ret = 0; 1075 1076 memset( mask, 0, MBEDTLS_MD_MAX_SIZE ); 1077 memset( counter, 0, 4 ); 1078 1079 hlen = mbedtls_md_get_size( md_ctx->md_info ); 1080 1081 /* Generate and apply dbMask */ 1082 p = dst; 1083 1084 while( dlen > 0 ) 1085 { 1086 use_len = hlen; 1087 if( dlen < hlen ) 1088 use_len = dlen; 1089 1090 if( ( ret = mbedtls_md_starts( md_ctx ) ) != 0 ) 1091 goto exit; 1092 if( ( ret = mbedtls_md_update( md_ctx, src, slen ) ) != 0 ) 1093 goto exit; 1094 if( ( ret = mbedtls_md_update( md_ctx, counter, 4 ) ) != 0 ) 1095 goto exit; 1096 if( ( ret = mbedtls_md_finish( md_ctx, mask ) ) != 0 ) 1097 goto exit; 1098 1099 for( i = 0; i < use_len; ++i ) 1100 *p++ ^= mask[i]; 1101 1102 counter[3]++; 1103 1104 dlen -= use_len; 1105 } 1106 1107 exit: 1108 mbedtls_platform_zeroize( mask, sizeof( mask ) ); 1109 1110 return( ret ); 1111 } 1112 #endif /* MBEDTLS_PKCS1_V21 */ 1113 1114 #if defined(MBEDTLS_PKCS1_V21) 1115 /* 1116 * Implementation of the PKCS#1 v2.1 RSAES-OAEP-ENCRYPT function 1117 */ 1118 int mbedtls_rsa_rsaes_oaep_encrypt( mbedtls_rsa_context *ctx, 1119 int (*f_rng)(void *, unsigned char *, size_t), 1120 void *p_rng, 1121 int mode, 1122 const unsigned char *label, size_t label_len, 1123 size_t ilen, 1124 const unsigned char *input, 1125 unsigned char *output ) 1126 { 1127 size_t olen; 1128 int ret; 1129 unsigned char *p = output; 1130 unsigned int hlen; 1131 const mbedtls_md_info_t *md_info; 1132 mbedtls_md_context_t md_ctx; 1133 1134 RSA_VALIDATE_RET( ctx != NULL ); 1135 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1136 mode == MBEDTLS_RSA_PUBLIC ); 1137 RSA_VALIDATE_RET( output != NULL ); 1138 RSA_VALIDATE_RET( input != NULL ); 1139 RSA_VALIDATE_RET( label_len == 0 || label != NULL ); 1140 1141 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) 1142 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1143 1144 if( f_rng == NULL ) 1145 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1146 1147 md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id ); 1148 if( md_info == NULL ) 1149 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1150 1151 olen = ctx->len; 1152 hlen = mbedtls_md_get_size( md_info ); 1153 1154 /* first comparison checks for overflow */ 1155 if( ilen + 2 * hlen + 2 < ilen || olen < ilen + 2 * hlen + 2 ) 1156 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1157 1158 memset( output, 0, olen ); 1159 1160 *p++ = 0; 1161 1162 /* Generate a random octet string seed */ 1163 if( ( ret = f_rng( p_rng, p, hlen ) ) != 0 ) 1164 return( MBEDTLS_ERR_RSA_RNG_FAILED + ret ); 1165 1166 p += hlen; 1167 1168 /* Construct DB */ 1169 if( ( ret = mbedtls_md( md_info, label, label_len, p ) ) != 0 ) 1170 return( ret ); 1171 p += hlen; 1172 p += olen - 2 * hlen - 2 - ilen; 1173 *p++ = 1; 1174 memcpy( p, input, ilen ); 1175 1176 mbedtls_md_init( &md_ctx ); 1177 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 1178 goto exit; 1179 1180 /* maskedDB: Apply dbMask to DB */ 1181 if( ( ret = mgf_mask( output + hlen + 1, olen - hlen - 1, output + 1, hlen, 1182 &md_ctx ) ) != 0 ) 1183 goto exit; 1184 1185 /* maskedSeed: Apply seedMask to seed */ 1186 if( ( ret = mgf_mask( output + 1, hlen, output + hlen + 1, olen - hlen - 1, 1187 &md_ctx ) ) != 0 ) 1188 goto exit; 1189 1190 exit: 1191 mbedtls_md_free( &md_ctx ); 1192 1193 if( ret != 0 ) 1194 return( ret ); 1195 1196 return( ( mode == MBEDTLS_RSA_PUBLIC ) 1197 ? mbedtls_rsa_public( ctx, output, output ) 1198 : mbedtls_rsa_private( ctx, f_rng, p_rng, output, output ) ); 1199 } 1200 #endif /* MBEDTLS_PKCS1_V21 */ 1201 1202 #if defined(MBEDTLS_PKCS1_V15) 1203 /* 1204 * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-ENCRYPT function 1205 */ 1206 int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx, 1207 int (*f_rng)(void *, unsigned char *, size_t), 1208 void *p_rng, 1209 int mode, size_t ilen, 1210 const unsigned char *input, 1211 unsigned char *output ) 1212 { 1213 size_t nb_pad, olen; 1214 int ret; 1215 unsigned char *p = output; 1216 1217 RSA_VALIDATE_RET( ctx != NULL ); 1218 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1219 mode == MBEDTLS_RSA_PUBLIC ); 1220 RSA_VALIDATE_RET( output != NULL ); 1221 RSA_VALIDATE_RET( input != NULL ); 1222 1223 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 1224 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1225 1226 olen = ctx->len; 1227 1228 /* first comparison checks for overflow */ 1229 if( ilen + 11 < ilen || olen < ilen + 11 ) 1230 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1231 1232 nb_pad = olen - 3 - ilen; 1233 1234 *p++ = 0; 1235 if( mode == MBEDTLS_RSA_PUBLIC ) 1236 { 1237 if( f_rng == NULL ) 1238 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1239 1240 *p++ = MBEDTLS_RSA_CRYPT; 1241 1242 while( nb_pad-- > 0 ) 1243 { 1244 int rng_dl = 100; 1245 1246 do { 1247 ret = f_rng( p_rng, p, 1 ); 1248 } while( *p == 0 && --rng_dl && ret == 0 ); 1249 1250 /* Check if RNG failed to generate data */ 1251 if( rng_dl == 0 || ret != 0 ) 1252 return( MBEDTLS_ERR_RSA_RNG_FAILED + ret ); 1253 1254 p++; 1255 } 1256 } 1257 else 1258 { 1259 *p++ = MBEDTLS_RSA_SIGN; 1260 1261 while( nb_pad-- > 0 ) 1262 *p++ = 0xFF; 1263 } 1264 1265 *p++ = 0; 1266 memcpy( p, input, ilen ); 1267 1268 return( ( mode == MBEDTLS_RSA_PUBLIC ) 1269 ? mbedtls_rsa_public( ctx, output, output ) 1270 : mbedtls_rsa_private( ctx, f_rng, p_rng, output, output ) ); 1271 } 1272 #endif /* MBEDTLS_PKCS1_V15 */ 1273 1274 /* 1275 * Add the message padding, then do an RSA operation 1276 */ 1277 int mbedtls_rsa_pkcs1_encrypt( mbedtls_rsa_context *ctx, 1278 int (*f_rng)(void *, unsigned char *, size_t), 1279 void *p_rng, 1280 int mode, size_t ilen, 1281 const unsigned char *input, 1282 unsigned char *output ) 1283 { 1284 RSA_VALIDATE_RET( ctx != NULL ); 1285 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1286 mode == MBEDTLS_RSA_PUBLIC ); 1287 RSA_VALIDATE_RET( output != NULL ); 1288 RSA_VALIDATE_RET( input != NULL ); 1289 1290 switch( ctx->padding ) 1291 { 1292 #if defined(MBEDTLS_PKCS1_V15) 1293 case MBEDTLS_RSA_PKCS_V15: 1294 return mbedtls_rsa_rsaes_pkcs1_v15_encrypt( ctx, f_rng, p_rng, mode, ilen, 1295 input, output ); 1296 #endif 1297 1298 #if defined(MBEDTLS_PKCS1_V21) 1299 case MBEDTLS_RSA_PKCS_V21: 1300 return mbedtls_rsa_rsaes_oaep_encrypt( ctx, f_rng, p_rng, mode, NULL, 0, 1301 ilen, input, output ); 1302 #endif 1303 1304 default: 1305 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 1306 } 1307 } 1308 1309 #if defined(MBEDTLS_PKCS1_V21) 1310 /* 1311 * Implementation of the PKCS#1 v2.1 RSAES-OAEP-DECRYPT function 1312 */ 1313 int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx, 1314 int (*f_rng)(void *, unsigned char *, size_t), 1315 void *p_rng, 1316 int mode, 1317 const unsigned char *label, size_t label_len, 1318 size_t *olen, 1319 const unsigned char *input, 1320 unsigned char *output, 1321 size_t output_max_len ) 1322 { 1323 int ret; 1324 size_t ilen, i, pad_len; 1325 unsigned char *p, bad, pad_done; 1326 unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; 1327 unsigned char lhash[MBEDTLS_MD_MAX_SIZE]; 1328 unsigned int hlen; 1329 const mbedtls_md_info_t *md_info; 1330 mbedtls_md_context_t md_ctx; 1331 1332 RSA_VALIDATE_RET( ctx != NULL ); 1333 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1334 mode == MBEDTLS_RSA_PUBLIC ); 1335 RSA_VALIDATE_RET( output_max_len == 0 || output != NULL ); 1336 RSA_VALIDATE_RET( label_len == 0 || label != NULL ); 1337 RSA_VALIDATE_RET( input != NULL ); 1338 RSA_VALIDATE_RET( olen != NULL ); 1339 1340 /* 1341 * Parameters sanity checks 1342 */ 1343 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) 1344 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1345 1346 ilen = ctx->len; 1347 1348 if( ilen < 16 || ilen > sizeof( buf ) ) 1349 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1350 1351 md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id ); 1352 if( md_info == NULL ) 1353 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1354 1355 hlen = mbedtls_md_get_size( md_info ); 1356 1357 // checking for integer underflow 1358 if( 2 * hlen + 2 > ilen ) 1359 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1360 1361 /* 1362 * RSA operation 1363 */ 1364 if( ctx->P.n == 0 ) 1365 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 1366 ? mbedtls_rsa_public( ctx, input, buf ) 1367 : mbedtls_rsa_private( ctx, NULL, NULL, input, buf ); 1368 else 1369 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 1370 ? mbedtls_rsa_public( ctx, input, buf ) 1371 : mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf ); 1372 1373 if( ret != 0 ) 1374 goto cleanup; 1375 1376 /* 1377 * Unmask data and generate lHash 1378 */ 1379 mbedtls_md_init( &md_ctx ); 1380 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 1381 { 1382 mbedtls_md_free( &md_ctx ); 1383 goto cleanup; 1384 } 1385 1386 /* seed: Apply seedMask to maskedSeed */ 1387 if( ( ret = mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1, 1388 &md_ctx ) ) != 0 || 1389 /* DB: Apply dbMask to maskedDB */ 1390 ( ret = mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen, 1391 &md_ctx ) ) != 0 ) 1392 { 1393 mbedtls_md_free( &md_ctx ); 1394 goto cleanup; 1395 } 1396 1397 mbedtls_md_free( &md_ctx ); 1398 1399 /* Generate lHash */ 1400 if( ( ret = mbedtls_md( md_info, label, label_len, lhash ) ) != 0 ) 1401 goto cleanup; 1402 1403 /* 1404 * Check contents, in "constant-time" 1405 */ 1406 p = buf; 1407 bad = 0; 1408 1409 bad |= *p++; /* First byte must be 0 */ 1410 1411 p += hlen; /* Skip seed */ 1412 1413 /* Check lHash */ 1414 for( i = 0; i < hlen; i++ ) 1415 bad |= lhash[i] ^ *p++; 1416 1417 /* Get zero-padding len, but always read till end of buffer 1418 * (minus one, for the 01 byte) */ 1419 pad_len = 0; 1420 pad_done = 0; 1421 for( i = 0; i < ilen - 2 * hlen - 2; i++ ) 1422 { 1423 pad_done |= p[i]; 1424 pad_len += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1; 1425 } 1426 1427 p += pad_len; 1428 bad |= *p++ ^ 0x01; 1429 1430 /* 1431 * The only information "leaked" is whether the padding was correct or not 1432 * (eg, no data is copied if it was not correct). This meets the 1433 * recommendations in PKCS#1 v2.2: an opponent cannot distinguish between 1434 * the different error conditions. 1435 */ 1436 if( bad != 0 ) 1437 { 1438 ret = MBEDTLS_ERR_RSA_INVALID_PADDING; 1439 goto cleanup; 1440 } 1441 1442 if( ilen - ( p - buf ) > output_max_len ) 1443 { 1444 ret = MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE; 1445 goto cleanup; 1446 } 1447 1448 *olen = ilen - (p - buf); 1449 memcpy( output, p, *olen ); 1450 ret = 0; 1451 1452 cleanup: 1453 mbedtls_platform_zeroize( buf, sizeof( buf ) ); 1454 mbedtls_platform_zeroize( lhash, sizeof( lhash ) ); 1455 1456 return( ret ); 1457 } 1458 #endif /* MBEDTLS_PKCS1_V21 */ 1459 1460 #if defined(MBEDTLS_PKCS1_V15) 1461 /** Turn zero-or-nonzero into zero-or-all-bits-one, without branches. 1462 * 1463 * \param value The value to analyze. 1464 * \return Zero if \p value is zero, otherwise all-bits-one. 1465 */ 1466 static unsigned all_or_nothing_int( unsigned value ) 1467 { 1468 /* MSVC has a warning about unary minus on unsigned, but this is 1469 * well-defined and precisely what we want to do here */ 1470 #if defined(_MSC_VER) 1471 #pragma warning( push ) 1472 #pragma warning( disable : 4146 ) 1473 #endif 1474 return( - ( ( value | - value ) >> ( sizeof( value ) * 8 - 1 ) ) ); 1475 #if defined(_MSC_VER) 1476 #pragma warning( pop ) 1477 #endif 1478 } 1479 1480 /** Check whether a size is out of bounds, without branches. 1481 * 1482 * This is equivalent to `size > max`, but is likely to be compiled to 1483 * to code using bitwise operation rather than a branch. 1484 * 1485 * \param size Size to check. 1486 * \param max Maximum desired value for \p size. 1487 * \return \c 0 if `size <= max`. 1488 * \return \c 1 if `size > max`. 1489 */ 1490 static unsigned size_greater_than( size_t size, size_t max ) 1491 { 1492 /* Return the sign bit (1 for negative) of (max - size). */ 1493 return( ( max - size ) >> ( sizeof( size_t ) * 8 - 1 ) ); 1494 } 1495 1496 /** Choose between two integer values, without branches. 1497 * 1498 * This is equivalent to `cond ? if1 : if0`, but is likely to be compiled 1499 * to code using bitwise operation rather than a branch. 1500 * 1501 * \param cond Condition to test. 1502 * \param if1 Value to use if \p cond is nonzero. 1503 * \param if0 Value to use if \p cond is zero. 1504 * \return \c if1 if \p cond is nonzero, otherwise \c if0. 1505 */ 1506 static unsigned if_int( unsigned cond, unsigned if1, unsigned if0 ) 1507 { 1508 unsigned mask = all_or_nothing_int( cond ); 1509 return( ( mask & if1 ) | (~mask & if0 ) ); 1510 } 1511 1512 /** Shift some data towards the left inside a buffer without leaking 1513 * the length of the data through side channels. 1514 * 1515 * `mem_move_to_left(start, total, offset)` is functionally equivalent to 1516 * ``` 1517 * memmove(start, start + offset, total - offset); 1518 * memset(start + offset, 0, total - offset); 1519 * ``` 1520 * but it strives to use a memory access pattern (and thus total timing) 1521 * that does not depend on \p offset. This timing independence comes at 1522 * the expense of performance. 1523 * 1524 * \param start Pointer to the start of the buffer. 1525 * \param total Total size of the buffer. 1526 * \param offset Offset from which to copy \p total - \p offset bytes. 1527 */ 1528 static void mem_move_to_left( void *start, 1529 size_t total, 1530 size_t offset ) 1531 { 1532 volatile unsigned char *buf = start; 1533 size_t i, n; 1534 if( total == 0 ) 1535 return; 1536 for( i = 0; i < total; i++ ) 1537 { 1538 unsigned no_op = size_greater_than( total - offset, i ); 1539 /* The first `total - offset` passes are a no-op. The last 1540 * `offset` passes shift the data one byte to the left and 1541 * zero out the last byte. */ 1542 for( n = 0; n < total - 1; n++ ) 1543 { 1544 unsigned char current = buf[n]; 1545 unsigned char next = buf[n+1]; 1546 buf[n] = if_int( no_op, current, next ); 1547 } 1548 buf[total-1] = if_int( no_op, buf[total-1], 0 ); 1549 } 1550 } 1551 1552 /* 1553 * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-DECRYPT function 1554 */ 1555 int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx, 1556 int (*f_rng)(void *, unsigned char *, size_t), 1557 void *p_rng, 1558 int mode, size_t *olen, 1559 const unsigned char *input, 1560 unsigned char *output, 1561 size_t output_max_len ) 1562 { 1563 int ret; 1564 size_t ilen, i, plaintext_max_size; 1565 unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; 1566 /* The following variables take sensitive values: their value must 1567 * not leak into the observable behavior of the function other than 1568 * the designated outputs (output, olen, return value). Otherwise 1569 * this would open the execution of the function to 1570 * side-channel-based variants of the Bleichenbacher padding oracle 1571 * attack. Potential side channels include overall timing, memory 1572 * access patterns (especially visible to an adversary who has access 1573 * to a shared memory cache), and branches (especially visible to 1574 * an adversary who has access to a shared code cache or to a shared 1575 * branch predictor). */ 1576 size_t pad_count = 0; 1577 unsigned bad = 0; 1578 unsigned char pad_done = 0; 1579 size_t plaintext_size = 0; 1580 unsigned output_too_large; 1581 1582 RSA_VALIDATE_RET( ctx != NULL ); 1583 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1584 mode == MBEDTLS_RSA_PUBLIC ); 1585 RSA_VALIDATE_RET( output_max_len == 0 || output != NULL ); 1586 RSA_VALIDATE_RET( input != NULL ); 1587 RSA_VALIDATE_RET( olen != NULL ); 1588 1589 ilen = ctx->len; 1590 plaintext_max_size = ( output_max_len > ilen - 11 ? 1591 ilen - 11 : 1592 output_max_len ); 1593 1594 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 1595 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1596 1597 if( ilen < 16 || ilen > sizeof( buf ) ) 1598 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1599 1600 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 1601 ? mbedtls_rsa_public( ctx, input, buf ) 1602 : mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf ); 1603 1604 if( ret != 0 ) 1605 goto cleanup; 1606 1607 /* Check and get padding length in constant time and constant 1608 * memory trace. The first byte must be 0. */ 1609 bad |= buf[0]; 1610 1611 if( mode == MBEDTLS_RSA_PRIVATE ) 1612 { 1613 /* Decode EME-PKCS1-v1_5 padding: 0x00 || 0x02 || PS || 0x00 1614 * where PS must be at least 8 nonzero bytes. */ 1615 bad |= buf[1] ^ MBEDTLS_RSA_CRYPT; 1616 1617 /* Read the whole buffer. Set pad_done to nonzero if we find 1618 * the 0x00 byte and remember the padding length in pad_count. */ 1619 for( i = 2; i < ilen; i++ ) 1620 { 1621 pad_done |= ((buf[i] | (unsigned char)-buf[i]) >> 7) ^ 1; 1622 pad_count += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1; 1623 } 1624 } 1625 else 1626 { 1627 /* Decode EMSA-PKCS1-v1_5 padding: 0x00 || 0x01 || PS || 0x00 1628 * where PS must be at least 8 bytes with the value 0xFF. */ 1629 bad |= buf[1] ^ MBEDTLS_RSA_SIGN; 1630 1631 /* Read the whole buffer. Set pad_done to nonzero if we find 1632 * the 0x00 byte and remember the padding length in pad_count. 1633 * If there's a non-0xff byte in the padding, the padding is bad. */ 1634 for( i = 2; i < ilen; i++ ) 1635 { 1636 pad_done |= if_int( buf[i], 0, 1 ); 1637 pad_count += if_int( pad_done, 0, 1 ); 1638 bad |= if_int( pad_done, 0, buf[i] ^ 0xFF ); 1639 } 1640 } 1641 1642 /* If pad_done is still zero, there's no data, only unfinished padding. */ 1643 bad |= if_int( pad_done, 0, 1 ); 1644 1645 /* There must be at least 8 bytes of padding. */ 1646 bad |= size_greater_than( 8, pad_count ); 1647 1648 /* If the padding is valid, set plaintext_size to the number of 1649 * remaining bytes after stripping the padding. If the padding 1650 * is invalid, avoid leaking this fact through the size of the 1651 * output: use the maximum message size that fits in the output 1652 * buffer. Do it without branches to avoid leaking the padding 1653 * validity through timing. RSA keys are small enough that all the 1654 * size_t values involved fit in unsigned int. */ 1655 plaintext_size = if_int( bad, 1656 (unsigned) plaintext_max_size, 1657 (unsigned) ( ilen - pad_count - 3 ) ); 1658 1659 /* Set output_too_large to 0 if the plaintext fits in the output 1660 * buffer and to 1 otherwise. */ 1661 output_too_large = size_greater_than( plaintext_size, 1662 plaintext_max_size ); 1663 1664 /* Set ret without branches to avoid timing attacks. Return: 1665 * - INVALID_PADDING if the padding is bad (bad != 0). 1666 * - OUTPUT_TOO_LARGE if the padding is good but the decrypted 1667 * plaintext does not fit in the output buffer. 1668 * - 0 if the padding is correct. */ 1669 ret = - (int) if_int( bad, - MBEDTLS_ERR_RSA_INVALID_PADDING, 1670 if_int( output_too_large, - MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE, 1671 0 ) ); 1672 1673 /* If the padding is bad or the plaintext is too large, zero the 1674 * data that we're about to copy to the output buffer. 1675 * We need to copy the same amount of data 1676 * from the same buffer whether the padding is good or not to 1677 * avoid leaking the padding validity through overall timing or 1678 * through memory or cache access patterns. */ 1679 bad = all_or_nothing_int( bad | output_too_large ); 1680 for( i = 11; i < ilen; i++ ) 1681 buf[i] &= ~bad; 1682 1683 /* If the plaintext is too large, truncate it to the buffer size. 1684 * Copy anyway to avoid revealing the length through timing, because 1685 * revealing the length is as bad as revealing the padding validity 1686 * for a Bleichenbacher attack. */ 1687 plaintext_size = if_int( output_too_large, 1688 (unsigned) plaintext_max_size, 1689 (unsigned) plaintext_size ); 1690 1691 /* Move the plaintext to the leftmost position where it can start in 1692 * the working buffer, i.e. make it start plaintext_max_size from 1693 * the end of the buffer. Do this with a memory access trace that 1694 * does not depend on the plaintext size. After this move, the 1695 * starting location of the plaintext is no longer sensitive 1696 * information. */ 1697 mem_move_to_left( buf + ilen - plaintext_max_size, 1698 plaintext_max_size, 1699 plaintext_max_size - plaintext_size ); 1700 1701 /* Finally copy the decrypted plaintext plus trailing zeros 1702 * into the output buffer. */ 1703 memcpy( output, buf + ilen - plaintext_max_size, plaintext_max_size ); 1704 1705 /* Report the amount of data we copied to the output buffer. In case 1706 * of errors (bad padding or output too large), the value of *olen 1707 * when this function returns is not specified. Making it equivalent 1708 * to the good case limits the risks of leaking the padding validity. */ 1709 *olen = plaintext_size; 1710 1711 cleanup: 1712 mbedtls_platform_zeroize( buf, sizeof( buf ) ); 1713 1714 return( ret ); 1715 } 1716 #endif /* MBEDTLS_PKCS1_V15 */ 1717 1718 /* 1719 * Do an RSA operation, then remove the message padding 1720 */ 1721 int mbedtls_rsa_pkcs1_decrypt( mbedtls_rsa_context *ctx, 1722 int (*f_rng)(void *, unsigned char *, size_t), 1723 void *p_rng, 1724 int mode, size_t *olen, 1725 const unsigned char *input, 1726 unsigned char *output, 1727 size_t output_max_len) 1728 { 1729 RSA_VALIDATE_RET( ctx != NULL ); 1730 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1731 mode == MBEDTLS_RSA_PUBLIC ); 1732 RSA_VALIDATE_RET( output_max_len == 0 || output != NULL ); 1733 RSA_VALIDATE_RET( input != NULL ); 1734 RSA_VALIDATE_RET( olen != NULL ); 1735 1736 switch( ctx->padding ) 1737 { 1738 #if defined(MBEDTLS_PKCS1_V15) 1739 case MBEDTLS_RSA_PKCS_V15: 1740 return mbedtls_rsa_rsaes_pkcs1_v15_decrypt( ctx, f_rng, p_rng, mode, olen, 1741 input, output, output_max_len ); 1742 #endif 1743 1744 #if defined(MBEDTLS_PKCS1_V21) 1745 case MBEDTLS_RSA_PKCS_V21: 1746 return mbedtls_rsa_rsaes_oaep_decrypt( ctx, f_rng, p_rng, mode, NULL, 0, 1747 olen, input, output, 1748 output_max_len ); 1749 #endif 1750 1751 default: 1752 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 1753 } 1754 } 1755 1756 #if defined(MBEDTLS_PKCS1_V21) 1757 /* 1758 * Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function 1759 */ 1760 int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx, 1761 int (*f_rng)(void *, unsigned char *, size_t), 1762 void *p_rng, 1763 int mode, 1764 mbedtls_md_type_t md_alg, 1765 unsigned int hashlen, 1766 const unsigned char *hash, 1767 unsigned char *sig ) 1768 { 1769 size_t olen; 1770 unsigned char *p = sig; 1771 unsigned char salt[MBEDTLS_MD_MAX_SIZE]; 1772 size_t slen, min_slen, hlen, offset = 0; 1773 int ret; 1774 size_t msb; 1775 const mbedtls_md_info_t *md_info; 1776 mbedtls_md_context_t md_ctx; 1777 RSA_VALIDATE_RET( ctx != NULL ); 1778 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1779 mode == MBEDTLS_RSA_PUBLIC ); 1780 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 1781 hashlen == 0 ) || 1782 hash != NULL ); 1783 RSA_VALIDATE_RET( sig != NULL ); 1784 1785 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) 1786 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1787 1788 if( f_rng == NULL ) 1789 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1790 1791 olen = ctx->len; 1792 1793 if( md_alg != MBEDTLS_MD_NONE ) 1794 { 1795 /* Gather length of hash to sign */ 1796 md_info = mbedtls_md_info_from_type( md_alg ); 1797 if( md_info == NULL ) 1798 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1799 1800 hashlen = mbedtls_md_get_size( md_info ); 1801 } 1802 1803 md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id ); 1804 if( md_info == NULL ) 1805 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1806 1807 hlen = mbedtls_md_get_size( md_info ); 1808 1809 /* Calculate the largest possible salt length. Normally this is the hash 1810 * length, which is the maximum length the salt can have. If there is not 1811 * enough room, use the maximum salt length that fits. The constraint is 1812 * that the hash length plus the salt length plus 2 bytes must be at most 1813 * the key length. This complies with FIPS 186-4 §5.5 (e) and RFC 8017 1814 * (PKCS#1 v2.2) §9.1.1 step 3. */ 1815 min_slen = hlen - 2; 1816 if( olen < hlen + min_slen + 2 ) 1817 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1818 else if( olen >= hlen + hlen + 2 ) 1819 slen = hlen; 1820 else 1821 slen = olen - hlen - 2; 1822 1823 memset( sig, 0, olen ); 1824 1825 /* Generate salt of length slen */ 1826 if( ( ret = f_rng( p_rng, salt, slen ) ) != 0 ) 1827 return( MBEDTLS_ERR_RSA_RNG_FAILED + ret ); 1828 1829 /* Note: EMSA-PSS encoding is over the length of N - 1 bits */ 1830 msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; 1831 p += olen - hlen - slen - 2; 1832 *p++ = 0x01; 1833 memcpy( p, salt, slen ); 1834 p += slen; 1835 1836 mbedtls_md_init( &md_ctx ); 1837 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 1838 goto exit; 1839 1840 /* Generate H = Hash( M' ) */ 1841 if( ( ret = mbedtls_md_starts( &md_ctx ) ) != 0 ) 1842 goto exit; 1843 if( ( ret = mbedtls_md_update( &md_ctx, p, 8 ) ) != 0 ) 1844 goto exit; 1845 if( ( ret = mbedtls_md_update( &md_ctx, hash, hashlen ) ) != 0 ) 1846 goto exit; 1847 if( ( ret = mbedtls_md_update( &md_ctx, salt, slen ) ) != 0 ) 1848 goto exit; 1849 if( ( ret = mbedtls_md_finish( &md_ctx, p ) ) != 0 ) 1850 goto exit; 1851 1852 /* Compensate for boundary condition when applying mask */ 1853 if( msb % 8 == 0 ) 1854 offset = 1; 1855 1856 /* maskedDB: Apply dbMask to DB */ 1857 if( ( ret = mgf_mask( sig + offset, olen - hlen - 1 - offset, p, hlen, 1858 &md_ctx ) ) != 0 ) 1859 goto exit; 1860 1861 msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; 1862 sig[0] &= 0xFF >> ( olen * 8 - msb ); 1863 1864 p += hlen; 1865 *p++ = 0xBC; 1866 1867 mbedtls_platform_zeroize( salt, sizeof( salt ) ); 1868 1869 exit: 1870 mbedtls_md_free( &md_ctx ); 1871 1872 if( ret != 0 ) 1873 return( ret ); 1874 1875 if( ctx->P.n == 0) 1876 return( ( mode == MBEDTLS_RSA_PUBLIC ) 1877 ? mbedtls_rsa_public( ctx, sig, sig ) 1878 : mbedtls_rsa_private( ctx, NULL, NULL, sig, sig ) ); 1879 else 1880 return( ( mode == MBEDTLS_RSA_PUBLIC ) 1881 ? mbedtls_rsa_public( ctx, sig, sig ) 1882 : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig ) ); 1883 } 1884 #endif /* MBEDTLS_PKCS1_V21 */ 1885 1886 #if defined(MBEDTLS_PKCS1_V15) 1887 /* 1888 * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-V1_5-SIGN function 1889 */ 1890 1891 /* Construct a PKCS v1.5 encoding of a hashed message 1892 * 1893 * This is used both for signature generation and verification. 1894 * 1895 * Parameters: 1896 * - md_alg: Identifies the hash algorithm used to generate the given hash; 1897 * MBEDTLS_MD_NONE if raw data is signed. 1898 * - hashlen: Length of hash in case hashlen is MBEDTLS_MD_NONE. 1899 * - hash: Buffer containing the hashed message or the raw data. 1900 * - dst_len: Length of the encoded message. 1901 * - dst: Buffer to hold the encoded message. 1902 * 1903 * Assumptions: 1904 * - hash has size hashlen if md_alg == MBEDTLS_MD_NONE. 1905 * - hash has size corresponding to md_alg if md_alg != MBEDTLS_MD_NONE. 1906 * - dst points to a buffer of size at least dst_len. 1907 * 1908 */ 1909 static int rsa_rsassa_pkcs1_v15_encode( mbedtls_md_type_t md_alg, 1910 unsigned int hashlen, 1911 const unsigned char *hash, 1912 size_t dst_len, 1913 unsigned char *dst ) 1914 { 1915 size_t oid_size = 0; 1916 size_t nb_pad = dst_len; 1917 unsigned char *p = dst; 1918 const char *oid = NULL; 1919 1920 /* Are we signing hashed or raw data? */ 1921 if( md_alg != MBEDTLS_MD_NONE ) 1922 { 1923 const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg ); 1924 if( md_info == NULL ) 1925 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1926 1927 if( mbedtls_oid_get_oid_by_md( md_alg, &oid, &oid_size ) != 0 ) 1928 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1929 1930 hashlen = mbedtls_md_get_size( md_info ); 1931 1932 /* Double-check that 8 + hashlen + oid_size can be used as a 1933 * 1-byte ASN.1 length encoding and that there's no overflow. */ 1934 if( 8 + hashlen + oid_size >= 0x80 || 1935 10 + hashlen < hashlen || 1936 10 + hashlen + oid_size < 10 + hashlen ) 1937 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1938 1939 /* 1940 * Static bounds check: 1941 * - Need 10 bytes for five tag-length pairs. 1942 * (Insist on 1-byte length encodings to protect against variants of 1943 * Bleichenbacher's forgery attack against lax PKCS#1v1.5 verification) 1944 * - Need hashlen bytes for hash 1945 * - Need oid_size bytes for hash alg OID. 1946 */ 1947 if( nb_pad < 10 + hashlen + oid_size ) 1948 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1949 nb_pad -= 10 + hashlen + oid_size; 1950 } 1951 else 1952 { 1953 if( nb_pad < hashlen ) 1954 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1955 1956 nb_pad -= hashlen; 1957 } 1958 1959 /* Need space for signature header and padding delimiter (3 bytes), 1960 * and 8 bytes for the minimal padding */ 1961 if( nb_pad < 3 + 8 ) 1962 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1963 nb_pad -= 3; 1964 1965 /* Now nb_pad is the amount of memory to be filled 1966 * with padding, and at least 8 bytes long. */ 1967 1968 /* Write signature header and padding */ 1969 *p++ = 0; 1970 *p++ = MBEDTLS_RSA_SIGN; 1971 memset( p, 0xFF, nb_pad ); 1972 p += nb_pad; 1973 *p++ = 0; 1974 1975 /* Are we signing raw data? */ 1976 if( md_alg == MBEDTLS_MD_NONE ) 1977 { 1978 memcpy( p, hash, hashlen ); 1979 return( 0 ); 1980 } 1981 1982 /* Signing hashed data, add corresponding ASN.1 structure 1983 * 1984 * DigestInfo ::= SEQUENCE { 1985 * digestAlgorithm DigestAlgorithmIdentifier, 1986 * digest Digest } 1987 * DigestAlgorithmIdentifier ::= AlgorithmIdentifier 1988 * Digest ::= OCTET STRING 1989 * 1990 * Schematic: 1991 * TAG-SEQ + LEN [ TAG-SEQ + LEN [ TAG-OID + LEN [ OID ] 1992 * TAG-NULL + LEN [ NULL ] ] 1993 * TAG-OCTET + LEN [ HASH ] ] 1994 */ 1995 *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED; 1996 *p++ = (unsigned char)( 0x08 + oid_size + hashlen ); 1997 *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED; 1998 *p++ = (unsigned char)( 0x04 + oid_size ); 1999 *p++ = MBEDTLS_ASN1_OID; 2000 *p++ = (unsigned char) oid_size; 2001 memcpy( p, oid, oid_size ); 2002 p += oid_size; 2003 *p++ = MBEDTLS_ASN1_NULL; 2004 *p++ = 0x00; 2005 *p++ = MBEDTLS_ASN1_OCTET_STRING; 2006 *p++ = (unsigned char) hashlen; 2007 memcpy( p, hash, hashlen ); 2008 p += hashlen; 2009 2010 /* Just a sanity-check, should be automatic 2011 * after the initial bounds check. */ 2012 if( p != dst + dst_len ) 2013 { 2014 mbedtls_platform_zeroize( dst, dst_len ); 2015 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2016 } 2017 2018 return( 0 ); 2019 } 2020 2021 /* 2022 * Do an RSA operation to sign the message digest 2023 */ 2024 int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx, 2025 int (*f_rng)(void *, unsigned char *, size_t), 2026 void *p_rng, 2027 int mode, 2028 mbedtls_md_type_t md_alg, 2029 unsigned int hashlen, 2030 const unsigned char *hash, 2031 unsigned char *sig ) 2032 { 2033 int ret; 2034 unsigned char *sig_try = NULL, *verif = NULL; 2035 2036 RSA_VALIDATE_RET( ctx != NULL ); 2037 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2038 mode == MBEDTLS_RSA_PUBLIC ); 2039 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2040 hashlen == 0 ) || 2041 hash != NULL ); 2042 RSA_VALIDATE_RET( sig != NULL ); 2043 2044 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 2045 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2046 2047 /* 2048 * Prepare PKCS1-v1.5 encoding (padding and hash identifier) 2049 */ 2050 2051 if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash, 2052 ctx->len, sig ) ) != 0 ) 2053 return( ret ); 2054 2055 /* 2056 * Call respective RSA primitive 2057 */ 2058 2059 if( mode == MBEDTLS_RSA_PUBLIC ) 2060 { 2061 /* Skip verification on a public key operation */ 2062 return( mbedtls_rsa_public( ctx, sig, sig ) ); 2063 } 2064 2065 /* Private key operation 2066 * 2067 * In order to prevent Lenstra's attack, make the signature in a 2068 * temporary buffer and check it before returning it. 2069 */ 2070 2071 sig_try = mbedtls_calloc( 1, ctx->len ); 2072 if( sig_try == NULL ) 2073 return( MBEDTLS_ERR_MPI_ALLOC_FAILED ); 2074 2075 verif = mbedtls_calloc( 1, ctx->len ); 2076 if( verif == NULL ) 2077 { 2078 mbedtls_free( sig_try ); 2079 return( MBEDTLS_ERR_MPI_ALLOC_FAILED ); 2080 } 2081 2082 MBEDTLS_MPI_CHK( mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig_try ) ); 2083 MBEDTLS_MPI_CHK( mbedtls_rsa_public( ctx, sig_try, verif ) ); 2084 2085 if( mbedtls_safer_memcmp( verif, sig, ctx->len ) != 0 ) 2086 { 2087 ret = MBEDTLS_ERR_RSA_PRIVATE_FAILED; 2088 goto cleanup; 2089 } 2090 2091 memcpy( sig, sig_try, ctx->len ); 2092 2093 cleanup: 2094 mbedtls_free( sig_try ); 2095 mbedtls_free( verif ); 2096 2097 return( ret ); 2098 } 2099 #endif /* MBEDTLS_PKCS1_V15 */ 2100 2101 /* 2102 * Do an RSA operation to sign the message digest 2103 */ 2104 int mbedtls_rsa_pkcs1_sign( mbedtls_rsa_context *ctx, 2105 int (*f_rng)(void *, unsigned char *, size_t), 2106 void *p_rng, 2107 int mode, 2108 mbedtls_md_type_t md_alg, 2109 unsigned int hashlen, 2110 const unsigned char *hash, 2111 unsigned char *sig ) 2112 { 2113 RSA_VALIDATE_RET( ctx != NULL ); 2114 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2115 mode == MBEDTLS_RSA_PUBLIC ); 2116 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2117 hashlen == 0 ) || 2118 hash != NULL ); 2119 RSA_VALIDATE_RET( sig != NULL ); 2120 2121 switch( ctx->padding ) 2122 { 2123 #if defined(MBEDTLS_PKCS1_V15) 2124 case MBEDTLS_RSA_PKCS_V15: 2125 return mbedtls_rsa_rsassa_pkcs1_v15_sign( ctx, f_rng, p_rng, mode, md_alg, 2126 hashlen, hash, sig ); 2127 #endif 2128 2129 #if defined(MBEDTLS_PKCS1_V21) 2130 case MBEDTLS_RSA_PKCS_V21: 2131 return mbedtls_rsa_rsassa_pss_sign( ctx, f_rng, p_rng, mode, md_alg, 2132 hashlen, hash, sig ); 2133 #endif 2134 2135 default: 2136 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 2137 } 2138 } 2139 2140 #if defined(MBEDTLS_PKCS1_V21) 2141 /* 2142 * Implementation of the PKCS#1 v2.1 RSASSA-PSS-VERIFY function 2143 */ 2144 int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx, 2145 int (*f_rng)(void *, unsigned char *, size_t), 2146 void *p_rng, 2147 int mode, 2148 mbedtls_md_type_t md_alg, 2149 unsigned int hashlen, 2150 const unsigned char *hash, 2151 mbedtls_md_type_t mgf1_hash_id, 2152 int expected_salt_len, 2153 const unsigned char *sig ) 2154 { 2155 int ret; 2156 size_t siglen; 2157 unsigned char *p; 2158 unsigned char *hash_start; 2159 unsigned char result[MBEDTLS_MD_MAX_SIZE]; 2160 unsigned char zeros[8]; 2161 unsigned int hlen; 2162 size_t observed_salt_len, msb; 2163 const mbedtls_md_info_t *md_info; 2164 mbedtls_md_context_t md_ctx; 2165 unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; 2166 2167 RSA_VALIDATE_RET( ctx != NULL ); 2168 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2169 mode == MBEDTLS_RSA_PUBLIC ); 2170 RSA_VALIDATE_RET( sig != NULL ); 2171 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2172 hashlen == 0 ) || 2173 hash != NULL ); 2174 2175 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) 2176 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2177 2178 siglen = ctx->len; 2179 2180 if( siglen < 16 || siglen > sizeof( buf ) ) 2181 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2182 2183 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 2184 ? mbedtls_rsa_public( ctx, sig, buf ) 2185 : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, buf ); 2186 2187 if( ret != 0 ) 2188 return( ret ); 2189 2190 p = buf; 2191 2192 if( buf[siglen - 1] != 0xBC ) 2193 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 2194 2195 if( md_alg != MBEDTLS_MD_NONE ) 2196 { 2197 /* Gather length of hash to sign */ 2198 md_info = mbedtls_md_info_from_type( md_alg ); 2199 if( md_info == NULL ) 2200 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2201 2202 hashlen = mbedtls_md_get_size( md_info ); 2203 } 2204 2205 md_info = mbedtls_md_info_from_type( mgf1_hash_id ); 2206 if( md_info == NULL ) 2207 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2208 2209 hlen = mbedtls_md_get_size( md_info ); 2210 2211 memset( zeros, 0, 8 ); 2212 2213 /* 2214 * Note: EMSA-PSS verification is over the length of N - 1 bits 2215 */ 2216 msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; 2217 2218 if( buf[0] >> ( 8 - siglen * 8 + msb ) ) 2219 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2220 2221 /* Compensate for boundary condition when applying mask */ 2222 if( msb % 8 == 0 ) 2223 { 2224 p++; 2225 siglen -= 1; 2226 } 2227 2228 if( siglen < hlen + 2 ) 2229 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2230 hash_start = p + siglen - hlen - 1; 2231 2232 mbedtls_md_init( &md_ctx ); 2233 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 2234 goto exit; 2235 2236 ret = mgf_mask( p, siglen - hlen - 1, hash_start, hlen, &md_ctx ); 2237 if( ret != 0 ) 2238 goto exit; 2239 2240 buf[0] &= 0xFF >> ( siglen * 8 - msb ); 2241 2242 while( p < hash_start - 1 && *p == 0 ) 2243 p++; 2244 2245 if( *p++ != 0x01 ) 2246 { 2247 ret = MBEDTLS_ERR_RSA_INVALID_PADDING; 2248 goto exit; 2249 } 2250 2251 observed_salt_len = hash_start - p; 2252 2253 if( expected_salt_len != MBEDTLS_RSA_SALT_LEN_ANY && 2254 observed_salt_len != (size_t) expected_salt_len ) 2255 { 2256 ret = MBEDTLS_ERR_RSA_INVALID_PADDING; 2257 goto exit; 2258 } 2259 2260 /* 2261 * Generate H = Hash( M' ) 2262 */ 2263 ret = mbedtls_md_starts( &md_ctx ); 2264 if ( ret != 0 ) 2265 goto exit; 2266 ret = mbedtls_md_update( &md_ctx, zeros, 8 ); 2267 if ( ret != 0 ) 2268 goto exit; 2269 ret = mbedtls_md_update( &md_ctx, hash, hashlen ); 2270 if ( ret != 0 ) 2271 goto exit; 2272 ret = mbedtls_md_update( &md_ctx, p, observed_salt_len ); 2273 if ( ret != 0 ) 2274 goto exit; 2275 ret = mbedtls_md_finish( &md_ctx, result ); 2276 if ( ret != 0 ) 2277 goto exit; 2278 2279 if( memcmp( hash_start, result, hlen ) != 0 ) 2280 { 2281 ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; 2282 goto exit; 2283 } 2284 2285 exit: 2286 mbedtls_md_free( &md_ctx ); 2287 2288 return( ret ); 2289 } 2290 2291 /* 2292 * Simplified PKCS#1 v2.1 RSASSA-PSS-VERIFY function 2293 */ 2294 int mbedtls_rsa_rsassa_pss_verify( mbedtls_rsa_context *ctx, 2295 int (*f_rng)(void *, unsigned char *, size_t), 2296 void *p_rng, 2297 int mode, 2298 mbedtls_md_type_t md_alg, 2299 unsigned int hashlen, 2300 const unsigned char *hash, 2301 const unsigned char *sig ) 2302 { 2303 mbedtls_md_type_t mgf1_hash_id; 2304 RSA_VALIDATE_RET( ctx != NULL ); 2305 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2306 mode == MBEDTLS_RSA_PUBLIC ); 2307 RSA_VALIDATE_RET( sig != NULL ); 2308 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2309 hashlen == 0 ) || 2310 hash != NULL ); 2311 2312 mgf1_hash_id = ( ctx->hash_id != MBEDTLS_MD_NONE ) 2313 ? (mbedtls_md_type_t) ctx->hash_id 2314 : md_alg; 2315 2316 return( mbedtls_rsa_rsassa_pss_verify_ext( ctx, f_rng, p_rng, mode, 2317 md_alg, hashlen, hash, 2318 mgf1_hash_id, MBEDTLS_RSA_SALT_LEN_ANY, 2319 sig ) ); 2320 2321 } 2322 #endif /* MBEDTLS_PKCS1_V21 */ 2323 2324 #if defined(MBEDTLS_PKCS1_V15) 2325 /* 2326 * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-v1_5-VERIFY function 2327 */ 2328 int mbedtls_rsa_rsassa_pkcs1_v15_verify( mbedtls_rsa_context *ctx, 2329 int (*f_rng)(void *, unsigned char *, size_t), 2330 void *p_rng, 2331 int mode, 2332 mbedtls_md_type_t md_alg, 2333 unsigned int hashlen, 2334 const unsigned char *hash, 2335 const unsigned char *sig ) 2336 { 2337 int ret = 0; 2338 size_t sig_len; 2339 unsigned char *encoded = NULL, *encoded_expected = NULL; 2340 2341 RSA_VALIDATE_RET( ctx != NULL ); 2342 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2343 mode == MBEDTLS_RSA_PUBLIC ); 2344 RSA_VALIDATE_RET( sig != NULL ); 2345 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2346 hashlen == 0 ) || 2347 hash != NULL ); 2348 2349 sig_len = ctx->len; 2350 2351 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 2352 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2353 2354 /* 2355 * Prepare expected PKCS1 v1.5 encoding of hash. 2356 */ 2357 2358 if( ( encoded = mbedtls_calloc( 1, sig_len ) ) == NULL || 2359 ( encoded_expected = mbedtls_calloc( 1, sig_len ) ) == NULL ) 2360 { 2361 ret = MBEDTLS_ERR_MPI_ALLOC_FAILED; 2362 goto cleanup; 2363 } 2364 2365 if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash, sig_len, 2366 encoded_expected ) ) != 0 ) 2367 goto cleanup; 2368 2369 /* 2370 * Apply RSA primitive to get what should be PKCS1 encoded hash. 2371 */ 2372 2373 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 2374 ? mbedtls_rsa_public( ctx, sig, encoded ) 2375 : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, encoded ); 2376 if( ret != 0 ) 2377 goto cleanup; 2378 2379 /* 2380 * Compare 2381 */ 2382 2383 if( ( ret = mbedtls_safer_memcmp( encoded, encoded_expected, 2384 sig_len ) ) != 0 ) 2385 { 2386 ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; 2387 goto cleanup; 2388 } 2389 2390 cleanup: 2391 2392 if( encoded != NULL ) 2393 { 2394 mbedtls_platform_zeroize( encoded, sig_len ); 2395 mbedtls_free( encoded ); 2396 } 2397 2398 if( encoded_expected != NULL ) 2399 { 2400 mbedtls_platform_zeroize( encoded_expected, sig_len ); 2401 mbedtls_free( encoded_expected ); 2402 } 2403 2404 return( ret ); 2405 } 2406 #endif /* MBEDTLS_PKCS1_V15 */ 2407 2408 /* 2409 * Do an RSA operation and check the message digest 2410 */ 2411 int mbedtls_rsa_pkcs1_verify( mbedtls_rsa_context *ctx, 2412 int (*f_rng)(void *, unsigned char *, size_t), 2413 void *p_rng, 2414 int mode, 2415 mbedtls_md_type_t md_alg, 2416 unsigned int hashlen, 2417 const unsigned char *hash, 2418 const unsigned char *sig ) 2419 { 2420 RSA_VALIDATE_RET( ctx != NULL ); 2421 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2422 mode == MBEDTLS_RSA_PUBLIC ); 2423 RSA_VALIDATE_RET( sig != NULL ); 2424 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2425 hashlen == 0 ) || 2426 hash != NULL ); 2427 2428 switch( ctx->padding ) 2429 { 2430 #if defined(MBEDTLS_PKCS1_V15) 2431 case MBEDTLS_RSA_PKCS_V15: 2432 return mbedtls_rsa_rsassa_pkcs1_v15_verify( ctx, f_rng, p_rng, mode, md_alg, 2433 hashlen, hash, sig ); 2434 #endif 2435 2436 #if defined(MBEDTLS_PKCS1_V21) 2437 case MBEDTLS_RSA_PKCS_V21: 2438 return mbedtls_rsa_rsassa_pss_verify( ctx, f_rng, p_rng, mode, md_alg, 2439 hashlen, hash, sig ); 2440 #endif 2441 2442 default: 2443 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 2444 } 2445 } 2446 2447 /* 2448 * Copy the components of an RSA key 2449 */ 2450 int mbedtls_rsa_copy( mbedtls_rsa_context *dst, const mbedtls_rsa_context *src ) 2451 { 2452 int ret; 2453 RSA_VALIDATE_RET( dst != NULL ); 2454 RSA_VALIDATE_RET( src != NULL ); 2455 2456 dst->ver = src->ver; 2457 dst->len = src->len; 2458 2459 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->N, &src->N ) ); 2460 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->E, &src->E ) ); 2461 2462 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->D, &src->D ) ); 2463 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->P, &src->P ) ); 2464 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Q, &src->Q ) ); 2465 2466 #if !defined(MBEDTLS_RSA_NO_CRT) 2467 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DP, &src->DP ) ); 2468 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DQ, &src->DQ ) ); 2469 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->QP, &src->QP ) ); 2470 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RP, &src->RP ) ); 2471 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RQ, &src->RQ ) ); 2472 #endif 2473 2474 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RN, &src->RN ) ); 2475 2476 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vi, &src->Vi ) ); 2477 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vf, &src->Vf ) ); 2478 2479 dst->padding = src->padding; 2480 dst->hash_id = src->hash_id; 2481 2482 cleanup: 2483 if( ret != 0 ) 2484 mbedtls_rsa_free( dst ); 2485 2486 return( ret ); 2487 } 2488 2489 /* 2490 * Free the components of an RSA key 2491 */ 2492 void mbedtls_rsa_free( mbedtls_rsa_context *ctx ) 2493 { 2494 if( ctx == NULL ) 2495 return; 2496 2497 mbedtls_mpi_free( &ctx->Vi ); 2498 mbedtls_mpi_free( &ctx->Vf ); 2499 mbedtls_mpi_free( &ctx->RN ); 2500 mbedtls_mpi_free( &ctx->D ); 2501 mbedtls_mpi_free( &ctx->Q ); 2502 mbedtls_mpi_free( &ctx->P ); 2503 mbedtls_mpi_free( &ctx->E ); 2504 mbedtls_mpi_free( &ctx->N ); 2505 2506 #if !defined(MBEDTLS_RSA_NO_CRT) 2507 mbedtls_mpi_free( &ctx->RQ ); 2508 mbedtls_mpi_free( &ctx->RP ); 2509 mbedtls_mpi_free( &ctx->QP ); 2510 mbedtls_mpi_free( &ctx->DQ ); 2511 mbedtls_mpi_free( &ctx->DP ); 2512 #endif /* MBEDTLS_RSA_NO_CRT */ 2513 2514 #if defined(MBEDTLS_THREADING_C) 2515 mbedtls_mutex_free( &ctx->mutex ); 2516 #endif 2517 } 2518 2519 #endif /* !MBEDTLS_RSA_ALT */ 2520 2521 #if defined(MBEDTLS_SELF_TEST) 2522 2523 #include "mbedtls/sha1.h" 2524 2525 /* 2526 * Example RSA-1024 keypair, for test purposes 2527 */ 2528 #define KEY_LEN 128 2529 2530 #define RSA_N "9292758453063D803DD603D5E777D788" \ 2531 "8ED1D5BF35786190FA2F23EBC0848AEA" \ 2532 "DDA92CA6C3D80B32C4D109BE0F36D6AE" \ 2533 "7130B9CED7ACDF54CFC7555AC14EEBAB" \ 2534 "93A89813FBF3C4F8066D2D800F7C38A8" \ 2535 "1AE31942917403FF4946B0A83D3D3E05" \ 2536 "EE57C6F5F5606FB5D4BC6CD34EE0801A" \ 2537 "5E94BB77B07507233A0BC7BAC8F90F79" 2538 2539 #define RSA_E "10001" 2540 2541 #define RSA_D "24BF6185468786FDD303083D25E64EFC" \ 2542 "66CA472BC44D253102F8B4A9D3BFA750" \ 2543 "91386C0077937FE33FA3252D28855837" \ 2544 "AE1B484A8A9A45F7EE8C0C634F99E8CD" \ 2545 "DF79C5CE07EE72C7F123142198164234" \ 2546 "CABB724CF78B8173B9F880FC86322407" \ 2547 "AF1FEDFDDE2BEB674CA15F3E81A1521E" \ 2548 "071513A1E85B5DFA031F21ECAE91A34D" 2549 2550 #define RSA_P "C36D0EB7FCD285223CFB5AABA5BDA3D8" \ 2551 "2C01CAD19EA484A87EA4377637E75500" \ 2552 "FCB2005C5C7DD6EC4AC023CDA285D796" \ 2553 "C3D9E75E1EFC42488BB4F1D13AC30A57" 2554 2555 #define RSA_Q "C000DF51A7C77AE8D7C7370C1FF55B69" \ 2556 "E211C2B9E5DB1ED0BF61D0D9899620F4" \ 2557 "910E4168387E3C30AA1E00C339A79508" \ 2558 "8452DD96A9A5EA5D9DCA68DA636032AF" 2559 2560 #define PT_LEN 24 2561 #define RSA_PT "\xAA\xBB\xCC\x03\x02\x01\x00\xFF\xFF\xFF\xFF\xFF" \ 2562 "\x11\x22\x33\x0A\x0B\x0C\xCC\xDD\xDD\xDD\xDD\xDD" 2563 2564 #if defined(MBEDTLS_PKCS1_V15) 2565 static int myrand( void *rng_state, unsigned char *output, size_t len ) 2566 { 2567 #if !defined(__OpenBSD__) 2568 size_t i; 2569 2570 if( rng_state != NULL ) 2571 rng_state = NULL; 2572 2573 for( i = 0; i < len; ++i ) 2574 output[i] = rand(); 2575 #else 2576 if( rng_state != NULL ) 2577 rng_state = NULL; 2578 2579 arc4random_buf( output, len ); 2580 #endif /* !OpenBSD */ 2581 2582 return( 0 ); 2583 } 2584 #endif /* MBEDTLS_PKCS1_V15 */ 2585 2586 /* 2587 * Checkup routine 2588 */ 2589 int mbedtls_rsa_self_test( int verbose ) 2590 { 2591 int ret = 0; 2592 #if defined(MBEDTLS_PKCS1_V15) 2593 size_t len; 2594 mbedtls_rsa_context rsa; 2595 unsigned char rsa_plaintext[PT_LEN]; 2596 unsigned char rsa_decrypted[PT_LEN]; 2597 unsigned char rsa_ciphertext[KEY_LEN]; 2598 #if defined(MBEDTLS_SHA1_C) 2599 unsigned char sha1sum[20]; 2600 #endif 2601 2602 mbedtls_mpi K; 2603 2604 mbedtls_mpi_init( &K ); 2605 mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 ); 2606 2607 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_N ) ); 2608 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, &K, NULL, NULL, NULL, NULL ) ); 2609 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_P ) ); 2610 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, &K, NULL, NULL, NULL ) ); 2611 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_Q ) ); 2612 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, &K, NULL, NULL ) ); 2613 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_D ) ); 2614 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, NULL, &K, NULL ) ); 2615 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_E ) ); 2616 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, NULL, NULL, &K ) ); 2617 2618 MBEDTLS_MPI_CHK( mbedtls_rsa_complete( &rsa ) ); 2619 2620 if( verbose != 0 ) 2621 mbedtls_printf( " RSA key validation: " ); 2622 2623 if( mbedtls_rsa_check_pubkey( &rsa ) != 0 || 2624 mbedtls_rsa_check_privkey( &rsa ) != 0 ) 2625 { 2626 if( verbose != 0 ) 2627 mbedtls_printf( "failed\n" ); 2628 2629 ret = 1; 2630 goto cleanup; 2631 } 2632 2633 if( verbose != 0 ) 2634 mbedtls_printf( "passed\n PKCS#1 encryption : " ); 2635 2636 memcpy( rsa_plaintext, RSA_PT, PT_LEN ); 2637 2638 if( mbedtls_rsa_pkcs1_encrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PUBLIC, 2639 PT_LEN, rsa_plaintext, 2640 rsa_ciphertext ) != 0 ) 2641 { 2642 if( verbose != 0 ) 2643 mbedtls_printf( "failed\n" ); 2644 2645 ret = 1; 2646 goto cleanup; 2647 } 2648 2649 if( verbose != 0 ) 2650 mbedtls_printf( "passed\n PKCS#1 decryption : " ); 2651 2652 if( mbedtls_rsa_pkcs1_decrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PRIVATE, 2653 &len, rsa_ciphertext, rsa_decrypted, 2654 sizeof(rsa_decrypted) ) != 0 ) 2655 { 2656 if( verbose != 0 ) 2657 mbedtls_printf( "failed\n" ); 2658 2659 ret = 1; 2660 goto cleanup; 2661 } 2662 2663 if( memcmp( rsa_decrypted, rsa_plaintext, len ) != 0 ) 2664 { 2665 if( verbose != 0 ) 2666 mbedtls_printf( "failed\n" ); 2667 2668 ret = 1; 2669 goto cleanup; 2670 } 2671 2672 if( verbose != 0 ) 2673 mbedtls_printf( "passed\n" ); 2674 2675 #if defined(MBEDTLS_SHA1_C) 2676 if( verbose != 0 ) 2677 mbedtls_printf( " PKCS#1 data sign : " ); 2678 2679 if( mbedtls_sha1_ret( rsa_plaintext, PT_LEN, sha1sum ) != 0 ) 2680 { 2681 if( verbose != 0 ) 2682 mbedtls_printf( "failed\n" ); 2683 2684 return( 1 ); 2685 } 2686 2687 if( mbedtls_rsa_pkcs1_sign( &rsa, myrand, NULL, 2688 MBEDTLS_RSA_PRIVATE, MBEDTLS_MD_SHA1, 0, 2689 sha1sum, rsa_ciphertext ) != 0 ) 2690 { 2691 if( verbose != 0 ) 2692 mbedtls_printf( "failed\n" ); 2693 2694 ret = 1; 2695 goto cleanup; 2696 } 2697 2698 if( verbose != 0 ) 2699 mbedtls_printf( "passed\n PKCS#1 sig. verify: " ); 2700 2701 if( mbedtls_rsa_pkcs1_verify( &rsa, NULL, NULL, 2702 MBEDTLS_RSA_PUBLIC, MBEDTLS_MD_SHA1, 0, 2703 sha1sum, rsa_ciphertext ) != 0 ) 2704 { 2705 if( verbose != 0 ) 2706 mbedtls_printf( "failed\n" ); 2707 2708 ret = 1; 2709 goto cleanup; 2710 } 2711 2712 if( verbose != 0 ) 2713 mbedtls_printf( "passed\n" ); 2714 #endif /* MBEDTLS_SHA1_C */ 2715 2716 if( verbose != 0 ) 2717 mbedtls_printf( "\n" ); 2718 2719 cleanup: 2720 mbedtls_mpi_free( &K ); 2721 mbedtls_rsa_free( &rsa ); 2722 #else /* MBEDTLS_PKCS1_V15 */ 2723 ((void) verbose); 2724 #endif /* MBEDTLS_PKCS1_V15 */ 2725 return( ret ); 2726 } 2727 2728 #endif /* MBEDTLS_SELF_TEST */ 2729 2730 #endif /* MBEDTLS_RSA_C */ 2731