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 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 1365 ? mbedtls_rsa_public( ctx, input, buf ) 1366 : mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf ); 1367 1368 if( ret != 0 ) 1369 goto cleanup; 1370 1371 /* 1372 * Unmask data and generate lHash 1373 */ 1374 mbedtls_md_init( &md_ctx ); 1375 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 1376 { 1377 mbedtls_md_free( &md_ctx ); 1378 goto cleanup; 1379 } 1380 1381 /* seed: Apply seedMask to maskedSeed */ 1382 if( ( ret = mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1, 1383 &md_ctx ) ) != 0 || 1384 /* DB: Apply dbMask to maskedDB */ 1385 ( ret = mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen, 1386 &md_ctx ) ) != 0 ) 1387 { 1388 mbedtls_md_free( &md_ctx ); 1389 goto cleanup; 1390 } 1391 1392 mbedtls_md_free( &md_ctx ); 1393 1394 /* Generate lHash */ 1395 if( ( ret = mbedtls_md( md_info, label, label_len, lhash ) ) != 0 ) 1396 goto cleanup; 1397 1398 /* 1399 * Check contents, in "constant-time" 1400 */ 1401 p = buf; 1402 bad = 0; 1403 1404 bad |= *p++; /* First byte must be 0 */ 1405 1406 p += hlen; /* Skip seed */ 1407 1408 /* Check lHash */ 1409 for( i = 0; i < hlen; i++ ) 1410 bad |= lhash[i] ^ *p++; 1411 1412 /* Get zero-padding len, but always read till end of buffer 1413 * (minus one, for the 01 byte) */ 1414 pad_len = 0; 1415 pad_done = 0; 1416 for( i = 0; i < ilen - 2 * hlen - 2; i++ ) 1417 { 1418 pad_done |= p[i]; 1419 pad_len += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1; 1420 } 1421 1422 p += pad_len; 1423 bad |= *p++ ^ 0x01; 1424 1425 /* 1426 * The only information "leaked" is whether the padding was correct or not 1427 * (eg, no data is copied if it was not correct). This meets the 1428 * recommendations in PKCS#1 v2.2: an opponent cannot distinguish between 1429 * the different error conditions. 1430 */ 1431 if( bad != 0 ) 1432 { 1433 ret = MBEDTLS_ERR_RSA_INVALID_PADDING; 1434 goto cleanup; 1435 } 1436 1437 if( ilen - ( p - buf ) > output_max_len ) 1438 { 1439 ret = MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE; 1440 goto cleanup; 1441 } 1442 1443 *olen = ilen - (p - buf); 1444 memcpy( output, p, *olen ); 1445 ret = 0; 1446 1447 cleanup: 1448 mbedtls_platform_zeroize( buf, sizeof( buf ) ); 1449 mbedtls_platform_zeroize( lhash, sizeof( lhash ) ); 1450 1451 return( ret ); 1452 } 1453 #endif /* MBEDTLS_PKCS1_V21 */ 1454 1455 #if defined(MBEDTLS_PKCS1_V15) 1456 /** Turn zero-or-nonzero into zero-or-all-bits-one, without branches. 1457 * 1458 * \param value The value to analyze. 1459 * \return Zero if \p value is zero, otherwise all-bits-one. 1460 */ 1461 static unsigned all_or_nothing_int( unsigned value ) 1462 { 1463 /* MSVC has a warning about unary minus on unsigned, but this is 1464 * well-defined and precisely what we want to do here */ 1465 #if defined(_MSC_VER) 1466 #pragma warning( push ) 1467 #pragma warning( disable : 4146 ) 1468 #endif 1469 return( - ( ( value | - value ) >> ( sizeof( value ) * 8 - 1 ) ) ); 1470 #if defined(_MSC_VER) 1471 #pragma warning( pop ) 1472 #endif 1473 } 1474 1475 /** Check whether a size is out of bounds, without branches. 1476 * 1477 * This is equivalent to `size > max`, but is likely to be compiled to 1478 * to code using bitwise operation rather than a branch. 1479 * 1480 * \param size Size to check. 1481 * \param max Maximum desired value for \p size. 1482 * \return \c 0 if `size <= max`. 1483 * \return \c 1 if `size > max`. 1484 */ 1485 static unsigned size_greater_than( size_t size, size_t max ) 1486 { 1487 /* Return the sign bit (1 for negative) of (max - size). */ 1488 return( ( max - size ) >> ( sizeof( size_t ) * 8 - 1 ) ); 1489 } 1490 1491 /** Choose between two integer values, without branches. 1492 * 1493 * This is equivalent to `cond ? if1 : if0`, but is likely to be compiled 1494 * to code using bitwise operation rather than a branch. 1495 * 1496 * \param cond Condition to test. 1497 * \param if1 Value to use if \p cond is nonzero. 1498 * \param if0 Value to use if \p cond is zero. 1499 * \return \c if1 if \p cond is nonzero, otherwise \c if0. 1500 */ 1501 static unsigned if_int( unsigned cond, unsigned if1, unsigned if0 ) 1502 { 1503 unsigned mask = all_or_nothing_int( cond ); 1504 return( ( mask & if1 ) | (~mask & if0 ) ); 1505 } 1506 1507 /** Shift some data towards the left inside a buffer without leaking 1508 * the length of the data through side channels. 1509 * 1510 * `mem_move_to_left(start, total, offset)` is functionally equivalent to 1511 * ``` 1512 * memmove(start, start + offset, total - offset); 1513 * memset(start + offset, 0, total - offset); 1514 * ``` 1515 * but it strives to use a memory access pattern (and thus total timing) 1516 * that does not depend on \p offset. This timing independence comes at 1517 * the expense of performance. 1518 * 1519 * \param start Pointer to the start of the buffer. 1520 * \param total Total size of the buffer. 1521 * \param offset Offset from which to copy \p total - \p offset bytes. 1522 */ 1523 static void mem_move_to_left( void *start, 1524 size_t total, 1525 size_t offset ) 1526 { 1527 volatile unsigned char *buf = start; 1528 size_t i, n; 1529 if( total == 0 ) 1530 return; 1531 for( i = 0; i < total; i++ ) 1532 { 1533 unsigned no_op = size_greater_than( total - offset, i ); 1534 /* The first `total - offset` passes are a no-op. The last 1535 * `offset` passes shift the data one byte to the left and 1536 * zero out the last byte. */ 1537 for( n = 0; n < total - 1; n++ ) 1538 { 1539 unsigned char current = buf[n]; 1540 unsigned char next = buf[n+1]; 1541 buf[n] = if_int( no_op, current, next ); 1542 } 1543 buf[total-1] = if_int( no_op, buf[total-1], 0 ); 1544 } 1545 } 1546 1547 /* 1548 * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-DECRYPT function 1549 */ 1550 int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx, 1551 int (*f_rng)(void *, unsigned char *, size_t), 1552 void *p_rng, 1553 int mode, size_t *olen, 1554 const unsigned char *input, 1555 unsigned char *output, 1556 size_t output_max_len ) 1557 { 1558 int ret; 1559 size_t ilen, i, plaintext_max_size; 1560 unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; 1561 /* The following variables take sensitive values: their value must 1562 * not leak into the observable behavior of the function other than 1563 * the designated outputs (output, olen, return value). Otherwise 1564 * this would open the execution of the function to 1565 * side-channel-based variants of the Bleichenbacher padding oracle 1566 * attack. Potential side channels include overall timing, memory 1567 * access patterns (especially visible to an adversary who has access 1568 * to a shared memory cache), and branches (especially visible to 1569 * an adversary who has access to a shared code cache or to a shared 1570 * branch predictor). */ 1571 size_t pad_count = 0; 1572 unsigned bad = 0; 1573 unsigned char pad_done = 0; 1574 size_t plaintext_size = 0; 1575 unsigned output_too_large; 1576 1577 RSA_VALIDATE_RET( ctx != NULL ); 1578 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1579 mode == MBEDTLS_RSA_PUBLIC ); 1580 RSA_VALIDATE_RET( output_max_len == 0 || output != NULL ); 1581 RSA_VALIDATE_RET( input != NULL ); 1582 RSA_VALIDATE_RET( olen != NULL ); 1583 1584 ilen = ctx->len; 1585 plaintext_max_size = ( output_max_len > ilen - 11 ? 1586 ilen - 11 : 1587 output_max_len ); 1588 1589 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 1590 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1591 1592 if( ilen < 16 || ilen > sizeof( buf ) ) 1593 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1594 1595 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 1596 ? mbedtls_rsa_public( ctx, input, buf ) 1597 : mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf ); 1598 1599 if( ret != 0 ) 1600 goto cleanup; 1601 1602 /* Check and get padding length in constant time and constant 1603 * memory trace. The first byte must be 0. */ 1604 bad |= buf[0]; 1605 1606 if( mode == MBEDTLS_RSA_PRIVATE ) 1607 { 1608 /* Decode EME-PKCS1-v1_5 padding: 0x00 || 0x02 || PS || 0x00 1609 * where PS must be at least 8 nonzero bytes. */ 1610 bad |= buf[1] ^ MBEDTLS_RSA_CRYPT; 1611 1612 /* Read the whole buffer. Set pad_done to nonzero if we find 1613 * the 0x00 byte and remember the padding length in pad_count. */ 1614 for( i = 2; i < ilen; i++ ) 1615 { 1616 pad_done |= ((buf[i] | (unsigned char)-buf[i]) >> 7) ^ 1; 1617 pad_count += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1; 1618 } 1619 } 1620 else 1621 { 1622 /* Decode EMSA-PKCS1-v1_5 padding: 0x00 || 0x01 || PS || 0x00 1623 * where PS must be at least 8 bytes with the value 0xFF. */ 1624 bad |= buf[1] ^ MBEDTLS_RSA_SIGN; 1625 1626 /* Read the whole buffer. Set pad_done to nonzero if we find 1627 * the 0x00 byte and remember the padding length in pad_count. 1628 * If there's a non-0xff byte in the padding, the padding is bad. */ 1629 for( i = 2; i < ilen; i++ ) 1630 { 1631 pad_done |= if_int( buf[i], 0, 1 ); 1632 pad_count += if_int( pad_done, 0, 1 ); 1633 bad |= if_int( pad_done, 0, buf[i] ^ 0xFF ); 1634 } 1635 } 1636 1637 /* If pad_done is still zero, there's no data, only unfinished padding. */ 1638 bad |= if_int( pad_done, 0, 1 ); 1639 1640 /* There must be at least 8 bytes of padding. */ 1641 bad |= size_greater_than( 8, pad_count ); 1642 1643 /* If the padding is valid, set plaintext_size to the number of 1644 * remaining bytes after stripping the padding. If the padding 1645 * is invalid, avoid leaking this fact through the size of the 1646 * output: use the maximum message size that fits in the output 1647 * buffer. Do it without branches to avoid leaking the padding 1648 * validity through timing. RSA keys are small enough that all the 1649 * size_t values involved fit in unsigned int. */ 1650 plaintext_size = if_int( bad, 1651 (unsigned) plaintext_max_size, 1652 (unsigned) ( ilen - pad_count - 3 ) ); 1653 1654 /* Set output_too_large to 0 if the plaintext fits in the output 1655 * buffer and to 1 otherwise. */ 1656 output_too_large = size_greater_than( plaintext_size, 1657 plaintext_max_size ); 1658 1659 /* Set ret without branches to avoid timing attacks. Return: 1660 * - INVALID_PADDING if the padding is bad (bad != 0). 1661 * - OUTPUT_TOO_LARGE if the padding is good but the decrypted 1662 * plaintext does not fit in the output buffer. 1663 * - 0 if the padding is correct. */ 1664 ret = - (int) if_int( bad, - MBEDTLS_ERR_RSA_INVALID_PADDING, 1665 if_int( output_too_large, - MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE, 1666 0 ) ); 1667 1668 /* If the padding is bad or the plaintext is too large, zero the 1669 * data that we're about to copy to the output buffer. 1670 * We need to copy the same amount of data 1671 * from the same buffer whether the padding is good or not to 1672 * avoid leaking the padding validity through overall timing or 1673 * through memory or cache access patterns. */ 1674 bad = all_or_nothing_int( bad | output_too_large ); 1675 for( i = 11; i < ilen; i++ ) 1676 buf[i] &= ~bad; 1677 1678 /* If the plaintext is too large, truncate it to the buffer size. 1679 * Copy anyway to avoid revealing the length through timing, because 1680 * revealing the length is as bad as revealing the padding validity 1681 * for a Bleichenbacher attack. */ 1682 plaintext_size = if_int( output_too_large, 1683 (unsigned) plaintext_max_size, 1684 (unsigned) plaintext_size ); 1685 1686 /* Move the plaintext to the leftmost position where it can start in 1687 * the working buffer, i.e. make it start plaintext_max_size from 1688 * the end of the buffer. Do this with a memory access trace that 1689 * does not depend on the plaintext size. After this move, the 1690 * starting location of the plaintext is no longer sensitive 1691 * information. */ 1692 mem_move_to_left( buf + ilen - plaintext_max_size, 1693 plaintext_max_size, 1694 plaintext_max_size - plaintext_size ); 1695 1696 /* Finally copy the decrypted plaintext plus trailing zeros 1697 * into the output buffer. */ 1698 memcpy( output, buf + ilen - plaintext_max_size, plaintext_max_size ); 1699 1700 /* Report the amount of data we copied to the output buffer. In case 1701 * of errors (bad padding or output too large), the value of *olen 1702 * when this function returns is not specified. Making it equivalent 1703 * to the good case limits the risks of leaking the padding validity. */ 1704 *olen = plaintext_size; 1705 1706 cleanup: 1707 mbedtls_platform_zeroize( buf, sizeof( buf ) ); 1708 1709 return( ret ); 1710 } 1711 #endif /* MBEDTLS_PKCS1_V15 */ 1712 1713 /* 1714 * Do an RSA operation, then remove the message padding 1715 */ 1716 int mbedtls_rsa_pkcs1_decrypt( mbedtls_rsa_context *ctx, 1717 int (*f_rng)(void *, unsigned char *, size_t), 1718 void *p_rng, 1719 int mode, size_t *olen, 1720 const unsigned char *input, 1721 unsigned char *output, 1722 size_t output_max_len) 1723 { 1724 RSA_VALIDATE_RET( ctx != NULL ); 1725 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1726 mode == MBEDTLS_RSA_PUBLIC ); 1727 RSA_VALIDATE_RET( output_max_len == 0 || output != NULL ); 1728 RSA_VALIDATE_RET( input != NULL ); 1729 RSA_VALIDATE_RET( olen != NULL ); 1730 1731 switch( ctx->padding ) 1732 { 1733 #if defined(MBEDTLS_PKCS1_V15) 1734 case MBEDTLS_RSA_PKCS_V15: 1735 return mbedtls_rsa_rsaes_pkcs1_v15_decrypt( ctx, f_rng, p_rng, mode, olen, 1736 input, output, output_max_len ); 1737 #endif 1738 1739 #if defined(MBEDTLS_PKCS1_V21) 1740 case MBEDTLS_RSA_PKCS_V21: 1741 return mbedtls_rsa_rsaes_oaep_decrypt( ctx, f_rng, p_rng, mode, NULL, 0, 1742 olen, input, output, 1743 output_max_len ); 1744 #endif 1745 1746 default: 1747 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 1748 } 1749 } 1750 1751 #if defined(MBEDTLS_PKCS1_V21) 1752 /* 1753 * Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function 1754 */ 1755 int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx, 1756 int (*f_rng)(void *, unsigned char *, size_t), 1757 void *p_rng, 1758 int mode, 1759 mbedtls_md_type_t md_alg, 1760 unsigned int hashlen, 1761 const unsigned char *hash, 1762 unsigned char *sig ) 1763 { 1764 size_t olen; 1765 unsigned char *p = sig; 1766 unsigned char salt[MBEDTLS_MD_MAX_SIZE]; 1767 size_t slen, min_slen, hlen, offset = 0; 1768 int ret; 1769 size_t msb; 1770 const mbedtls_md_info_t *md_info; 1771 mbedtls_md_context_t md_ctx; 1772 RSA_VALIDATE_RET( ctx != NULL ); 1773 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1774 mode == MBEDTLS_RSA_PUBLIC ); 1775 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 1776 hashlen == 0 ) || 1777 hash != NULL ); 1778 RSA_VALIDATE_RET( sig != NULL ); 1779 1780 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) 1781 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1782 1783 if( f_rng == NULL ) 1784 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1785 1786 olen = ctx->len; 1787 1788 if( md_alg != MBEDTLS_MD_NONE ) 1789 { 1790 /* Gather length of hash to sign */ 1791 md_info = mbedtls_md_info_from_type( md_alg ); 1792 if( md_info == NULL ) 1793 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1794 1795 hashlen = mbedtls_md_get_size( md_info ); 1796 } 1797 1798 md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id ); 1799 if( md_info == NULL ) 1800 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1801 1802 hlen = mbedtls_md_get_size( md_info ); 1803 1804 /* Calculate the largest possible salt length. Normally this is the hash 1805 * length, which is the maximum length the salt can have. If there is not 1806 * enough room, use the maximum salt length that fits. The constraint is 1807 * that the hash length plus the salt length plus 2 bytes must be at most 1808 * the key length. This complies with FIPS 186-4 §5.5 (e) and RFC 8017 1809 * (PKCS#1 v2.2) §9.1.1 step 3. */ 1810 min_slen = hlen - 2; 1811 if( olen < hlen + min_slen + 2 ) 1812 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1813 else if( olen >= hlen + hlen + 2 ) 1814 slen = hlen; 1815 else 1816 slen = olen - hlen - 2; 1817 1818 memset( sig, 0, olen ); 1819 1820 /* Generate salt of length slen */ 1821 if( ( ret = f_rng( p_rng, salt, slen ) ) != 0 ) 1822 return( MBEDTLS_ERR_RSA_RNG_FAILED + ret ); 1823 1824 /* Note: EMSA-PSS encoding is over the length of N - 1 bits */ 1825 msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; 1826 p += olen - hlen - slen - 2; 1827 *p++ = 0x01; 1828 memcpy( p, salt, slen ); 1829 p += slen; 1830 1831 mbedtls_md_init( &md_ctx ); 1832 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 1833 goto exit; 1834 1835 /* Generate H = Hash( M' ) */ 1836 if( ( ret = mbedtls_md_starts( &md_ctx ) ) != 0 ) 1837 goto exit; 1838 if( ( ret = mbedtls_md_update( &md_ctx, p, 8 ) ) != 0 ) 1839 goto exit; 1840 if( ( ret = mbedtls_md_update( &md_ctx, hash, hashlen ) ) != 0 ) 1841 goto exit; 1842 if( ( ret = mbedtls_md_update( &md_ctx, salt, slen ) ) != 0 ) 1843 goto exit; 1844 if( ( ret = mbedtls_md_finish( &md_ctx, p ) ) != 0 ) 1845 goto exit; 1846 1847 /* Compensate for boundary condition when applying mask */ 1848 if( msb % 8 == 0 ) 1849 offset = 1; 1850 1851 /* maskedDB: Apply dbMask to DB */ 1852 if( ( ret = mgf_mask( sig + offset, olen - hlen - 1 - offset, p, hlen, 1853 &md_ctx ) ) != 0 ) 1854 goto exit; 1855 1856 msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; 1857 sig[0] &= 0xFF >> ( olen * 8 - msb ); 1858 1859 p += hlen; 1860 *p++ = 0xBC; 1861 1862 mbedtls_platform_zeroize( salt, sizeof( salt ) ); 1863 1864 exit: 1865 mbedtls_md_free( &md_ctx ); 1866 1867 if( ret != 0 ) 1868 return( ret ); 1869 1870 return( ( mode == MBEDTLS_RSA_PUBLIC ) 1871 ? mbedtls_rsa_public( ctx, sig, sig ) 1872 : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig ) ); 1873 } 1874 #endif /* MBEDTLS_PKCS1_V21 */ 1875 1876 #if defined(MBEDTLS_PKCS1_V15) 1877 /* 1878 * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-V1_5-SIGN function 1879 */ 1880 1881 /* Construct a PKCS v1.5 encoding of a hashed message 1882 * 1883 * This is used both for signature generation and verification. 1884 * 1885 * Parameters: 1886 * - md_alg: Identifies the hash algorithm used to generate the given hash; 1887 * MBEDTLS_MD_NONE if raw data is signed. 1888 * - hashlen: Length of hash in case hashlen is MBEDTLS_MD_NONE. 1889 * - hash: Buffer containing the hashed message or the raw data. 1890 * - dst_len: Length of the encoded message. 1891 * - dst: Buffer to hold the encoded message. 1892 * 1893 * Assumptions: 1894 * - hash has size hashlen if md_alg == MBEDTLS_MD_NONE. 1895 * - hash has size corresponding to md_alg if md_alg != MBEDTLS_MD_NONE. 1896 * - dst points to a buffer of size at least dst_len. 1897 * 1898 */ 1899 static int rsa_rsassa_pkcs1_v15_encode( mbedtls_md_type_t md_alg, 1900 unsigned int hashlen, 1901 const unsigned char *hash, 1902 size_t dst_len, 1903 unsigned char *dst ) 1904 { 1905 size_t oid_size = 0; 1906 size_t nb_pad = dst_len; 1907 unsigned char *p = dst; 1908 const char *oid = NULL; 1909 1910 /* Are we signing hashed or raw data? */ 1911 if( md_alg != MBEDTLS_MD_NONE ) 1912 { 1913 const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg ); 1914 if( md_info == NULL ) 1915 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1916 1917 if( mbedtls_oid_get_oid_by_md( md_alg, &oid, &oid_size ) != 0 ) 1918 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1919 1920 hashlen = mbedtls_md_get_size( md_info ); 1921 1922 /* Double-check that 8 + hashlen + oid_size can be used as a 1923 * 1-byte ASN.1 length encoding and that there's no overflow. */ 1924 if( 8 + hashlen + oid_size >= 0x80 || 1925 10 + hashlen < hashlen || 1926 10 + hashlen + oid_size < 10 + hashlen ) 1927 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1928 1929 /* 1930 * Static bounds check: 1931 * - Need 10 bytes for five tag-length pairs. 1932 * (Insist on 1-byte length encodings to protect against variants of 1933 * Bleichenbacher's forgery attack against lax PKCS#1v1.5 verification) 1934 * - Need hashlen bytes for hash 1935 * - Need oid_size bytes for hash alg OID. 1936 */ 1937 if( nb_pad < 10 + hashlen + oid_size ) 1938 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1939 nb_pad -= 10 + hashlen + oid_size; 1940 } 1941 else 1942 { 1943 if( nb_pad < hashlen ) 1944 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1945 1946 nb_pad -= hashlen; 1947 } 1948 1949 /* Need space for signature header and padding delimiter (3 bytes), 1950 * and 8 bytes for the minimal padding */ 1951 if( nb_pad < 3 + 8 ) 1952 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1953 nb_pad -= 3; 1954 1955 /* Now nb_pad is the amount of memory to be filled 1956 * with padding, and at least 8 bytes long. */ 1957 1958 /* Write signature header and padding */ 1959 *p++ = 0; 1960 *p++ = MBEDTLS_RSA_SIGN; 1961 memset( p, 0xFF, nb_pad ); 1962 p += nb_pad; 1963 *p++ = 0; 1964 1965 /* Are we signing raw data? */ 1966 if( md_alg == MBEDTLS_MD_NONE ) 1967 { 1968 memcpy( p, hash, hashlen ); 1969 return( 0 ); 1970 } 1971 1972 /* Signing hashed data, add corresponding ASN.1 structure 1973 * 1974 * DigestInfo ::= SEQUENCE { 1975 * digestAlgorithm DigestAlgorithmIdentifier, 1976 * digest Digest } 1977 * DigestAlgorithmIdentifier ::= AlgorithmIdentifier 1978 * Digest ::= OCTET STRING 1979 * 1980 * Schematic: 1981 * TAG-SEQ + LEN [ TAG-SEQ + LEN [ TAG-OID + LEN [ OID ] 1982 * TAG-NULL + LEN [ NULL ] ] 1983 * TAG-OCTET + LEN [ HASH ] ] 1984 */ 1985 *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED; 1986 *p++ = (unsigned char)( 0x08 + oid_size + hashlen ); 1987 *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED; 1988 *p++ = (unsigned char)( 0x04 + oid_size ); 1989 *p++ = MBEDTLS_ASN1_OID; 1990 *p++ = (unsigned char) oid_size; 1991 memcpy( p, oid, oid_size ); 1992 p += oid_size; 1993 *p++ = MBEDTLS_ASN1_NULL; 1994 *p++ = 0x00; 1995 *p++ = MBEDTLS_ASN1_OCTET_STRING; 1996 *p++ = (unsigned char) hashlen; 1997 memcpy( p, hash, hashlen ); 1998 p += hashlen; 1999 2000 /* Just a sanity-check, should be automatic 2001 * after the initial bounds check. */ 2002 if( p != dst + dst_len ) 2003 { 2004 mbedtls_platform_zeroize( dst, dst_len ); 2005 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2006 } 2007 2008 return( 0 ); 2009 } 2010 2011 /* 2012 * Do an RSA operation to sign the message digest 2013 */ 2014 int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx, 2015 int (*f_rng)(void *, unsigned char *, size_t), 2016 void *p_rng, 2017 int mode, 2018 mbedtls_md_type_t md_alg, 2019 unsigned int hashlen, 2020 const unsigned char *hash, 2021 unsigned char *sig ) 2022 { 2023 int ret; 2024 unsigned char *sig_try = NULL, *verif = NULL; 2025 2026 RSA_VALIDATE_RET( ctx != NULL ); 2027 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2028 mode == MBEDTLS_RSA_PUBLIC ); 2029 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2030 hashlen == 0 ) || 2031 hash != NULL ); 2032 RSA_VALIDATE_RET( sig != NULL ); 2033 2034 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 2035 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2036 2037 /* 2038 * Prepare PKCS1-v1.5 encoding (padding and hash identifier) 2039 */ 2040 2041 if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash, 2042 ctx->len, sig ) ) != 0 ) 2043 return( ret ); 2044 2045 /* 2046 * Call respective RSA primitive 2047 */ 2048 2049 if( mode == MBEDTLS_RSA_PUBLIC ) 2050 { 2051 /* Skip verification on a public key operation */ 2052 return( mbedtls_rsa_public( ctx, sig, sig ) ); 2053 } 2054 2055 /* Private key operation 2056 * 2057 * In order to prevent Lenstra's attack, make the signature in a 2058 * temporary buffer and check it before returning it. 2059 */ 2060 2061 sig_try = mbedtls_calloc( 1, ctx->len ); 2062 if( sig_try == NULL ) 2063 return( MBEDTLS_ERR_MPI_ALLOC_FAILED ); 2064 2065 verif = mbedtls_calloc( 1, ctx->len ); 2066 if( verif == NULL ) 2067 { 2068 mbedtls_free( sig_try ); 2069 return( MBEDTLS_ERR_MPI_ALLOC_FAILED ); 2070 } 2071 2072 MBEDTLS_MPI_CHK( mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig_try ) ); 2073 MBEDTLS_MPI_CHK( mbedtls_rsa_public( ctx, sig_try, verif ) ); 2074 2075 if( mbedtls_safer_memcmp( verif, sig, ctx->len ) != 0 ) 2076 { 2077 ret = MBEDTLS_ERR_RSA_PRIVATE_FAILED; 2078 goto cleanup; 2079 } 2080 2081 memcpy( sig, sig_try, ctx->len ); 2082 2083 cleanup: 2084 mbedtls_free( sig_try ); 2085 mbedtls_free( verif ); 2086 2087 return( ret ); 2088 } 2089 #endif /* MBEDTLS_PKCS1_V15 */ 2090 2091 /* 2092 * Do an RSA operation to sign the message digest 2093 */ 2094 int mbedtls_rsa_pkcs1_sign( mbedtls_rsa_context *ctx, 2095 int (*f_rng)(void *, unsigned char *, size_t), 2096 void *p_rng, 2097 int mode, 2098 mbedtls_md_type_t md_alg, 2099 unsigned int hashlen, 2100 const unsigned char *hash, 2101 unsigned char *sig ) 2102 { 2103 RSA_VALIDATE_RET( ctx != NULL ); 2104 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2105 mode == MBEDTLS_RSA_PUBLIC ); 2106 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2107 hashlen == 0 ) || 2108 hash != NULL ); 2109 RSA_VALIDATE_RET( sig != NULL ); 2110 2111 switch( ctx->padding ) 2112 { 2113 #if defined(MBEDTLS_PKCS1_V15) 2114 case MBEDTLS_RSA_PKCS_V15: 2115 return mbedtls_rsa_rsassa_pkcs1_v15_sign( ctx, f_rng, p_rng, mode, md_alg, 2116 hashlen, hash, sig ); 2117 #endif 2118 2119 #if defined(MBEDTLS_PKCS1_V21) 2120 case MBEDTLS_RSA_PKCS_V21: 2121 return mbedtls_rsa_rsassa_pss_sign( ctx, f_rng, p_rng, mode, md_alg, 2122 hashlen, hash, sig ); 2123 #endif 2124 2125 default: 2126 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 2127 } 2128 } 2129 2130 #if defined(MBEDTLS_PKCS1_V21) 2131 /* 2132 * Implementation of the PKCS#1 v2.1 RSASSA-PSS-VERIFY function 2133 */ 2134 int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx, 2135 int (*f_rng)(void *, unsigned char *, size_t), 2136 void *p_rng, 2137 int mode, 2138 mbedtls_md_type_t md_alg, 2139 unsigned int hashlen, 2140 const unsigned char *hash, 2141 mbedtls_md_type_t mgf1_hash_id, 2142 int expected_salt_len, 2143 const unsigned char *sig ) 2144 { 2145 int ret; 2146 size_t siglen; 2147 unsigned char *p; 2148 unsigned char *hash_start; 2149 unsigned char result[MBEDTLS_MD_MAX_SIZE]; 2150 unsigned char zeros[8]; 2151 unsigned int hlen; 2152 size_t observed_salt_len, msb; 2153 const mbedtls_md_info_t *md_info; 2154 mbedtls_md_context_t md_ctx; 2155 unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; 2156 2157 RSA_VALIDATE_RET( ctx != NULL ); 2158 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2159 mode == MBEDTLS_RSA_PUBLIC ); 2160 RSA_VALIDATE_RET( sig != NULL ); 2161 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2162 hashlen == 0 ) || 2163 hash != NULL ); 2164 2165 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) 2166 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2167 2168 siglen = ctx->len; 2169 2170 if( siglen < 16 || siglen > sizeof( buf ) ) 2171 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2172 2173 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 2174 ? mbedtls_rsa_public( ctx, sig, buf ) 2175 : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, buf ); 2176 2177 if( ret != 0 ) 2178 return( ret ); 2179 2180 p = buf; 2181 2182 if( buf[siglen - 1] != 0xBC ) 2183 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 2184 2185 if( md_alg != MBEDTLS_MD_NONE ) 2186 { 2187 /* Gather length of hash to sign */ 2188 md_info = mbedtls_md_info_from_type( md_alg ); 2189 if( md_info == NULL ) 2190 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2191 2192 hashlen = mbedtls_md_get_size( md_info ); 2193 } 2194 2195 md_info = mbedtls_md_info_from_type( mgf1_hash_id ); 2196 if( md_info == NULL ) 2197 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2198 2199 hlen = mbedtls_md_get_size( md_info ); 2200 2201 memset( zeros, 0, 8 ); 2202 2203 /* 2204 * Note: EMSA-PSS verification is over the length of N - 1 bits 2205 */ 2206 msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; 2207 2208 if( buf[0] >> ( 8 - siglen * 8 + msb ) ) 2209 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2210 2211 /* Compensate for boundary condition when applying mask */ 2212 if( msb % 8 == 0 ) 2213 { 2214 p++; 2215 siglen -= 1; 2216 } 2217 2218 if( siglen < hlen + 2 ) 2219 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2220 hash_start = p + siglen - hlen - 1; 2221 2222 mbedtls_md_init( &md_ctx ); 2223 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 2224 goto exit; 2225 2226 ret = mgf_mask( p, siglen - hlen - 1, hash_start, hlen, &md_ctx ); 2227 if( ret != 0 ) 2228 goto exit; 2229 2230 buf[0] &= 0xFF >> ( siglen * 8 - msb ); 2231 2232 while( p < hash_start - 1 && *p == 0 ) 2233 p++; 2234 2235 if( *p++ != 0x01 ) 2236 { 2237 ret = MBEDTLS_ERR_RSA_INVALID_PADDING; 2238 goto exit; 2239 } 2240 2241 observed_salt_len = hash_start - p; 2242 2243 if( expected_salt_len != MBEDTLS_RSA_SALT_LEN_ANY && 2244 observed_salt_len != (size_t) expected_salt_len ) 2245 { 2246 ret = MBEDTLS_ERR_RSA_INVALID_PADDING; 2247 goto exit; 2248 } 2249 2250 /* 2251 * Generate H = Hash( M' ) 2252 */ 2253 ret = mbedtls_md_starts( &md_ctx ); 2254 if ( ret != 0 ) 2255 goto exit; 2256 ret = mbedtls_md_update( &md_ctx, zeros, 8 ); 2257 if ( ret != 0 ) 2258 goto exit; 2259 ret = mbedtls_md_update( &md_ctx, hash, hashlen ); 2260 if ( ret != 0 ) 2261 goto exit; 2262 ret = mbedtls_md_update( &md_ctx, p, observed_salt_len ); 2263 if ( ret != 0 ) 2264 goto exit; 2265 ret = mbedtls_md_finish( &md_ctx, result ); 2266 if ( ret != 0 ) 2267 goto exit; 2268 2269 if( memcmp( hash_start, result, hlen ) != 0 ) 2270 { 2271 ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; 2272 goto exit; 2273 } 2274 2275 exit: 2276 mbedtls_md_free( &md_ctx ); 2277 2278 return( ret ); 2279 } 2280 2281 /* 2282 * Simplified PKCS#1 v2.1 RSASSA-PSS-VERIFY function 2283 */ 2284 int mbedtls_rsa_rsassa_pss_verify( mbedtls_rsa_context *ctx, 2285 int (*f_rng)(void *, unsigned char *, size_t), 2286 void *p_rng, 2287 int mode, 2288 mbedtls_md_type_t md_alg, 2289 unsigned int hashlen, 2290 const unsigned char *hash, 2291 const unsigned char *sig ) 2292 { 2293 mbedtls_md_type_t mgf1_hash_id; 2294 RSA_VALIDATE_RET( ctx != NULL ); 2295 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2296 mode == MBEDTLS_RSA_PUBLIC ); 2297 RSA_VALIDATE_RET( sig != NULL ); 2298 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2299 hashlen == 0 ) || 2300 hash != NULL ); 2301 2302 mgf1_hash_id = ( ctx->hash_id != MBEDTLS_MD_NONE ) 2303 ? (mbedtls_md_type_t) ctx->hash_id 2304 : md_alg; 2305 2306 return( mbedtls_rsa_rsassa_pss_verify_ext( ctx, f_rng, p_rng, mode, 2307 md_alg, hashlen, hash, 2308 mgf1_hash_id, MBEDTLS_RSA_SALT_LEN_ANY, 2309 sig ) ); 2310 2311 } 2312 #endif /* MBEDTLS_PKCS1_V21 */ 2313 2314 #if defined(MBEDTLS_PKCS1_V15) 2315 /* 2316 * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-v1_5-VERIFY function 2317 */ 2318 int mbedtls_rsa_rsassa_pkcs1_v15_verify( mbedtls_rsa_context *ctx, 2319 int (*f_rng)(void *, unsigned char *, size_t), 2320 void *p_rng, 2321 int mode, 2322 mbedtls_md_type_t md_alg, 2323 unsigned int hashlen, 2324 const unsigned char *hash, 2325 const unsigned char *sig ) 2326 { 2327 int ret = 0; 2328 size_t sig_len; 2329 unsigned char *encoded = NULL, *encoded_expected = NULL; 2330 2331 RSA_VALIDATE_RET( ctx != NULL ); 2332 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2333 mode == MBEDTLS_RSA_PUBLIC ); 2334 RSA_VALIDATE_RET( sig != NULL ); 2335 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2336 hashlen == 0 ) || 2337 hash != NULL ); 2338 2339 sig_len = ctx->len; 2340 2341 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 2342 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2343 2344 /* 2345 * Prepare expected PKCS1 v1.5 encoding of hash. 2346 */ 2347 2348 if( ( encoded = mbedtls_calloc( 1, sig_len ) ) == NULL || 2349 ( encoded_expected = mbedtls_calloc( 1, sig_len ) ) == NULL ) 2350 { 2351 ret = MBEDTLS_ERR_MPI_ALLOC_FAILED; 2352 goto cleanup; 2353 } 2354 2355 if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash, sig_len, 2356 encoded_expected ) ) != 0 ) 2357 goto cleanup; 2358 2359 /* 2360 * Apply RSA primitive to get what should be PKCS1 encoded hash. 2361 */ 2362 2363 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 2364 ? mbedtls_rsa_public( ctx, sig, encoded ) 2365 : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, encoded ); 2366 if( ret != 0 ) 2367 goto cleanup; 2368 2369 /* 2370 * Compare 2371 */ 2372 2373 if( ( ret = mbedtls_safer_memcmp( encoded, encoded_expected, 2374 sig_len ) ) != 0 ) 2375 { 2376 ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; 2377 goto cleanup; 2378 } 2379 2380 cleanup: 2381 2382 if( encoded != NULL ) 2383 { 2384 mbedtls_platform_zeroize( encoded, sig_len ); 2385 mbedtls_free( encoded ); 2386 } 2387 2388 if( encoded_expected != NULL ) 2389 { 2390 mbedtls_platform_zeroize( encoded_expected, sig_len ); 2391 mbedtls_free( encoded_expected ); 2392 } 2393 2394 return( ret ); 2395 } 2396 #endif /* MBEDTLS_PKCS1_V15 */ 2397 2398 /* 2399 * Do an RSA operation and check the message digest 2400 */ 2401 int mbedtls_rsa_pkcs1_verify( mbedtls_rsa_context *ctx, 2402 int (*f_rng)(void *, unsigned char *, size_t), 2403 void *p_rng, 2404 int mode, 2405 mbedtls_md_type_t md_alg, 2406 unsigned int hashlen, 2407 const unsigned char *hash, 2408 const unsigned char *sig ) 2409 { 2410 RSA_VALIDATE_RET( ctx != NULL ); 2411 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2412 mode == MBEDTLS_RSA_PUBLIC ); 2413 RSA_VALIDATE_RET( sig != NULL ); 2414 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2415 hashlen == 0 ) || 2416 hash != NULL ); 2417 2418 switch( ctx->padding ) 2419 { 2420 #if defined(MBEDTLS_PKCS1_V15) 2421 case MBEDTLS_RSA_PKCS_V15: 2422 return mbedtls_rsa_rsassa_pkcs1_v15_verify( ctx, f_rng, p_rng, mode, md_alg, 2423 hashlen, hash, sig ); 2424 #endif 2425 2426 #if defined(MBEDTLS_PKCS1_V21) 2427 case MBEDTLS_RSA_PKCS_V21: 2428 return mbedtls_rsa_rsassa_pss_verify( ctx, f_rng, p_rng, mode, md_alg, 2429 hashlen, hash, sig ); 2430 #endif 2431 2432 default: 2433 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 2434 } 2435 } 2436 2437 /* 2438 * Copy the components of an RSA key 2439 */ 2440 int mbedtls_rsa_copy( mbedtls_rsa_context *dst, const mbedtls_rsa_context *src ) 2441 { 2442 int ret; 2443 RSA_VALIDATE_RET( dst != NULL ); 2444 RSA_VALIDATE_RET( src != NULL ); 2445 2446 dst->ver = src->ver; 2447 dst->len = src->len; 2448 2449 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->N, &src->N ) ); 2450 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->E, &src->E ) ); 2451 2452 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->D, &src->D ) ); 2453 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->P, &src->P ) ); 2454 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Q, &src->Q ) ); 2455 2456 #if !defined(MBEDTLS_RSA_NO_CRT) 2457 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DP, &src->DP ) ); 2458 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DQ, &src->DQ ) ); 2459 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->QP, &src->QP ) ); 2460 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RP, &src->RP ) ); 2461 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RQ, &src->RQ ) ); 2462 #endif 2463 2464 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RN, &src->RN ) ); 2465 2466 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vi, &src->Vi ) ); 2467 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vf, &src->Vf ) ); 2468 2469 dst->padding = src->padding; 2470 dst->hash_id = src->hash_id; 2471 2472 cleanup: 2473 if( ret != 0 ) 2474 mbedtls_rsa_free( dst ); 2475 2476 return( ret ); 2477 } 2478 2479 /* 2480 * Free the components of an RSA key 2481 */ 2482 void mbedtls_rsa_free( mbedtls_rsa_context *ctx ) 2483 { 2484 if( ctx == NULL ) 2485 return; 2486 2487 mbedtls_mpi_free( &ctx->Vi ); 2488 mbedtls_mpi_free( &ctx->Vf ); 2489 mbedtls_mpi_free( &ctx->RN ); 2490 mbedtls_mpi_free( &ctx->D ); 2491 mbedtls_mpi_free( &ctx->Q ); 2492 mbedtls_mpi_free( &ctx->P ); 2493 mbedtls_mpi_free( &ctx->E ); 2494 mbedtls_mpi_free( &ctx->N ); 2495 2496 #if !defined(MBEDTLS_RSA_NO_CRT) 2497 mbedtls_mpi_free( &ctx->RQ ); 2498 mbedtls_mpi_free( &ctx->RP ); 2499 mbedtls_mpi_free( &ctx->QP ); 2500 mbedtls_mpi_free( &ctx->DQ ); 2501 mbedtls_mpi_free( &ctx->DP ); 2502 #endif /* MBEDTLS_RSA_NO_CRT */ 2503 2504 #if defined(MBEDTLS_THREADING_C) 2505 mbedtls_mutex_free( &ctx->mutex ); 2506 #endif 2507 } 2508 2509 #endif /* !MBEDTLS_RSA_ALT */ 2510 2511 #if defined(MBEDTLS_SELF_TEST) 2512 2513 #include "mbedtls/sha1.h" 2514 2515 /* 2516 * Example RSA-1024 keypair, for test purposes 2517 */ 2518 #define KEY_LEN 128 2519 2520 #define RSA_N "9292758453063D803DD603D5E777D788" \ 2521 "8ED1D5BF35786190FA2F23EBC0848AEA" \ 2522 "DDA92CA6C3D80B32C4D109BE0F36D6AE" \ 2523 "7130B9CED7ACDF54CFC7555AC14EEBAB" \ 2524 "93A89813FBF3C4F8066D2D800F7C38A8" \ 2525 "1AE31942917403FF4946B0A83D3D3E05" \ 2526 "EE57C6F5F5606FB5D4BC6CD34EE0801A" \ 2527 "5E94BB77B07507233A0BC7BAC8F90F79" 2528 2529 #define RSA_E "10001" 2530 2531 #define RSA_D "24BF6185468786FDD303083D25E64EFC" \ 2532 "66CA472BC44D253102F8B4A9D3BFA750" \ 2533 "91386C0077937FE33FA3252D28855837" \ 2534 "AE1B484A8A9A45F7EE8C0C634F99E8CD" \ 2535 "DF79C5CE07EE72C7F123142198164234" \ 2536 "CABB724CF78B8173B9F880FC86322407" \ 2537 "AF1FEDFDDE2BEB674CA15F3E81A1521E" \ 2538 "071513A1E85B5DFA031F21ECAE91A34D" 2539 2540 #define RSA_P "C36D0EB7FCD285223CFB5AABA5BDA3D8" \ 2541 "2C01CAD19EA484A87EA4377637E75500" \ 2542 "FCB2005C5C7DD6EC4AC023CDA285D796" \ 2543 "C3D9E75E1EFC42488BB4F1D13AC30A57" 2544 2545 #define RSA_Q "C000DF51A7C77AE8D7C7370C1FF55B69" \ 2546 "E211C2B9E5DB1ED0BF61D0D9899620F4" \ 2547 "910E4168387E3C30AA1E00C339A79508" \ 2548 "8452DD96A9A5EA5D9DCA68DA636032AF" 2549 2550 #define PT_LEN 24 2551 #define RSA_PT "\xAA\xBB\xCC\x03\x02\x01\x00\xFF\xFF\xFF\xFF\xFF" \ 2552 "\x11\x22\x33\x0A\x0B\x0C\xCC\xDD\xDD\xDD\xDD\xDD" 2553 2554 #if defined(MBEDTLS_PKCS1_V15) 2555 static int myrand( void *rng_state, unsigned char *output, size_t len ) 2556 { 2557 #if !defined(__OpenBSD__) 2558 size_t i; 2559 2560 if( rng_state != NULL ) 2561 rng_state = NULL; 2562 2563 for( i = 0; i < len; ++i ) 2564 output[i] = rand(); 2565 #else 2566 if( rng_state != NULL ) 2567 rng_state = NULL; 2568 2569 arc4random_buf( output, len ); 2570 #endif /* !OpenBSD */ 2571 2572 return( 0 ); 2573 } 2574 #endif /* MBEDTLS_PKCS1_V15 */ 2575 2576 /* 2577 * Checkup routine 2578 */ 2579 int mbedtls_rsa_self_test( int verbose ) 2580 { 2581 int ret = 0; 2582 #if defined(MBEDTLS_PKCS1_V15) 2583 size_t len; 2584 mbedtls_rsa_context rsa; 2585 unsigned char rsa_plaintext[PT_LEN]; 2586 unsigned char rsa_decrypted[PT_LEN]; 2587 unsigned char rsa_ciphertext[KEY_LEN]; 2588 #if defined(MBEDTLS_SHA1_C) 2589 unsigned char sha1sum[20]; 2590 #endif 2591 2592 mbedtls_mpi K; 2593 2594 mbedtls_mpi_init( &K ); 2595 mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 ); 2596 2597 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_N ) ); 2598 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, &K, NULL, NULL, NULL, NULL ) ); 2599 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_P ) ); 2600 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, &K, NULL, NULL, NULL ) ); 2601 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_Q ) ); 2602 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, &K, NULL, NULL ) ); 2603 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_D ) ); 2604 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, NULL, &K, NULL ) ); 2605 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_E ) ); 2606 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, NULL, NULL, &K ) ); 2607 2608 MBEDTLS_MPI_CHK( mbedtls_rsa_complete( &rsa ) ); 2609 2610 if( verbose != 0 ) 2611 mbedtls_printf( " RSA key validation: " ); 2612 2613 if( mbedtls_rsa_check_pubkey( &rsa ) != 0 || 2614 mbedtls_rsa_check_privkey( &rsa ) != 0 ) 2615 { 2616 if( verbose != 0 ) 2617 mbedtls_printf( "failed\n" ); 2618 2619 ret = 1; 2620 goto cleanup; 2621 } 2622 2623 if( verbose != 0 ) 2624 mbedtls_printf( "passed\n PKCS#1 encryption : " ); 2625 2626 memcpy( rsa_plaintext, RSA_PT, PT_LEN ); 2627 2628 if( mbedtls_rsa_pkcs1_encrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PUBLIC, 2629 PT_LEN, rsa_plaintext, 2630 rsa_ciphertext ) != 0 ) 2631 { 2632 if( verbose != 0 ) 2633 mbedtls_printf( "failed\n" ); 2634 2635 ret = 1; 2636 goto cleanup; 2637 } 2638 2639 if( verbose != 0 ) 2640 mbedtls_printf( "passed\n PKCS#1 decryption : " ); 2641 2642 if( mbedtls_rsa_pkcs1_decrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PRIVATE, 2643 &len, rsa_ciphertext, rsa_decrypted, 2644 sizeof(rsa_decrypted) ) != 0 ) 2645 { 2646 if( verbose != 0 ) 2647 mbedtls_printf( "failed\n" ); 2648 2649 ret = 1; 2650 goto cleanup; 2651 } 2652 2653 if( memcmp( rsa_decrypted, rsa_plaintext, len ) != 0 ) 2654 { 2655 if( verbose != 0 ) 2656 mbedtls_printf( "failed\n" ); 2657 2658 ret = 1; 2659 goto cleanup; 2660 } 2661 2662 if( verbose != 0 ) 2663 mbedtls_printf( "passed\n" ); 2664 2665 #if defined(MBEDTLS_SHA1_C) 2666 if( verbose != 0 ) 2667 mbedtls_printf( " PKCS#1 data sign : " ); 2668 2669 if( mbedtls_sha1_ret( rsa_plaintext, PT_LEN, sha1sum ) != 0 ) 2670 { 2671 if( verbose != 0 ) 2672 mbedtls_printf( "failed\n" ); 2673 2674 return( 1 ); 2675 } 2676 2677 if( mbedtls_rsa_pkcs1_sign( &rsa, myrand, NULL, 2678 MBEDTLS_RSA_PRIVATE, MBEDTLS_MD_SHA1, 0, 2679 sha1sum, rsa_ciphertext ) != 0 ) 2680 { 2681 if( verbose != 0 ) 2682 mbedtls_printf( "failed\n" ); 2683 2684 ret = 1; 2685 goto cleanup; 2686 } 2687 2688 if( verbose != 0 ) 2689 mbedtls_printf( "passed\n PKCS#1 sig. verify: " ); 2690 2691 if( mbedtls_rsa_pkcs1_verify( &rsa, NULL, NULL, 2692 MBEDTLS_RSA_PUBLIC, MBEDTLS_MD_SHA1, 0, 2693 sha1sum, rsa_ciphertext ) != 0 ) 2694 { 2695 if( verbose != 0 ) 2696 mbedtls_printf( "failed\n" ); 2697 2698 ret = 1; 2699 goto cleanup; 2700 } 2701 2702 if( verbose != 0 ) 2703 mbedtls_printf( "passed\n" ); 2704 #endif /* MBEDTLS_SHA1_C */ 2705 2706 if( verbose != 0 ) 2707 mbedtls_printf( "\n" ); 2708 2709 cleanup: 2710 mbedtls_mpi_free( &K ); 2711 mbedtls_rsa_free( &rsa ); 2712 #else /* MBEDTLS_PKCS1_V15 */ 2713 ((void) verbose); 2714 #endif /* MBEDTLS_PKCS1_V15 */ 2715 return( ret ); 2716 } 2717 2718 #endif /* MBEDTLS_SELF_TEST */ 2719 2720 #endif /* MBEDTLS_RSA_C */ 2721