1 /* 2 * The RSA public-key cryptosystem 3 * 4 * Copyright The Mbed TLS Contributors 5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 6 * 7 * This file is provided under the Apache License 2.0, or the 8 * GNU General Public License v2.0 or later. 9 * 10 * ********** 11 * Apache License 2.0: 12 * 13 * Licensed under the Apache License, Version 2.0 (the "License"); you may 14 * not use this file except in compliance with the License. 15 * You may obtain a copy of the License at 16 * 17 * http://www.apache.org/licenses/LICENSE-2.0 18 * 19 * Unless required by applicable law or agreed to in writing, software 20 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 21 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 22 * See the License for the specific language governing permissions and 23 * limitations under the License. 24 * 25 * ********** 26 * 27 * ********** 28 * GNU General Public License v2.0 or later: 29 * 30 * This program is free software; you can redistribute it and/or modify 31 * it under the terms of the GNU General Public License as published by 32 * the Free Software Foundation; either version 2 of the License, or 33 * (at your option) any later version. 34 * 35 * This program is distributed in the hope that it will be useful, 36 * but WITHOUT ANY WARRANTY; without even the implied warranty of 37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 38 * GNU General Public License for more details. 39 * 40 * You should have received a copy of the GNU General Public License along 41 * with this program; if not, write to the Free Software Foundation, Inc., 42 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 43 * 44 * ********** 45 */ 46 47 /* 48 * The following sources were referenced in the design of this implementation 49 * of the RSA algorithm: 50 * 51 * [1] A method for obtaining digital signatures and public-key cryptosystems 52 * R Rivest, A Shamir, and L Adleman 53 * http://people.csail.mit.edu/rivest/pubs.html#RSA78 54 * 55 * [2] Handbook of Applied Cryptography - 1997, Chapter 8 56 * Menezes, van Oorschot and Vanstone 57 * 58 * [3] Malware Guard Extension: Using SGX to Conceal Cache Attacks 59 * Michael Schwarz, Samuel Weiser, Daniel Gruss, Clémentine Maurice and 60 * Stefan Mangard 61 * https://arxiv.org/abs/1702.08719v2 62 * 63 */ 64 65 #if !defined(MBEDTLS_CONFIG_FILE) 66 #include "mbedtls/config.h" 67 #else 68 #include MBEDTLS_CONFIG_FILE 69 #endif 70 71 #if defined(MBEDTLS_RSA_C) 72 73 #include "mbedtls/rsa.h" 74 #include "mbedtls/rsa_internal.h" 75 #include "mbedtls/oid.h" 76 #include "mbedtls/platform_util.h" 77 78 #include <string.h> 79 80 #if defined(MBEDTLS_PKCS1_V21) 81 #include "mbedtls/md.h" 82 #endif 83 84 #if defined(MBEDTLS_PKCS1_V15) && !defined(__OpenBSD__) && !defined(__NetBSD__) 85 #include <stdlib.h> 86 #endif 87 88 #if defined(MBEDTLS_PLATFORM_C) 89 #include "mbedtls/platform.h" 90 #else 91 #include <stdio.h> 92 #define mbedtls_printf printf 93 #define mbedtls_calloc calloc 94 #define mbedtls_free free 95 #endif 96 97 #if !defined(MBEDTLS_RSA_ALT) 98 99 /* Parameter validation macros */ 100 #define RSA_VALIDATE_RET( cond ) \ 101 MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_RSA_BAD_INPUT_DATA ) 102 #define RSA_VALIDATE( cond ) \ 103 MBEDTLS_INTERNAL_VALIDATE( cond ) 104 105 #if defined(MBEDTLS_PKCS1_V15) 106 /* constant-time buffer comparison */ 107 static inline int mbedtls_safer_memcmp( const void *a, const void *b, size_t n ) 108 { 109 size_t i; 110 const unsigned char *A = (const unsigned char *) a; 111 const unsigned char *B = (const unsigned char *) b; 112 unsigned char diff = 0; 113 114 for( i = 0; i < n; i++ ) 115 diff |= A[i] ^ B[i]; 116 117 return( diff ); 118 } 119 #endif /* MBEDTLS_PKCS1_V15 */ 120 121 int mbedtls_rsa_import( mbedtls_rsa_context *ctx, 122 const mbedtls_mpi *N, 123 const mbedtls_mpi *P, const mbedtls_mpi *Q, 124 const mbedtls_mpi *D, const mbedtls_mpi *E ) 125 { 126 int ret; 127 RSA_VALIDATE_RET( ctx != NULL ); 128 129 if( ( N != NULL && ( ret = mbedtls_mpi_copy( &ctx->N, N ) ) != 0 ) || 130 ( P != NULL && ( ret = mbedtls_mpi_copy( &ctx->P, P ) ) != 0 ) || 131 ( Q != NULL && ( ret = mbedtls_mpi_copy( &ctx->Q, Q ) ) != 0 ) || 132 ( D != NULL && ( ret = mbedtls_mpi_copy( &ctx->D, D ) ) != 0 ) || 133 ( E != NULL && ( ret = mbedtls_mpi_copy( &ctx->E, E ) ) != 0 ) ) 134 { 135 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 136 } 137 138 if( N != NULL ) 139 ctx->len = mbedtls_mpi_size( &ctx->N ); 140 141 return( 0 ); 142 } 143 144 int mbedtls_rsa_import_raw( mbedtls_rsa_context *ctx, 145 unsigned char const *N, size_t N_len, 146 unsigned char const *P, size_t P_len, 147 unsigned char const *Q, size_t Q_len, 148 unsigned char const *D, size_t D_len, 149 unsigned char const *E, size_t E_len ) 150 { 151 int ret = 0; 152 RSA_VALIDATE_RET( ctx != NULL ); 153 154 if( N != NULL ) 155 { 156 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->N, N, N_len ) ); 157 ctx->len = mbedtls_mpi_size( &ctx->N ); 158 } 159 160 if( P != NULL ) 161 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->P, P, P_len ) ); 162 163 if( Q != NULL ) 164 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->Q, Q, Q_len ) ); 165 166 if( D != NULL ) 167 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->D, D, D_len ) ); 168 169 if( E != NULL ) 170 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->E, E, E_len ) ); 171 172 cleanup: 173 174 if( ret != 0 ) 175 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 176 177 return( 0 ); 178 } 179 180 /* 181 * Checks whether the context fields are set in such a way 182 * that the RSA primitives will be able to execute without error. 183 * It does *not* make guarantees for consistency of the parameters. 184 */ 185 static int rsa_check_context( mbedtls_rsa_context const *ctx, int is_priv, 186 int blinding_needed ) 187 { 188 #if !defined(MBEDTLS_RSA_NO_CRT) 189 /* blinding_needed is only used for NO_CRT to decide whether 190 * P,Q need to be present or not. */ 191 ((void) blinding_needed); 192 #endif 193 194 if( ctx->len != mbedtls_mpi_size( &ctx->N ) || 195 ctx->len > MBEDTLS_MPI_MAX_SIZE ) 196 { 197 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 198 } 199 200 /* 201 * 1. Modular exponentiation needs positive, odd moduli. 202 */ 203 204 /* Modular exponentiation wrt. N is always used for 205 * RSA public key operations. */ 206 if( mbedtls_mpi_cmp_int( &ctx->N, 0 ) <= 0 || 207 mbedtls_mpi_get_bit( &ctx->N, 0 ) == 0 ) 208 { 209 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 210 } 211 212 #if !defined(MBEDTLS_RSA_NO_CRT) 213 /* Modular exponentiation for P and Q is only 214 * used for private key operations and if CRT 215 * is used. */ 216 if( is_priv && 217 ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) <= 0 || 218 mbedtls_mpi_get_bit( &ctx->P, 0 ) == 0 || 219 mbedtls_mpi_cmp_int( &ctx->Q, 0 ) <= 0 || 220 mbedtls_mpi_get_bit( &ctx->Q, 0 ) == 0 ) ) 221 { 222 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 223 } 224 #endif /* !MBEDTLS_RSA_NO_CRT */ 225 226 /* 227 * 2. Exponents must be positive 228 */ 229 230 /* Always need E for public key operations */ 231 if( mbedtls_mpi_cmp_int( &ctx->E, 0 ) <= 0 ) 232 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 233 234 #if defined(MBEDTLS_RSA_NO_CRT) 235 /* For private key operations, use D or DP & DQ 236 * as (unblinded) exponents. */ 237 if( is_priv && mbedtls_mpi_cmp_int( &ctx->D, 0 ) <= 0 ) 238 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 239 #else 240 if( is_priv && 241 ( mbedtls_mpi_cmp_int( &ctx->DP, 0 ) <= 0 || 242 mbedtls_mpi_cmp_int( &ctx->DQ, 0 ) <= 0 ) ) 243 { 244 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 245 } 246 #endif /* MBEDTLS_RSA_NO_CRT */ 247 248 /* Blinding shouldn't make exponents negative either, 249 * so check that P, Q >= 1 if that hasn't yet been 250 * done as part of 1. */ 251 #if defined(MBEDTLS_RSA_NO_CRT) 252 if( is_priv && blinding_needed && 253 ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) <= 0 || 254 mbedtls_mpi_cmp_int( &ctx->Q, 0 ) <= 0 ) ) 255 { 256 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 257 } 258 #endif 259 260 /* It wouldn't lead to an error if it wasn't satisfied, 261 * but check for QP >= 1 nonetheless. */ 262 #if !defined(MBEDTLS_RSA_NO_CRT) 263 if( is_priv && 264 mbedtls_mpi_cmp_int( &ctx->QP, 0 ) <= 0 ) 265 { 266 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 267 } 268 #endif 269 270 return( 0 ); 271 } 272 273 int mbedtls_rsa_complete( mbedtls_rsa_context *ctx ) 274 { 275 int ret = 0; 276 int have_N, have_P, have_Q, have_D, have_E; 277 #if !defined(MBEDTLS_RSA_NO_CRT) 278 int have_DP, have_DQ, have_QP; 279 #endif 280 int n_missing, pq_missing, d_missing, is_pub, is_priv; 281 282 RSA_VALIDATE_RET( ctx != NULL ); 283 284 have_N = ( mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 ); 285 have_P = ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 ); 286 have_Q = ( mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 ); 287 have_D = ( mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 ); 288 have_E = ( mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0 ); 289 290 #if !defined(MBEDTLS_RSA_NO_CRT) 291 have_DP = ( mbedtls_mpi_cmp_int( &ctx->DP, 0 ) != 0 ); 292 have_DQ = ( mbedtls_mpi_cmp_int( &ctx->DQ, 0 ) != 0 ); 293 have_QP = ( mbedtls_mpi_cmp_int( &ctx->QP, 0 ) != 0 ); 294 #endif 295 296 /* 297 * Check whether provided parameters are enough 298 * to deduce all others. The following incomplete 299 * parameter sets for private keys are supported: 300 * 301 * (1) P, Q missing. 302 * (2) D and potentially N missing. 303 * 304 */ 305 306 n_missing = have_P && have_Q && have_D && have_E; 307 pq_missing = have_N && !have_P && !have_Q && have_D && have_E; 308 d_missing = have_P && have_Q && !have_D && have_E; 309 is_pub = have_N && !have_P && !have_Q && !have_D && have_E; 310 311 /* These three alternatives are mutually exclusive */ 312 is_priv = n_missing || pq_missing || d_missing; 313 314 if( !is_priv && !is_pub ) 315 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 316 317 /* 318 * Step 1: Deduce N if P, Q are provided. 319 */ 320 321 if( !have_N && have_P && have_Q ) 322 { 323 if( ( ret = mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P, 324 &ctx->Q ) ) != 0 ) 325 { 326 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 327 } 328 329 ctx->len = mbedtls_mpi_size( &ctx->N ); 330 } 331 332 /* 333 * Step 2: Deduce and verify all remaining core parameters. 334 */ 335 336 if( pq_missing ) 337 { 338 ret = mbedtls_rsa_deduce_primes( &ctx->N, &ctx->E, &ctx->D, 339 &ctx->P, &ctx->Q ); 340 if( ret != 0 ) 341 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 342 343 } 344 else if( d_missing ) 345 { 346 if( ( ret = mbedtls_rsa_deduce_private_exponent( &ctx->P, 347 &ctx->Q, 348 &ctx->E, 349 &ctx->D ) ) != 0 ) 350 { 351 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 352 } 353 } 354 355 /* 356 * Step 3: Deduce all additional parameters specific 357 * to our current RSA implementation. 358 */ 359 360 #if !defined(MBEDTLS_RSA_NO_CRT) 361 if( is_priv && ! ( have_DP && have_DQ && have_QP ) ) 362 { 363 ret = mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D, 364 &ctx->DP, &ctx->DQ, &ctx->QP ); 365 if( ret != 0 ) 366 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 367 } 368 #endif /* MBEDTLS_RSA_NO_CRT */ 369 370 /* 371 * Step 3: Basic sanity checks 372 */ 373 374 return( rsa_check_context( ctx, is_priv, 1 ) ); 375 } 376 377 int mbedtls_rsa_export_raw( const mbedtls_rsa_context *ctx, 378 unsigned char *N, size_t N_len, 379 unsigned char *P, size_t P_len, 380 unsigned char *Q, size_t Q_len, 381 unsigned char *D, size_t D_len, 382 unsigned char *E, size_t E_len ) 383 { 384 int ret = 0; 385 int is_priv; 386 RSA_VALIDATE_RET( ctx != NULL ); 387 388 /* Check if key is private or public */ 389 is_priv = 390 mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 && 391 mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 && 392 mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 && 393 mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 && 394 mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0; 395 396 if( !is_priv ) 397 { 398 /* If we're trying to export private parameters for a public key, 399 * something must be wrong. */ 400 if( P != NULL || Q != NULL || D != NULL ) 401 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 402 403 } 404 405 if( N != NULL ) 406 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->N, N, N_len ) ); 407 408 if( P != NULL ) 409 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->P, P, P_len ) ); 410 411 if( Q != NULL ) 412 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->Q, Q, Q_len ) ); 413 414 if( D != NULL ) 415 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->D, D, D_len ) ); 416 417 if( E != NULL ) 418 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->E, E, E_len ) ); 419 420 cleanup: 421 422 return( ret ); 423 } 424 425 int mbedtls_rsa_export( const mbedtls_rsa_context *ctx, 426 mbedtls_mpi *N, mbedtls_mpi *P, mbedtls_mpi *Q, 427 mbedtls_mpi *D, mbedtls_mpi *E ) 428 { 429 int ret; 430 int is_priv; 431 RSA_VALIDATE_RET( ctx != NULL ); 432 433 /* Check if key is private or public */ 434 is_priv = 435 mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 && 436 mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 && 437 mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 && 438 mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 && 439 mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0; 440 441 if( !is_priv ) 442 { 443 /* If we're trying to export private parameters for a public key, 444 * something must be wrong. */ 445 if( P != NULL || Q != NULL || D != NULL ) 446 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 447 448 } 449 450 /* Export all requested core parameters. */ 451 452 if( ( N != NULL && ( ret = mbedtls_mpi_copy( N, &ctx->N ) ) != 0 ) || 453 ( P != NULL && ( ret = mbedtls_mpi_copy( P, &ctx->P ) ) != 0 ) || 454 ( Q != NULL && ( ret = mbedtls_mpi_copy( Q, &ctx->Q ) ) != 0 ) || 455 ( D != NULL && ( ret = mbedtls_mpi_copy( D, &ctx->D ) ) != 0 ) || 456 ( E != NULL && ( ret = mbedtls_mpi_copy( E, &ctx->E ) ) != 0 ) ) 457 { 458 return( ret ); 459 } 460 461 return( 0 ); 462 } 463 464 /* 465 * Export CRT parameters 466 * This must also be implemented if CRT is not used, for being able to 467 * write DER encoded RSA keys. The helper function mbedtls_rsa_deduce_crt 468 * can be used in this case. 469 */ 470 int mbedtls_rsa_export_crt( const mbedtls_rsa_context *ctx, 471 mbedtls_mpi *DP, mbedtls_mpi *DQ, mbedtls_mpi *QP ) 472 { 473 int ret; 474 int is_priv; 475 RSA_VALIDATE_RET( ctx != NULL ); 476 477 /* Check if key is private or public */ 478 is_priv = 479 mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 && 480 mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 && 481 mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 && 482 mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 && 483 mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0; 484 485 if( !is_priv ) 486 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 487 488 #if !defined(MBEDTLS_RSA_NO_CRT) 489 /* Export all requested blinding parameters. */ 490 if( ( DP != NULL && ( ret = mbedtls_mpi_copy( DP, &ctx->DP ) ) != 0 ) || 491 ( DQ != NULL && ( ret = mbedtls_mpi_copy( DQ, &ctx->DQ ) ) != 0 ) || 492 ( QP != NULL && ( ret = mbedtls_mpi_copy( QP, &ctx->QP ) ) != 0 ) ) 493 { 494 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 495 } 496 #else 497 if( ( ret = mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D, 498 DP, DQ, QP ) ) != 0 ) 499 { 500 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret ); 501 } 502 #endif 503 504 return( 0 ); 505 } 506 507 /* 508 * Initialize an RSA context 509 */ 510 void mbedtls_rsa_init( mbedtls_rsa_context *ctx, 511 int padding, 512 int hash_id ) 513 { 514 RSA_VALIDATE( ctx != NULL ); 515 RSA_VALIDATE( padding == MBEDTLS_RSA_PKCS_V15 || 516 padding == MBEDTLS_RSA_PKCS_V21 ); 517 518 memset( ctx, 0, sizeof( mbedtls_rsa_context ) ); 519 520 mbedtls_rsa_set_padding( ctx, padding, hash_id ); 521 522 #if defined(MBEDTLS_THREADING_C) 523 /* Set ctx->ver to nonzero to indicate that the mutex has been 524 * initialized and will need to be freed. */ 525 ctx->ver = 1; 526 mbedtls_mutex_init( &ctx->mutex ); 527 #endif 528 } 529 530 /* 531 * Set padding for an existing RSA context 532 */ 533 void mbedtls_rsa_set_padding( mbedtls_rsa_context *ctx, int padding, 534 int hash_id ) 535 { 536 RSA_VALIDATE( ctx != NULL ); 537 RSA_VALIDATE( padding == MBEDTLS_RSA_PKCS_V15 || 538 padding == MBEDTLS_RSA_PKCS_V21 ); 539 540 ctx->padding = padding; 541 ctx->hash_id = hash_id; 542 } 543 544 /* 545 * Get length in bytes of RSA modulus 546 */ 547 548 size_t mbedtls_rsa_get_len( const mbedtls_rsa_context *ctx ) 549 { 550 return( ctx->len ); 551 } 552 553 554 #if defined(MBEDTLS_GENPRIME) 555 556 /* 557 * Generate an RSA keypair 558 * 559 * This generation method follows the RSA key pair generation procedure of 560 * FIPS 186-4 if 2^16 < exponent < 2^256 and nbits = 2048 or nbits = 3072. 561 */ 562 int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx, 563 int (*f_rng)(void *, unsigned char *, size_t), 564 void *p_rng, 565 unsigned int nbits, int exponent ) 566 { 567 int ret; 568 mbedtls_mpi H, G, L; 569 int prime_quality = 0; 570 RSA_VALIDATE_RET( ctx != NULL ); 571 RSA_VALIDATE_RET( f_rng != NULL ); 572 573 /* 574 * If the modulus is 1024 bit long or shorter, then the security strength of 575 * the RSA algorithm is less than or equal to 80 bits and therefore an error 576 * rate of 2^-80 is sufficient. 577 */ 578 if( nbits > 1024 ) 579 prime_quality = MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR; 580 581 mbedtls_mpi_init( &H ); 582 mbedtls_mpi_init( &G ); 583 mbedtls_mpi_init( &L ); 584 585 if( nbits < 128 || exponent < 3 || nbits % 2 != 0 ) 586 { 587 ret = MBEDTLS_ERR_RSA_BAD_INPUT_DATA; 588 goto cleanup; 589 } 590 591 /* 592 * find primes P and Q with Q < P so that: 593 * 1. |P-Q| > 2^( nbits / 2 - 100 ) 594 * 2. GCD( E, (P-1)*(Q-1) ) == 1 595 * 3. E^-1 mod LCM(P-1, Q-1) > 2^( nbits / 2 ) 596 */ 597 MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &ctx->E, exponent ) ); 598 599 do 600 { 601 MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, nbits >> 1, 602 prime_quality, f_rng, p_rng ) ); 603 604 MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1, 605 prime_quality, f_rng, p_rng ) ); 606 607 /* make sure the difference between p and q is not too small (FIPS 186-4 §B.3.3 step 5.4) */ 608 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &H, &ctx->P, &ctx->Q ) ); 609 if( mbedtls_mpi_bitlen( &H ) <= ( ( nbits >= 200 ) ? ( ( nbits >> 1 ) - 99 ) : 0 ) ) 610 continue; 611 612 /* not required by any standards, but some users rely on the fact that P > Q */ 613 if( H.s < 0 ) 614 mbedtls_mpi_swap( &ctx->P, &ctx->Q ); 615 616 /* Temporarily replace P,Q by P-1, Q-1 */ 617 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &ctx->P, &ctx->P, 1 ) ); 618 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &ctx->Q, &ctx->Q, 1 ) ); 619 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &ctx->P, &ctx->Q ) ); 620 621 /* check GCD( E, (P-1)*(Q-1) ) == 1 (FIPS 186-4 §B.3.1 criterion 2(a)) */ 622 MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->E, &H ) ); 623 if( mbedtls_mpi_cmp_int( &G, 1 ) != 0 ) 624 continue; 625 626 /* compute smallest possible D = E^-1 mod LCM(P-1, Q-1) (FIPS 186-4 §B.3.1 criterion 3(b)) */ 627 MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->P, &ctx->Q ) ); 628 MBEDTLS_MPI_CHK( mbedtls_mpi_div_mpi( &L, NULL, &H, &G ) ); 629 MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->D, &ctx->E, &L ) ); 630 631 if( mbedtls_mpi_bitlen( &ctx->D ) <= ( ( nbits + 1 ) / 2 ) ) // (FIPS 186-4 §B.3.1 criterion 3(a)) 632 continue; 633 634 break; 635 } 636 while( 1 ); 637 638 /* Restore P,Q */ 639 MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( &ctx->P, &ctx->P, 1 ) ); 640 MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( &ctx->Q, &ctx->Q, 1 ) ); 641 642 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) ); 643 644 ctx->len = mbedtls_mpi_size( &ctx->N ); 645 646 #if !defined(MBEDTLS_RSA_NO_CRT) 647 /* 648 * DP = D mod (P - 1) 649 * DQ = D mod (Q - 1) 650 * QP = Q^-1 mod P 651 */ 652 MBEDTLS_MPI_CHK( mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D, 653 &ctx->DP, &ctx->DQ, &ctx->QP ) ); 654 #endif /* MBEDTLS_RSA_NO_CRT */ 655 656 /* Double-check */ 657 MBEDTLS_MPI_CHK( mbedtls_rsa_check_privkey( ctx ) ); 658 659 cleanup: 660 661 mbedtls_mpi_free( &H ); 662 mbedtls_mpi_free( &G ); 663 mbedtls_mpi_free( &L ); 664 665 if( ret != 0 ) 666 { 667 mbedtls_rsa_free( ctx ); 668 if( ( -ret & ~0x7f ) == 0 ) 669 ret = MBEDTLS_ERR_RSA_KEY_GEN_FAILED + ret; 670 return( ret ); 671 } 672 673 return( 0 ); 674 } 675 676 #endif /* MBEDTLS_GENPRIME */ 677 678 /* 679 * Check a public RSA key 680 */ 681 int mbedtls_rsa_check_pubkey( const mbedtls_rsa_context *ctx ) 682 { 683 RSA_VALIDATE_RET( ctx != NULL ); 684 685 if( rsa_check_context( ctx, 0 /* public */, 0 /* no blinding */ ) != 0 ) 686 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 687 688 if( mbedtls_mpi_bitlen( &ctx->N ) < 128 ) 689 { 690 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 691 } 692 693 if( mbedtls_mpi_get_bit( &ctx->E, 0 ) == 0 || 694 mbedtls_mpi_bitlen( &ctx->E ) < 2 || 695 mbedtls_mpi_cmp_mpi( &ctx->E, &ctx->N ) >= 0 ) 696 { 697 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 698 } 699 700 return( 0 ); 701 } 702 703 /* 704 * Check for the consistency of all fields in an RSA private key context 705 */ 706 int mbedtls_rsa_check_privkey( const mbedtls_rsa_context *ctx ) 707 { 708 RSA_VALIDATE_RET( ctx != NULL ); 709 710 if( mbedtls_rsa_check_pubkey( ctx ) != 0 || 711 rsa_check_context( ctx, 1 /* private */, 1 /* blinding */ ) != 0 ) 712 { 713 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 714 } 715 716 if( mbedtls_rsa_validate_params( &ctx->N, &ctx->P, &ctx->Q, 717 &ctx->D, &ctx->E, NULL, NULL ) != 0 ) 718 { 719 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 720 } 721 722 #if !defined(MBEDTLS_RSA_NO_CRT) 723 else if( mbedtls_rsa_validate_crt( &ctx->P, &ctx->Q, &ctx->D, 724 &ctx->DP, &ctx->DQ, &ctx->QP ) != 0 ) 725 { 726 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 727 } 728 #endif 729 730 return( 0 ); 731 } 732 733 /* 734 * Check if contexts holding a public and private key match 735 */ 736 int mbedtls_rsa_check_pub_priv( const mbedtls_rsa_context *pub, 737 const mbedtls_rsa_context *prv ) 738 { 739 RSA_VALIDATE_RET( pub != NULL ); 740 RSA_VALIDATE_RET( prv != NULL ); 741 742 if( mbedtls_rsa_check_pubkey( pub ) != 0 || 743 mbedtls_rsa_check_privkey( prv ) != 0 ) 744 { 745 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 746 } 747 748 if( mbedtls_mpi_cmp_mpi( &pub->N, &prv->N ) != 0 || 749 mbedtls_mpi_cmp_mpi( &pub->E, &prv->E ) != 0 ) 750 { 751 return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED ); 752 } 753 754 return( 0 ); 755 } 756 757 /* 758 * Do an RSA public key operation 759 */ 760 int mbedtls_rsa_public( mbedtls_rsa_context *ctx, 761 const unsigned char *input, 762 unsigned char *output ) 763 { 764 int ret; 765 size_t olen; 766 mbedtls_mpi T; 767 RSA_VALIDATE_RET( ctx != NULL ); 768 RSA_VALIDATE_RET( input != NULL ); 769 RSA_VALIDATE_RET( output != NULL ); 770 771 if( rsa_check_context( ctx, 0 /* public */, 0 /* no blinding */ ) ) 772 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 773 774 mbedtls_mpi_init( &T ); 775 776 #if defined(MBEDTLS_THREADING_C) 777 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) 778 return( ret ); 779 #endif 780 781 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) ); 782 783 if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 ) 784 { 785 ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA; 786 goto cleanup; 787 } 788 789 olen = ctx->len; 790 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, &ctx->E, &ctx->N, &ctx->RN ) ); 791 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) ); 792 793 cleanup: 794 #if defined(MBEDTLS_THREADING_C) 795 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) 796 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); 797 #endif 798 799 mbedtls_mpi_free( &T ); 800 801 if( ret != 0 ) 802 return( MBEDTLS_ERR_RSA_PUBLIC_FAILED + ret ); 803 804 return( 0 ); 805 } 806 807 /* 808 * Generate or update blinding values, see section 10 of: 809 * KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA, 810 * DSS, and other systems. In : Advances in Cryptology-CRYPTO'96. Springer 811 * Berlin Heidelberg, 1996. p. 104-113. 812 */ 813 static int rsa_prepare_blinding( mbedtls_rsa_context *ctx, 814 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) 815 { 816 int ret, count = 0; 817 mbedtls_mpi R; 818 819 mbedtls_mpi_init( &R ); 820 821 if( ctx->Vf.p != NULL ) 822 { 823 /* We already have blinding values, just update them by squaring */ 824 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &ctx->Vi ) ); 825 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) ); 826 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, &ctx->Vf ) ); 827 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->N ) ); 828 829 goto cleanup; 830 } 831 832 /* Unblinding value: Vf = random number, invertible mod N */ 833 do { 834 if( count++ > 10 ) 835 { 836 ret = MBEDTLS_ERR_RSA_RNG_FAILED; 837 goto cleanup; 838 } 839 840 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->Vf, ctx->len - 1, f_rng, p_rng ) ); 841 842 /* Compute Vf^-1 as R * (R Vf)^-1 to avoid leaks from inv_mod. */ 843 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, ctx->len - 1, f_rng, p_rng ) ); 844 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vf, &R ) ); 845 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) ); 846 847 /* At this point, Vi is invertible mod N if and only if both Vf and R 848 * are invertible mod N. If one of them isn't, we don't need to know 849 * which one, we just loop and choose new values for both of them. 850 * (Each iteration succeeds with overwhelming probability.) */ 851 ret = mbedtls_mpi_inv_mod( &ctx->Vi, &ctx->Vi, &ctx->N ); 852 if( ret != 0 && ret != MBEDTLS_ERR_MPI_NOT_ACCEPTABLE ) 853 goto cleanup; 854 855 } while( ret == MBEDTLS_ERR_MPI_NOT_ACCEPTABLE ); 856 857 /* Finish the computation of Vf^-1 = R * (R Vf)^-1 */ 858 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &R ) ); 859 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) ); 860 861 /* Blinding value: Vi = Vf^(-e) mod N 862 * (Vi already contains Vf^-1 at this point) */ 863 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->Vi, &ctx->Vi, &ctx->E, &ctx->N, &ctx->RN ) ); 864 865 866 cleanup: 867 mbedtls_mpi_free( &R ); 868 869 return( ret ); 870 } 871 872 /* 873 * Exponent blinding supposed to prevent side-channel attacks using multiple 874 * traces of measurements to recover the RSA key. The more collisions are there, 875 * the more bits of the key can be recovered. See [3]. 876 * 877 * Collecting n collisions with m bit long blinding value requires 2^(m-m/n) 878 * observations on avarage. 879 * 880 * For example with 28 byte blinding to achieve 2 collisions the adversary has 881 * to make 2^112 observations on avarage. 882 * 883 * (With the currently (as of 2017 April) known best algorithms breaking 2048 884 * bit RSA requires approximately as much time as trying out 2^112 random keys. 885 * Thus in this sense with 28 byte blinding the security is not reduced by 886 * side-channel attacks like the one in [3]) 887 * 888 * This countermeasure does not help if the key recovery is possible with a 889 * single trace. 890 */ 891 #define RSA_EXPONENT_BLINDING 28 892 893 /* 894 * Do an RSA private key operation 895 */ 896 int mbedtls_rsa_private( mbedtls_rsa_context *ctx, 897 int (*f_rng)(void *, unsigned char *, size_t), 898 void *p_rng, 899 const unsigned char *input, 900 unsigned char *output ) 901 { 902 int ret; 903 size_t olen; 904 905 /* Temporary holding the result */ 906 mbedtls_mpi T; 907 908 /* Temporaries holding P-1, Q-1 and the 909 * exponent blinding factor, respectively. */ 910 mbedtls_mpi P1, Q1, R; 911 912 #if !defined(MBEDTLS_RSA_NO_CRT) 913 /* Temporaries holding the results mod p resp. mod q. */ 914 mbedtls_mpi TP, TQ; 915 916 /* Temporaries holding the blinded exponents for 917 * the mod p resp. mod q computation (if used). */ 918 mbedtls_mpi DP_blind, DQ_blind; 919 920 /* Pointers to actual exponents to be used - either the unblinded 921 * or the blinded ones, depending on the presence of a PRNG. */ 922 mbedtls_mpi *DP = &ctx->DP; 923 mbedtls_mpi *DQ = &ctx->DQ; 924 #else 925 /* Temporary holding the blinded exponent (if used). */ 926 mbedtls_mpi D_blind; 927 928 /* Pointer to actual exponent to be used - either the unblinded 929 * or the blinded one, depending on the presence of a PRNG. */ 930 mbedtls_mpi *D = &ctx->D; 931 #endif /* MBEDTLS_RSA_NO_CRT */ 932 933 /* Temporaries holding the initial input and the double 934 * checked result; should be the same in the end. */ 935 mbedtls_mpi I, C; 936 937 RSA_VALIDATE_RET( ctx != NULL ); 938 RSA_VALIDATE_RET( input != NULL ); 939 RSA_VALIDATE_RET( output != NULL ); 940 941 if( rsa_check_context( ctx, 1 /* private key checks */, 942 f_rng != NULL /* blinding y/n */ ) != 0 ) 943 { 944 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 945 } 946 947 #if defined(MBEDTLS_THREADING_C) 948 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) 949 return( ret ); 950 #endif 951 952 /* MPI Initialization */ 953 mbedtls_mpi_init( &T ); 954 955 mbedtls_mpi_init( &P1 ); 956 mbedtls_mpi_init( &Q1 ); 957 mbedtls_mpi_init( &R ); 958 959 if( f_rng != NULL ) 960 { 961 #if defined(MBEDTLS_RSA_NO_CRT) 962 mbedtls_mpi_init( &D_blind ); 963 #else 964 mbedtls_mpi_init( &DP_blind ); 965 mbedtls_mpi_init( &DQ_blind ); 966 #endif 967 } 968 969 #if !defined(MBEDTLS_RSA_NO_CRT) 970 mbedtls_mpi_init( &TP ); mbedtls_mpi_init( &TQ ); 971 #endif 972 973 mbedtls_mpi_init( &I ); 974 mbedtls_mpi_init( &C ); 975 976 /* End of MPI initialization */ 977 978 MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) ); 979 if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 ) 980 { 981 ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA; 982 goto cleanup; 983 } 984 985 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &I, &T ) ); 986 987 if( f_rng != NULL ) 988 { 989 /* 990 * Blinding 991 * T = T * Vi mod N 992 */ 993 MBEDTLS_MPI_CHK( rsa_prepare_blinding( ctx, f_rng, p_rng ) ); 994 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vi ) ); 995 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) ); 996 997 /* 998 * Exponent blinding 999 */ 1000 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) ); 1001 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) ); 1002 1003 #if defined(MBEDTLS_RSA_NO_CRT) 1004 /* 1005 * D_blind = ( P - 1 ) * ( Q - 1 ) * R + D 1006 */ 1007 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING, 1008 f_rng, p_rng ) ); 1009 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &D_blind, &P1, &Q1 ) ); 1010 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &D_blind, &D_blind, &R ) ); 1011 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &D_blind, &D_blind, &ctx->D ) ); 1012 1013 D = &D_blind; 1014 #else 1015 /* 1016 * DP_blind = ( P - 1 ) * R + DP 1017 */ 1018 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING, 1019 f_rng, p_rng ) ); 1020 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DP_blind, &P1, &R ) ); 1021 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &DP_blind, &DP_blind, 1022 &ctx->DP ) ); 1023 1024 DP = &DP_blind; 1025 1026 /* 1027 * DQ_blind = ( Q - 1 ) * R + DQ 1028 */ 1029 MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING, 1030 f_rng, p_rng ) ); 1031 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DQ_blind, &Q1, &R ) ); 1032 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &DQ_blind, &DQ_blind, 1033 &ctx->DQ ) ); 1034 1035 DQ = &DQ_blind; 1036 #endif /* MBEDTLS_RSA_NO_CRT */ 1037 } 1038 1039 #if defined(MBEDTLS_RSA_NO_CRT) 1040 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, D, &ctx->N, &ctx->RN ) ); 1041 #else 1042 /* 1043 * Faster decryption using the CRT 1044 * 1045 * TP = input ^ dP mod P 1046 * TQ = input ^ dQ mod Q 1047 */ 1048 1049 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &TP, &T, DP, &ctx->P, &ctx->RP ) ); 1050 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &TQ, &T, DQ, &ctx->Q, &ctx->RQ ) ); 1051 1052 /* 1053 * T = (TP - TQ) * (Q^-1 mod P) mod P 1054 */ 1055 MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &T, &TP, &TQ ) ); 1056 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &TP, &T, &ctx->QP ) ); 1057 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &TP, &ctx->P ) ); 1058 1059 /* 1060 * T = TQ + T * Q 1061 */ 1062 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &TP, &T, &ctx->Q ) ); 1063 MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &TQ, &TP ) ); 1064 #endif /* MBEDTLS_RSA_NO_CRT */ 1065 1066 if( f_rng != NULL ) 1067 { 1068 /* 1069 * Unblind 1070 * T = T * Vf mod N 1071 */ 1072 MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vf ) ); 1073 MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) ); 1074 } 1075 1076 /* Verify the result to prevent glitching attacks. */ 1077 MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &C, &T, &ctx->E, 1078 &ctx->N, &ctx->RN ) ); 1079 if( mbedtls_mpi_cmp_mpi( &C, &I ) != 0 ) 1080 { 1081 ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; 1082 goto cleanup; 1083 } 1084 1085 olen = ctx->len; 1086 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) ); 1087 1088 cleanup: 1089 #if defined(MBEDTLS_THREADING_C) 1090 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) 1091 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); 1092 #endif 1093 1094 mbedtls_mpi_free( &P1 ); 1095 mbedtls_mpi_free( &Q1 ); 1096 mbedtls_mpi_free( &R ); 1097 1098 if( f_rng != NULL ) 1099 { 1100 #if defined(MBEDTLS_RSA_NO_CRT) 1101 mbedtls_mpi_free( &D_blind ); 1102 #else 1103 mbedtls_mpi_free( &DP_blind ); 1104 mbedtls_mpi_free( &DQ_blind ); 1105 #endif 1106 } 1107 1108 mbedtls_mpi_free( &T ); 1109 1110 #if !defined(MBEDTLS_RSA_NO_CRT) 1111 mbedtls_mpi_free( &TP ); mbedtls_mpi_free( &TQ ); 1112 #endif 1113 1114 mbedtls_mpi_free( &C ); 1115 mbedtls_mpi_free( &I ); 1116 1117 if( ret != 0 && ret >= -0x007f ) 1118 return( MBEDTLS_ERR_RSA_PRIVATE_FAILED + ret ); 1119 1120 return( ret ); 1121 } 1122 1123 #if defined(MBEDTLS_PKCS1_V21) 1124 /** 1125 * Generate and apply the MGF1 operation (from PKCS#1 v2.1) to a buffer. 1126 * 1127 * \param dst buffer to mask 1128 * \param dlen length of destination buffer 1129 * \param src source of the mask generation 1130 * \param slen length of the source buffer 1131 * \param md_ctx message digest context to use 1132 */ 1133 static int mgf_mask( unsigned char *dst, size_t dlen, unsigned char *src, 1134 size_t slen, mbedtls_md_context_t *md_ctx ) 1135 { 1136 unsigned char mask[MBEDTLS_MD_MAX_SIZE]; 1137 unsigned char counter[4]; 1138 unsigned char *p; 1139 unsigned int hlen; 1140 size_t i, use_len; 1141 int ret = 0; 1142 1143 memset( mask, 0, MBEDTLS_MD_MAX_SIZE ); 1144 memset( counter, 0, 4 ); 1145 1146 hlen = mbedtls_md_get_size( md_ctx->md_info ); 1147 1148 /* Generate and apply dbMask */ 1149 p = dst; 1150 1151 while( dlen > 0 ) 1152 { 1153 use_len = hlen; 1154 if( dlen < hlen ) 1155 use_len = dlen; 1156 1157 if( ( ret = mbedtls_md_starts( md_ctx ) ) != 0 ) 1158 goto exit; 1159 if( ( ret = mbedtls_md_update( md_ctx, src, slen ) ) != 0 ) 1160 goto exit; 1161 if( ( ret = mbedtls_md_update( md_ctx, counter, 4 ) ) != 0 ) 1162 goto exit; 1163 if( ( ret = mbedtls_md_finish( md_ctx, mask ) ) != 0 ) 1164 goto exit; 1165 1166 for( i = 0; i < use_len; ++i ) 1167 *p++ ^= mask[i]; 1168 1169 counter[3]++; 1170 1171 dlen -= use_len; 1172 } 1173 1174 exit: 1175 mbedtls_platform_zeroize( mask, sizeof( mask ) ); 1176 1177 return( ret ); 1178 } 1179 #endif /* MBEDTLS_PKCS1_V21 */ 1180 1181 #if defined(MBEDTLS_PKCS1_V21) 1182 /* 1183 * Implementation of the PKCS#1 v2.1 RSAES-OAEP-ENCRYPT function 1184 */ 1185 int mbedtls_rsa_rsaes_oaep_encrypt( mbedtls_rsa_context *ctx, 1186 int (*f_rng)(void *, unsigned char *, size_t), 1187 void *p_rng, 1188 int mode, 1189 const unsigned char *label, size_t label_len, 1190 size_t ilen, 1191 const unsigned char *input, 1192 unsigned char *output ) 1193 { 1194 size_t olen; 1195 int ret; 1196 unsigned char *p = output; 1197 unsigned int hlen; 1198 const mbedtls_md_info_t *md_info; 1199 mbedtls_md_context_t md_ctx; 1200 1201 RSA_VALIDATE_RET( ctx != NULL ); 1202 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1203 mode == MBEDTLS_RSA_PUBLIC ); 1204 RSA_VALIDATE_RET( output != NULL ); 1205 RSA_VALIDATE_RET( input != NULL ); 1206 RSA_VALIDATE_RET( label_len == 0 || label != NULL ); 1207 1208 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) 1209 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1210 1211 if( f_rng == NULL ) 1212 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1213 1214 md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id ); 1215 if( md_info == NULL ) 1216 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1217 1218 olen = ctx->len; 1219 hlen = mbedtls_md_get_size( md_info ); 1220 1221 /* first comparison checks for overflow */ 1222 if( ilen + 2 * hlen + 2 < ilen || olen < ilen + 2 * hlen + 2 ) 1223 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1224 1225 memset( output, 0, olen ); 1226 1227 *p++ = 0; 1228 1229 /* Generate a random octet string seed */ 1230 if( ( ret = f_rng( p_rng, p, hlen ) ) != 0 ) 1231 return( MBEDTLS_ERR_RSA_RNG_FAILED + ret ); 1232 1233 p += hlen; 1234 1235 /* Construct DB */ 1236 if( ( ret = mbedtls_md( md_info, label, label_len, p ) ) != 0 ) 1237 return( ret ); 1238 p += hlen; 1239 p += olen - 2 * hlen - 2 - ilen; 1240 *p++ = 1; 1241 memcpy( p, input, ilen ); 1242 1243 mbedtls_md_init( &md_ctx ); 1244 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 1245 goto exit; 1246 1247 /* maskedDB: Apply dbMask to DB */ 1248 if( ( ret = mgf_mask( output + hlen + 1, olen - hlen - 1, output + 1, hlen, 1249 &md_ctx ) ) != 0 ) 1250 goto exit; 1251 1252 /* maskedSeed: Apply seedMask to seed */ 1253 if( ( ret = mgf_mask( output + 1, hlen, output + hlen + 1, olen - hlen - 1, 1254 &md_ctx ) ) != 0 ) 1255 goto exit; 1256 1257 exit: 1258 mbedtls_md_free( &md_ctx ); 1259 1260 if( ret != 0 ) 1261 return( ret ); 1262 1263 return( ( mode == MBEDTLS_RSA_PUBLIC ) 1264 ? mbedtls_rsa_public( ctx, output, output ) 1265 : mbedtls_rsa_private( ctx, f_rng, p_rng, output, output ) ); 1266 } 1267 #endif /* MBEDTLS_PKCS1_V21 */ 1268 1269 #if defined(MBEDTLS_PKCS1_V15) 1270 /* 1271 * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-ENCRYPT function 1272 */ 1273 int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx, 1274 int (*f_rng)(void *, unsigned char *, size_t), 1275 void *p_rng, 1276 int mode, size_t ilen, 1277 const unsigned char *input, 1278 unsigned char *output ) 1279 { 1280 size_t nb_pad, olen; 1281 int ret; 1282 unsigned char *p = 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 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 1291 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1292 1293 olen = ctx->len; 1294 1295 /* first comparison checks for overflow */ 1296 if( ilen + 11 < ilen || olen < ilen + 11 ) 1297 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1298 1299 nb_pad = olen - 3 - ilen; 1300 1301 *p++ = 0; 1302 if( mode == MBEDTLS_RSA_PUBLIC ) 1303 { 1304 if( f_rng == NULL ) 1305 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1306 1307 *p++ = MBEDTLS_RSA_CRYPT; 1308 1309 while( nb_pad-- > 0 ) 1310 { 1311 int rng_dl = 100; 1312 1313 do { 1314 ret = f_rng( p_rng, p, 1 ); 1315 } while( *p == 0 && --rng_dl && ret == 0 ); 1316 1317 /* Check if RNG failed to generate data */ 1318 if( rng_dl == 0 || ret != 0 ) 1319 return( MBEDTLS_ERR_RSA_RNG_FAILED + ret ); 1320 1321 p++; 1322 } 1323 } 1324 else 1325 { 1326 *p++ = MBEDTLS_RSA_SIGN; 1327 1328 while( nb_pad-- > 0 ) 1329 *p++ = 0xFF; 1330 } 1331 1332 *p++ = 0; 1333 memcpy( p, input, ilen ); 1334 1335 return( ( mode == MBEDTLS_RSA_PUBLIC ) 1336 ? mbedtls_rsa_public( ctx, output, output ) 1337 : mbedtls_rsa_private( ctx, f_rng, p_rng, output, output ) ); 1338 } 1339 #endif /* MBEDTLS_PKCS1_V15 */ 1340 1341 /* 1342 * Add the message padding, then do an RSA operation 1343 */ 1344 int mbedtls_rsa_pkcs1_encrypt( mbedtls_rsa_context *ctx, 1345 int (*f_rng)(void *, unsigned char *, size_t), 1346 void *p_rng, 1347 int mode, size_t ilen, 1348 const unsigned char *input, 1349 unsigned char *output ) 1350 { 1351 RSA_VALIDATE_RET( ctx != NULL ); 1352 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1353 mode == MBEDTLS_RSA_PUBLIC ); 1354 RSA_VALIDATE_RET( output != NULL ); 1355 RSA_VALIDATE_RET( input != NULL ); 1356 1357 switch( ctx->padding ) 1358 { 1359 #if defined(MBEDTLS_PKCS1_V15) 1360 case MBEDTLS_RSA_PKCS_V15: 1361 return mbedtls_rsa_rsaes_pkcs1_v15_encrypt( ctx, f_rng, p_rng, mode, ilen, 1362 input, output ); 1363 #endif 1364 1365 #if defined(MBEDTLS_PKCS1_V21) 1366 case MBEDTLS_RSA_PKCS_V21: 1367 return mbedtls_rsa_rsaes_oaep_encrypt( ctx, f_rng, p_rng, mode, NULL, 0, 1368 ilen, input, output ); 1369 #endif 1370 1371 default: 1372 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 1373 } 1374 } 1375 1376 #if defined(MBEDTLS_PKCS1_V21) 1377 /* 1378 * Implementation of the PKCS#1 v2.1 RSAES-OAEP-DECRYPT function 1379 */ 1380 int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx, 1381 int (*f_rng)(void *, unsigned char *, size_t), 1382 void *p_rng, 1383 int mode, 1384 const unsigned char *label, size_t label_len, 1385 size_t *olen, 1386 const unsigned char *input, 1387 unsigned char *output, 1388 size_t output_max_len ) 1389 { 1390 int ret; 1391 size_t ilen, i, pad_len; 1392 unsigned char *p, bad, pad_done; 1393 unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; 1394 unsigned char lhash[MBEDTLS_MD_MAX_SIZE]; 1395 unsigned int hlen; 1396 const mbedtls_md_info_t *md_info; 1397 mbedtls_md_context_t md_ctx; 1398 1399 RSA_VALIDATE_RET( ctx != NULL ); 1400 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1401 mode == MBEDTLS_RSA_PUBLIC ); 1402 RSA_VALIDATE_RET( output_max_len == 0 || output != NULL ); 1403 RSA_VALIDATE_RET( label_len == 0 || label != NULL ); 1404 RSA_VALIDATE_RET( input != NULL ); 1405 RSA_VALIDATE_RET( olen != NULL ); 1406 1407 /* 1408 * Parameters sanity checks 1409 */ 1410 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) 1411 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1412 1413 ilen = ctx->len; 1414 1415 if( ilen < 16 || ilen > sizeof( buf ) ) 1416 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1417 1418 md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id ); 1419 if( md_info == NULL ) 1420 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1421 1422 hlen = mbedtls_md_get_size( md_info ); 1423 1424 // checking for integer underflow 1425 if( 2 * hlen + 2 > ilen ) 1426 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1427 1428 /* 1429 * RSA operation 1430 */ 1431 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 1432 ? mbedtls_rsa_public( ctx, input, buf ) 1433 : mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf ); 1434 1435 if( ret != 0 ) 1436 goto cleanup; 1437 1438 /* 1439 * Unmask data and generate lHash 1440 */ 1441 mbedtls_md_init( &md_ctx ); 1442 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 1443 { 1444 mbedtls_md_free( &md_ctx ); 1445 goto cleanup; 1446 } 1447 1448 /* seed: Apply seedMask to maskedSeed */ 1449 if( ( ret = mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1, 1450 &md_ctx ) ) != 0 || 1451 /* DB: Apply dbMask to maskedDB */ 1452 ( ret = mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen, 1453 &md_ctx ) ) != 0 ) 1454 { 1455 mbedtls_md_free( &md_ctx ); 1456 goto cleanup; 1457 } 1458 1459 mbedtls_md_free( &md_ctx ); 1460 1461 /* Generate lHash */ 1462 if( ( ret = mbedtls_md( md_info, label, label_len, lhash ) ) != 0 ) 1463 goto cleanup; 1464 1465 /* 1466 * Check contents, in "constant-time" 1467 */ 1468 p = buf; 1469 bad = 0; 1470 1471 bad |= *p++; /* First byte must be 0 */ 1472 1473 p += hlen; /* Skip seed */ 1474 1475 /* Check lHash */ 1476 for( i = 0; i < hlen; i++ ) 1477 bad |= lhash[i] ^ *p++; 1478 1479 /* Get zero-padding len, but always read till end of buffer 1480 * (minus one, for the 01 byte) */ 1481 pad_len = 0; 1482 pad_done = 0; 1483 for( i = 0; i < ilen - 2 * hlen - 2; i++ ) 1484 { 1485 pad_done |= p[i]; 1486 pad_len += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1; 1487 } 1488 1489 p += pad_len; 1490 bad |= *p++ ^ 0x01; 1491 1492 /* 1493 * The only information "leaked" is whether the padding was correct or not 1494 * (eg, no data is copied if it was not correct). This meets the 1495 * recommendations in PKCS#1 v2.2: an opponent cannot distinguish between 1496 * the different error conditions. 1497 */ 1498 if( bad != 0 ) 1499 { 1500 ret = MBEDTLS_ERR_RSA_INVALID_PADDING; 1501 goto cleanup; 1502 } 1503 1504 if( ilen - ( p - buf ) > output_max_len ) 1505 { 1506 ret = MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE; 1507 goto cleanup; 1508 } 1509 1510 *olen = ilen - (p - buf); 1511 memcpy( output, p, *olen ); 1512 ret = 0; 1513 1514 cleanup: 1515 mbedtls_platform_zeroize( buf, sizeof( buf ) ); 1516 mbedtls_platform_zeroize( lhash, sizeof( lhash ) ); 1517 1518 return( ret ); 1519 } 1520 #endif /* MBEDTLS_PKCS1_V21 */ 1521 1522 #if defined(MBEDTLS_PKCS1_V15) 1523 /** Turn zero-or-nonzero into zero-or-all-bits-one, without branches. 1524 * 1525 * \param value The value to analyze. 1526 * \return Zero if \p value is zero, otherwise all-bits-one. 1527 */ 1528 static unsigned all_or_nothing_int( unsigned value ) 1529 { 1530 /* MSVC has a warning about unary minus on unsigned, but this is 1531 * well-defined and precisely what we want to do here */ 1532 #if defined(_MSC_VER) 1533 #pragma warning( push ) 1534 #pragma warning( disable : 4146 ) 1535 #endif 1536 return( - ( ( value | - value ) >> ( sizeof( value ) * 8 - 1 ) ) ); 1537 #if defined(_MSC_VER) 1538 #pragma warning( pop ) 1539 #endif 1540 } 1541 1542 /** Check whether a size is out of bounds, without branches. 1543 * 1544 * This is equivalent to `size > max`, but is likely to be compiled to 1545 * to code using bitwise operation rather than a branch. 1546 * 1547 * \param size Size to check. 1548 * \param max Maximum desired value for \p size. 1549 * \return \c 0 if `size <= max`. 1550 * \return \c 1 if `size > max`. 1551 */ 1552 static unsigned size_greater_than( size_t size, size_t max ) 1553 { 1554 /* Return the sign bit (1 for negative) of (max - size). */ 1555 return( ( max - size ) >> ( sizeof( size_t ) * 8 - 1 ) ); 1556 } 1557 1558 /** Choose between two integer values, without branches. 1559 * 1560 * This is equivalent to `cond ? if1 : if0`, but is likely to be compiled 1561 * to code using bitwise operation rather than a branch. 1562 * 1563 * \param cond Condition to test. 1564 * \param if1 Value to use if \p cond is nonzero. 1565 * \param if0 Value to use if \p cond is zero. 1566 * \return \c if1 if \p cond is nonzero, otherwise \c if0. 1567 */ 1568 static unsigned if_int( unsigned cond, unsigned if1, unsigned if0 ) 1569 { 1570 unsigned mask = all_or_nothing_int( cond ); 1571 return( ( mask & if1 ) | (~mask & if0 ) ); 1572 } 1573 1574 /** Shift some data towards the left inside a buffer without leaking 1575 * the length of the data through side channels. 1576 * 1577 * `mem_move_to_left(start, total, offset)` is functionally equivalent to 1578 * ``` 1579 * memmove(start, start + offset, total - offset); 1580 * memset(start + offset, 0, total - offset); 1581 * ``` 1582 * but it strives to use a memory access pattern (and thus total timing) 1583 * that does not depend on \p offset. This timing independence comes at 1584 * the expense of performance. 1585 * 1586 * \param start Pointer to the start of the buffer. 1587 * \param total Total size of the buffer. 1588 * \param offset Offset from which to copy \p total - \p offset bytes. 1589 */ 1590 static void mem_move_to_left( void *start, 1591 size_t total, 1592 size_t offset ) 1593 { 1594 volatile unsigned char *buf = start; 1595 size_t i, n; 1596 if( total == 0 ) 1597 return; 1598 for( i = 0; i < total; i++ ) 1599 { 1600 unsigned no_op = size_greater_than( total - offset, i ); 1601 /* The first `total - offset` passes are a no-op. The last 1602 * `offset` passes shift the data one byte to the left and 1603 * zero out the last byte. */ 1604 for( n = 0; n < total - 1; n++ ) 1605 { 1606 unsigned char current = buf[n]; 1607 unsigned char next = buf[n+1]; 1608 buf[n] = if_int( no_op, current, next ); 1609 } 1610 buf[total-1] = if_int( no_op, buf[total-1], 0 ); 1611 } 1612 } 1613 1614 /* 1615 * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-DECRYPT function 1616 */ 1617 int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx, 1618 int (*f_rng)(void *, unsigned char *, size_t), 1619 void *p_rng, 1620 int mode, size_t *olen, 1621 const unsigned char *input, 1622 unsigned char *output, 1623 size_t output_max_len ) 1624 { 1625 int ret; 1626 size_t ilen, i, plaintext_max_size; 1627 unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; 1628 /* The following variables take sensitive values: their value must 1629 * not leak into the observable behavior of the function other than 1630 * the designated outputs (output, olen, return value). Otherwise 1631 * this would open the execution of the function to 1632 * side-channel-based variants of the Bleichenbacher padding oracle 1633 * attack. Potential side channels include overall timing, memory 1634 * access patterns (especially visible to an adversary who has access 1635 * to a shared memory cache), and branches (especially visible to 1636 * an adversary who has access to a shared code cache or to a shared 1637 * branch predictor). */ 1638 size_t pad_count = 0; 1639 unsigned bad = 0; 1640 unsigned char pad_done = 0; 1641 size_t plaintext_size = 0; 1642 unsigned output_too_large; 1643 1644 RSA_VALIDATE_RET( ctx != NULL ); 1645 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1646 mode == MBEDTLS_RSA_PUBLIC ); 1647 RSA_VALIDATE_RET( output_max_len == 0 || output != NULL ); 1648 RSA_VALIDATE_RET( input != NULL ); 1649 RSA_VALIDATE_RET( olen != NULL ); 1650 1651 ilen = ctx->len; 1652 plaintext_max_size = ( output_max_len > ilen - 11 ? 1653 ilen - 11 : 1654 output_max_len ); 1655 1656 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 1657 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1658 1659 if( ilen < 16 || ilen > sizeof( buf ) ) 1660 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1661 1662 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 1663 ? mbedtls_rsa_public( ctx, input, buf ) 1664 : mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf ); 1665 1666 if( ret != 0 ) 1667 goto cleanup; 1668 1669 /* Check and get padding length in constant time and constant 1670 * memory trace. The first byte must be 0. */ 1671 bad |= buf[0]; 1672 1673 if( mode == MBEDTLS_RSA_PRIVATE ) 1674 { 1675 /* Decode EME-PKCS1-v1_5 padding: 0x00 || 0x02 || PS || 0x00 1676 * where PS must be at least 8 nonzero bytes. */ 1677 bad |= buf[1] ^ MBEDTLS_RSA_CRYPT; 1678 1679 /* Read the whole buffer. Set pad_done to nonzero if we find 1680 * the 0x00 byte and remember the padding length in pad_count. */ 1681 for( i = 2; i < ilen; i++ ) 1682 { 1683 pad_done |= ((buf[i] | (unsigned char)-buf[i]) >> 7) ^ 1; 1684 pad_count += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1; 1685 } 1686 } 1687 else 1688 { 1689 /* Decode EMSA-PKCS1-v1_5 padding: 0x00 || 0x01 || PS || 0x00 1690 * where PS must be at least 8 bytes with the value 0xFF. */ 1691 bad |= buf[1] ^ MBEDTLS_RSA_SIGN; 1692 1693 /* Read the whole buffer. Set pad_done to nonzero if we find 1694 * the 0x00 byte and remember the padding length in pad_count. 1695 * If there's a non-0xff byte in the padding, the padding is bad. */ 1696 for( i = 2; i < ilen; i++ ) 1697 { 1698 pad_done |= if_int( buf[i], 0, 1 ); 1699 pad_count += if_int( pad_done, 0, 1 ); 1700 bad |= if_int( pad_done, 0, buf[i] ^ 0xFF ); 1701 } 1702 } 1703 1704 /* If pad_done is still zero, there's no data, only unfinished padding. */ 1705 bad |= if_int( pad_done, 0, 1 ); 1706 1707 /* There must be at least 8 bytes of padding. */ 1708 bad |= size_greater_than( 8, pad_count ); 1709 1710 /* If the padding is valid, set plaintext_size to the number of 1711 * remaining bytes after stripping the padding. If the padding 1712 * is invalid, avoid leaking this fact through the size of the 1713 * output: use the maximum message size that fits in the output 1714 * buffer. Do it without branches to avoid leaking the padding 1715 * validity through timing. RSA keys are small enough that all the 1716 * size_t values involved fit in unsigned int. */ 1717 plaintext_size = if_int( bad, 1718 (unsigned) plaintext_max_size, 1719 (unsigned) ( ilen - pad_count - 3 ) ); 1720 1721 /* Set output_too_large to 0 if the plaintext fits in the output 1722 * buffer and to 1 otherwise. */ 1723 output_too_large = size_greater_than( plaintext_size, 1724 plaintext_max_size ); 1725 1726 /* Set ret without branches to avoid timing attacks. Return: 1727 * - INVALID_PADDING if the padding is bad (bad != 0). 1728 * - OUTPUT_TOO_LARGE if the padding is good but the decrypted 1729 * plaintext does not fit in the output buffer. 1730 * - 0 if the padding is correct. */ 1731 ret = - (int) if_int( bad, - MBEDTLS_ERR_RSA_INVALID_PADDING, 1732 if_int( output_too_large, - MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE, 1733 0 ) ); 1734 1735 /* If the padding is bad or the plaintext is too large, zero the 1736 * data that we're about to copy to the output buffer. 1737 * We need to copy the same amount of data 1738 * from the same buffer whether the padding is good or not to 1739 * avoid leaking the padding validity through overall timing or 1740 * through memory or cache access patterns. */ 1741 bad = all_or_nothing_int( bad | output_too_large ); 1742 for( i = 11; i < ilen; i++ ) 1743 buf[i] &= ~bad; 1744 1745 /* If the plaintext is too large, truncate it to the buffer size. 1746 * Copy anyway to avoid revealing the length through timing, because 1747 * revealing the length is as bad as revealing the padding validity 1748 * for a Bleichenbacher attack. */ 1749 plaintext_size = if_int( output_too_large, 1750 (unsigned) plaintext_max_size, 1751 (unsigned) plaintext_size ); 1752 1753 /* Move the plaintext to the leftmost position where it can start in 1754 * the working buffer, i.e. make it start plaintext_max_size from 1755 * the end of the buffer. Do this with a memory access trace that 1756 * does not depend on the plaintext size. After this move, the 1757 * starting location of the plaintext is no longer sensitive 1758 * information. */ 1759 mem_move_to_left( buf + ilen - plaintext_max_size, 1760 plaintext_max_size, 1761 plaintext_max_size - plaintext_size ); 1762 1763 /* Finally copy the decrypted plaintext plus trailing zeros 1764 * into the output buffer. */ 1765 memcpy( output, buf + ilen - plaintext_max_size, plaintext_max_size ); 1766 1767 /* Report the amount of data we copied to the output buffer. In case 1768 * of errors (bad padding or output too large), the value of *olen 1769 * when this function returns is not specified. Making it equivalent 1770 * to the good case limits the risks of leaking the padding validity. */ 1771 *olen = plaintext_size; 1772 1773 cleanup: 1774 mbedtls_platform_zeroize( buf, sizeof( buf ) ); 1775 1776 return( ret ); 1777 } 1778 #endif /* MBEDTLS_PKCS1_V15 */ 1779 1780 /* 1781 * Do an RSA operation, then remove the message padding 1782 */ 1783 int mbedtls_rsa_pkcs1_decrypt( mbedtls_rsa_context *ctx, 1784 int (*f_rng)(void *, unsigned char *, size_t), 1785 void *p_rng, 1786 int mode, size_t *olen, 1787 const unsigned char *input, 1788 unsigned char *output, 1789 size_t output_max_len) 1790 { 1791 RSA_VALIDATE_RET( ctx != NULL ); 1792 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1793 mode == MBEDTLS_RSA_PUBLIC ); 1794 RSA_VALIDATE_RET( output_max_len == 0 || output != NULL ); 1795 RSA_VALIDATE_RET( input != NULL ); 1796 RSA_VALIDATE_RET( olen != NULL ); 1797 1798 switch( ctx->padding ) 1799 { 1800 #if defined(MBEDTLS_PKCS1_V15) 1801 case MBEDTLS_RSA_PKCS_V15: 1802 return mbedtls_rsa_rsaes_pkcs1_v15_decrypt( ctx, f_rng, p_rng, mode, olen, 1803 input, output, output_max_len ); 1804 #endif 1805 1806 #if defined(MBEDTLS_PKCS1_V21) 1807 case MBEDTLS_RSA_PKCS_V21: 1808 return mbedtls_rsa_rsaes_oaep_decrypt( ctx, f_rng, p_rng, mode, NULL, 0, 1809 olen, input, output, 1810 output_max_len ); 1811 #endif 1812 1813 default: 1814 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 1815 } 1816 } 1817 1818 #if defined(MBEDTLS_PKCS1_V21) 1819 /* 1820 * Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function 1821 */ 1822 int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx, 1823 int (*f_rng)(void *, unsigned char *, size_t), 1824 void *p_rng, 1825 int mode, 1826 mbedtls_md_type_t md_alg, 1827 unsigned int hashlen, 1828 const unsigned char *hash, 1829 unsigned char *sig ) 1830 { 1831 size_t olen; 1832 unsigned char *p = sig; 1833 unsigned char salt[MBEDTLS_MD_MAX_SIZE]; 1834 size_t slen, min_slen, hlen, offset = 0; 1835 int ret; 1836 size_t msb; 1837 const mbedtls_md_info_t *md_info; 1838 mbedtls_md_context_t md_ctx; 1839 RSA_VALIDATE_RET( ctx != NULL ); 1840 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 1841 mode == MBEDTLS_RSA_PUBLIC ); 1842 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 1843 hashlen == 0 ) || 1844 hash != NULL ); 1845 RSA_VALIDATE_RET( sig != NULL ); 1846 1847 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) 1848 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1849 1850 if( f_rng == NULL ) 1851 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1852 1853 olen = ctx->len; 1854 1855 if( md_alg != MBEDTLS_MD_NONE ) 1856 { 1857 /* Gather length of hash to sign */ 1858 md_info = mbedtls_md_info_from_type( md_alg ); 1859 if( md_info == NULL ) 1860 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1861 1862 hashlen = mbedtls_md_get_size( md_info ); 1863 } 1864 1865 md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id ); 1866 if( md_info == NULL ) 1867 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1868 1869 hlen = mbedtls_md_get_size( md_info ); 1870 1871 /* Calculate the largest possible salt length. Normally this is the hash 1872 * length, which is the maximum length the salt can have. If there is not 1873 * enough room, use the maximum salt length that fits. The constraint is 1874 * that the hash length plus the salt length plus 2 bytes must be at most 1875 * the key length. This complies with FIPS 186-4 §5.5 (e) and RFC 8017 1876 * (PKCS#1 v2.2) §9.1.1 step 3. */ 1877 min_slen = hlen - 2; 1878 if( olen < hlen + min_slen + 2 ) 1879 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1880 else if( olen >= hlen + hlen + 2 ) 1881 slen = hlen; 1882 else 1883 slen = olen - hlen - 2; 1884 1885 memset( sig, 0, olen ); 1886 1887 /* Generate salt of length slen */ 1888 if( ( ret = f_rng( p_rng, salt, slen ) ) != 0 ) 1889 return( MBEDTLS_ERR_RSA_RNG_FAILED + ret ); 1890 1891 /* Note: EMSA-PSS encoding is over the length of N - 1 bits */ 1892 msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; 1893 p += olen - hlen - slen - 2; 1894 *p++ = 0x01; 1895 memcpy( p, salt, slen ); 1896 p += slen; 1897 1898 mbedtls_md_init( &md_ctx ); 1899 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 1900 goto exit; 1901 1902 /* Generate H = Hash( M' ) */ 1903 if( ( ret = mbedtls_md_starts( &md_ctx ) ) != 0 ) 1904 goto exit; 1905 if( ( ret = mbedtls_md_update( &md_ctx, p, 8 ) ) != 0 ) 1906 goto exit; 1907 if( ( ret = mbedtls_md_update( &md_ctx, hash, hashlen ) ) != 0 ) 1908 goto exit; 1909 if( ( ret = mbedtls_md_update( &md_ctx, salt, slen ) ) != 0 ) 1910 goto exit; 1911 if( ( ret = mbedtls_md_finish( &md_ctx, p ) ) != 0 ) 1912 goto exit; 1913 1914 /* Compensate for boundary condition when applying mask */ 1915 if( msb % 8 == 0 ) 1916 offset = 1; 1917 1918 /* maskedDB: Apply dbMask to DB */ 1919 if( ( ret = mgf_mask( sig + offset, olen - hlen - 1 - offset, p, hlen, 1920 &md_ctx ) ) != 0 ) 1921 goto exit; 1922 1923 msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; 1924 sig[0] &= 0xFF >> ( olen * 8 - msb ); 1925 1926 p += hlen; 1927 *p++ = 0xBC; 1928 1929 mbedtls_platform_zeroize( salt, sizeof( salt ) ); 1930 1931 exit: 1932 mbedtls_md_free( &md_ctx ); 1933 1934 if( ret != 0 ) 1935 return( ret ); 1936 1937 return( ( mode == MBEDTLS_RSA_PUBLIC ) 1938 ? mbedtls_rsa_public( ctx, sig, sig ) 1939 : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig ) ); 1940 } 1941 #endif /* MBEDTLS_PKCS1_V21 */ 1942 1943 #if defined(MBEDTLS_PKCS1_V15) 1944 /* 1945 * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-V1_5-SIGN function 1946 */ 1947 1948 /* Construct a PKCS v1.5 encoding of a hashed message 1949 * 1950 * This is used both for signature generation and verification. 1951 * 1952 * Parameters: 1953 * - md_alg: Identifies the hash algorithm used to generate the given hash; 1954 * MBEDTLS_MD_NONE if raw data is signed. 1955 * - hashlen: Length of hash in case hashlen is MBEDTLS_MD_NONE. 1956 * - hash: Buffer containing the hashed message or the raw data. 1957 * - dst_len: Length of the encoded message. 1958 * - dst: Buffer to hold the encoded message. 1959 * 1960 * Assumptions: 1961 * - hash has size hashlen if md_alg == MBEDTLS_MD_NONE. 1962 * - hash has size corresponding to md_alg if md_alg != MBEDTLS_MD_NONE. 1963 * - dst points to a buffer of size at least dst_len. 1964 * 1965 */ 1966 static int rsa_rsassa_pkcs1_v15_encode( mbedtls_md_type_t md_alg, 1967 unsigned int hashlen, 1968 const unsigned char *hash, 1969 size_t dst_len, 1970 unsigned char *dst ) 1971 { 1972 size_t oid_size = 0; 1973 size_t nb_pad = dst_len; 1974 unsigned char *p = dst; 1975 const char *oid = NULL; 1976 1977 /* Are we signing hashed or raw data? */ 1978 if( md_alg != MBEDTLS_MD_NONE ) 1979 { 1980 const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg ); 1981 if( md_info == NULL ) 1982 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1983 1984 if( mbedtls_oid_get_oid_by_md( md_alg, &oid, &oid_size ) != 0 ) 1985 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1986 1987 hashlen = mbedtls_md_get_size( md_info ); 1988 1989 /* Double-check that 8 + hashlen + oid_size can be used as a 1990 * 1-byte ASN.1 length encoding and that there's no overflow. */ 1991 if( 8 + hashlen + oid_size >= 0x80 || 1992 10 + hashlen < hashlen || 1993 10 + hashlen + oid_size < 10 + hashlen ) 1994 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 1995 1996 /* 1997 * Static bounds check: 1998 * - Need 10 bytes for five tag-length pairs. 1999 * (Insist on 1-byte length encodings to protect against variants of 2000 * Bleichenbacher's forgery attack against lax PKCS#1v1.5 verification) 2001 * - Need hashlen bytes for hash 2002 * - Need oid_size bytes for hash alg OID. 2003 */ 2004 if( nb_pad < 10 + hashlen + oid_size ) 2005 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2006 nb_pad -= 10 + hashlen + oid_size; 2007 } 2008 else 2009 { 2010 if( nb_pad < hashlen ) 2011 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2012 2013 nb_pad -= hashlen; 2014 } 2015 2016 /* Need space for signature header and padding delimiter (3 bytes), 2017 * and 8 bytes for the minimal padding */ 2018 if( nb_pad < 3 + 8 ) 2019 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2020 nb_pad -= 3; 2021 2022 /* Now nb_pad is the amount of memory to be filled 2023 * with padding, and at least 8 bytes long. */ 2024 2025 /* Write signature header and padding */ 2026 *p++ = 0; 2027 *p++ = MBEDTLS_RSA_SIGN; 2028 memset( p, 0xFF, nb_pad ); 2029 p += nb_pad; 2030 *p++ = 0; 2031 2032 /* Are we signing raw data? */ 2033 if( md_alg == MBEDTLS_MD_NONE ) 2034 { 2035 memcpy( p, hash, hashlen ); 2036 return( 0 ); 2037 } 2038 2039 /* Signing hashed data, add corresponding ASN.1 structure 2040 * 2041 * DigestInfo ::= SEQUENCE { 2042 * digestAlgorithm DigestAlgorithmIdentifier, 2043 * digest Digest } 2044 * DigestAlgorithmIdentifier ::= AlgorithmIdentifier 2045 * Digest ::= OCTET STRING 2046 * 2047 * Schematic: 2048 * TAG-SEQ + LEN [ TAG-SEQ + LEN [ TAG-OID + LEN [ OID ] 2049 * TAG-NULL + LEN [ NULL ] ] 2050 * TAG-OCTET + LEN [ HASH ] ] 2051 */ 2052 *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED; 2053 *p++ = (unsigned char)( 0x08 + oid_size + hashlen ); 2054 *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED; 2055 *p++ = (unsigned char)( 0x04 + oid_size ); 2056 *p++ = MBEDTLS_ASN1_OID; 2057 *p++ = (unsigned char) oid_size; 2058 memcpy( p, oid, oid_size ); 2059 p += oid_size; 2060 *p++ = MBEDTLS_ASN1_NULL; 2061 *p++ = 0x00; 2062 *p++ = MBEDTLS_ASN1_OCTET_STRING; 2063 *p++ = (unsigned char) hashlen; 2064 memcpy( p, hash, hashlen ); 2065 p += hashlen; 2066 2067 /* Just a sanity-check, should be automatic 2068 * after the initial bounds check. */ 2069 if( p != dst + dst_len ) 2070 { 2071 mbedtls_platform_zeroize( dst, dst_len ); 2072 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2073 } 2074 2075 return( 0 ); 2076 } 2077 2078 /* 2079 * Do an RSA operation to sign the message digest 2080 */ 2081 int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx, 2082 int (*f_rng)(void *, unsigned char *, size_t), 2083 void *p_rng, 2084 int mode, 2085 mbedtls_md_type_t md_alg, 2086 unsigned int hashlen, 2087 const unsigned char *hash, 2088 unsigned char *sig ) 2089 { 2090 int ret; 2091 unsigned char *sig_try = NULL, *verif = NULL; 2092 2093 RSA_VALIDATE_RET( ctx != NULL ); 2094 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2095 mode == MBEDTLS_RSA_PUBLIC ); 2096 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2097 hashlen == 0 ) || 2098 hash != NULL ); 2099 RSA_VALIDATE_RET( sig != NULL ); 2100 2101 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 2102 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2103 2104 /* 2105 * Prepare PKCS1-v1.5 encoding (padding and hash identifier) 2106 */ 2107 2108 if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash, 2109 ctx->len, sig ) ) != 0 ) 2110 return( ret ); 2111 2112 /* 2113 * Call respective RSA primitive 2114 */ 2115 2116 if( mode == MBEDTLS_RSA_PUBLIC ) 2117 { 2118 /* Skip verification on a public key operation */ 2119 return( mbedtls_rsa_public( ctx, sig, sig ) ); 2120 } 2121 2122 /* Private key operation 2123 * 2124 * In order to prevent Lenstra's attack, make the signature in a 2125 * temporary buffer and check it before returning it. 2126 */ 2127 2128 sig_try = mbedtls_calloc( 1, ctx->len ); 2129 if( sig_try == NULL ) 2130 return( MBEDTLS_ERR_MPI_ALLOC_FAILED ); 2131 2132 verif = mbedtls_calloc( 1, ctx->len ); 2133 if( verif == NULL ) 2134 { 2135 mbedtls_free( sig_try ); 2136 return( MBEDTLS_ERR_MPI_ALLOC_FAILED ); 2137 } 2138 2139 MBEDTLS_MPI_CHK( mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig_try ) ); 2140 MBEDTLS_MPI_CHK( mbedtls_rsa_public( ctx, sig_try, verif ) ); 2141 2142 if( mbedtls_safer_memcmp( verif, sig, ctx->len ) != 0 ) 2143 { 2144 ret = MBEDTLS_ERR_RSA_PRIVATE_FAILED; 2145 goto cleanup; 2146 } 2147 2148 memcpy( sig, sig_try, ctx->len ); 2149 2150 cleanup: 2151 mbedtls_free( sig_try ); 2152 mbedtls_free( verif ); 2153 2154 return( ret ); 2155 } 2156 #endif /* MBEDTLS_PKCS1_V15 */ 2157 2158 /* 2159 * Do an RSA operation to sign the message digest 2160 */ 2161 int mbedtls_rsa_pkcs1_sign( mbedtls_rsa_context *ctx, 2162 int (*f_rng)(void *, unsigned char *, size_t), 2163 void *p_rng, 2164 int mode, 2165 mbedtls_md_type_t md_alg, 2166 unsigned int hashlen, 2167 const unsigned char *hash, 2168 unsigned char *sig ) 2169 { 2170 RSA_VALIDATE_RET( ctx != NULL ); 2171 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2172 mode == MBEDTLS_RSA_PUBLIC ); 2173 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2174 hashlen == 0 ) || 2175 hash != NULL ); 2176 RSA_VALIDATE_RET( sig != NULL ); 2177 2178 switch( ctx->padding ) 2179 { 2180 #if defined(MBEDTLS_PKCS1_V15) 2181 case MBEDTLS_RSA_PKCS_V15: 2182 return mbedtls_rsa_rsassa_pkcs1_v15_sign( ctx, f_rng, p_rng, mode, md_alg, 2183 hashlen, hash, sig ); 2184 #endif 2185 2186 #if defined(MBEDTLS_PKCS1_V21) 2187 case MBEDTLS_RSA_PKCS_V21: 2188 return mbedtls_rsa_rsassa_pss_sign( ctx, f_rng, p_rng, mode, md_alg, 2189 hashlen, hash, sig ); 2190 #endif 2191 2192 default: 2193 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 2194 } 2195 } 2196 2197 #if defined(MBEDTLS_PKCS1_V21) 2198 /* 2199 * Implementation of the PKCS#1 v2.1 RSASSA-PSS-VERIFY function 2200 */ 2201 int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx, 2202 int (*f_rng)(void *, unsigned char *, size_t), 2203 void *p_rng, 2204 int mode, 2205 mbedtls_md_type_t md_alg, 2206 unsigned int hashlen, 2207 const unsigned char *hash, 2208 mbedtls_md_type_t mgf1_hash_id, 2209 int expected_salt_len, 2210 const unsigned char *sig ) 2211 { 2212 int ret; 2213 size_t siglen; 2214 unsigned char *p; 2215 unsigned char *hash_start; 2216 unsigned char result[MBEDTLS_MD_MAX_SIZE]; 2217 unsigned char zeros[8]; 2218 unsigned int hlen; 2219 size_t observed_salt_len, msb; 2220 const mbedtls_md_info_t *md_info; 2221 mbedtls_md_context_t md_ctx; 2222 unsigned char buf[MBEDTLS_MPI_MAX_SIZE]; 2223 2224 RSA_VALIDATE_RET( ctx != NULL ); 2225 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2226 mode == MBEDTLS_RSA_PUBLIC ); 2227 RSA_VALIDATE_RET( sig != NULL ); 2228 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2229 hashlen == 0 ) || 2230 hash != NULL ); 2231 2232 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 ) 2233 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2234 2235 siglen = ctx->len; 2236 2237 if( siglen < 16 || siglen > sizeof( buf ) ) 2238 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2239 2240 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 2241 ? mbedtls_rsa_public( ctx, sig, buf ) 2242 : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, buf ); 2243 2244 if( ret != 0 ) 2245 return( ret ); 2246 2247 p = buf; 2248 2249 if( buf[siglen - 1] != 0xBC ) 2250 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 2251 2252 if( md_alg != MBEDTLS_MD_NONE ) 2253 { 2254 /* Gather length of hash to sign */ 2255 md_info = mbedtls_md_info_from_type( md_alg ); 2256 if( md_info == NULL ) 2257 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2258 2259 hashlen = mbedtls_md_get_size( md_info ); 2260 } 2261 2262 md_info = mbedtls_md_info_from_type( mgf1_hash_id ); 2263 if( md_info == NULL ) 2264 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2265 2266 hlen = mbedtls_md_get_size( md_info ); 2267 2268 memset( zeros, 0, 8 ); 2269 2270 /* 2271 * Note: EMSA-PSS verification is over the length of N - 1 bits 2272 */ 2273 msb = mbedtls_mpi_bitlen( &ctx->N ) - 1; 2274 2275 if( buf[0] >> ( 8 - siglen * 8 + msb ) ) 2276 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2277 2278 /* Compensate for boundary condition when applying mask */ 2279 if( msb % 8 == 0 ) 2280 { 2281 p++; 2282 siglen -= 1; 2283 } 2284 2285 if( siglen < hlen + 2 ) 2286 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2287 hash_start = p + siglen - hlen - 1; 2288 2289 mbedtls_md_init( &md_ctx ); 2290 if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) 2291 goto exit; 2292 2293 ret = mgf_mask( p, siglen - hlen - 1, hash_start, hlen, &md_ctx ); 2294 if( ret != 0 ) 2295 goto exit; 2296 2297 buf[0] &= 0xFF >> ( siglen * 8 - msb ); 2298 2299 while( p < hash_start - 1 && *p == 0 ) 2300 p++; 2301 2302 if( *p++ != 0x01 ) 2303 { 2304 ret = MBEDTLS_ERR_RSA_INVALID_PADDING; 2305 goto exit; 2306 } 2307 2308 observed_salt_len = hash_start - p; 2309 2310 if( expected_salt_len != MBEDTLS_RSA_SALT_LEN_ANY && 2311 observed_salt_len != (size_t) expected_salt_len ) 2312 { 2313 ret = MBEDTLS_ERR_RSA_INVALID_PADDING; 2314 goto exit; 2315 } 2316 2317 /* 2318 * Generate H = Hash( M' ) 2319 */ 2320 ret = mbedtls_md_starts( &md_ctx ); 2321 if ( ret != 0 ) 2322 goto exit; 2323 ret = mbedtls_md_update( &md_ctx, zeros, 8 ); 2324 if ( ret != 0 ) 2325 goto exit; 2326 ret = mbedtls_md_update( &md_ctx, hash, hashlen ); 2327 if ( ret != 0 ) 2328 goto exit; 2329 ret = mbedtls_md_update( &md_ctx, p, observed_salt_len ); 2330 if ( ret != 0 ) 2331 goto exit; 2332 ret = mbedtls_md_finish( &md_ctx, result ); 2333 if ( ret != 0 ) 2334 goto exit; 2335 2336 if( memcmp( hash_start, result, hlen ) != 0 ) 2337 { 2338 ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; 2339 goto exit; 2340 } 2341 2342 exit: 2343 mbedtls_md_free( &md_ctx ); 2344 2345 return( ret ); 2346 } 2347 2348 /* 2349 * Simplified PKCS#1 v2.1 RSASSA-PSS-VERIFY function 2350 */ 2351 int mbedtls_rsa_rsassa_pss_verify( mbedtls_rsa_context *ctx, 2352 int (*f_rng)(void *, unsigned char *, size_t), 2353 void *p_rng, 2354 int mode, 2355 mbedtls_md_type_t md_alg, 2356 unsigned int hashlen, 2357 const unsigned char *hash, 2358 const unsigned char *sig ) 2359 { 2360 mbedtls_md_type_t mgf1_hash_id; 2361 RSA_VALIDATE_RET( ctx != NULL ); 2362 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2363 mode == MBEDTLS_RSA_PUBLIC ); 2364 RSA_VALIDATE_RET( sig != NULL ); 2365 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2366 hashlen == 0 ) || 2367 hash != NULL ); 2368 2369 mgf1_hash_id = ( ctx->hash_id != MBEDTLS_MD_NONE ) 2370 ? (mbedtls_md_type_t) ctx->hash_id 2371 : md_alg; 2372 2373 return( mbedtls_rsa_rsassa_pss_verify_ext( ctx, f_rng, p_rng, mode, 2374 md_alg, hashlen, hash, 2375 mgf1_hash_id, MBEDTLS_RSA_SALT_LEN_ANY, 2376 sig ) ); 2377 2378 } 2379 #endif /* MBEDTLS_PKCS1_V21 */ 2380 2381 #if defined(MBEDTLS_PKCS1_V15) 2382 /* 2383 * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-v1_5-VERIFY function 2384 */ 2385 int mbedtls_rsa_rsassa_pkcs1_v15_verify( mbedtls_rsa_context *ctx, 2386 int (*f_rng)(void *, unsigned char *, size_t), 2387 void *p_rng, 2388 int mode, 2389 mbedtls_md_type_t md_alg, 2390 unsigned int hashlen, 2391 const unsigned char *hash, 2392 const unsigned char *sig ) 2393 { 2394 int ret = 0; 2395 size_t sig_len; 2396 unsigned char *encoded = NULL, *encoded_expected = NULL; 2397 2398 RSA_VALIDATE_RET( ctx != NULL ); 2399 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2400 mode == MBEDTLS_RSA_PUBLIC ); 2401 RSA_VALIDATE_RET( sig != NULL ); 2402 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2403 hashlen == 0 ) || 2404 hash != NULL ); 2405 2406 sig_len = ctx->len; 2407 2408 if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 ) 2409 return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA ); 2410 2411 /* 2412 * Prepare expected PKCS1 v1.5 encoding of hash. 2413 */ 2414 2415 if( ( encoded = mbedtls_calloc( 1, sig_len ) ) == NULL || 2416 ( encoded_expected = mbedtls_calloc( 1, sig_len ) ) == NULL ) 2417 { 2418 ret = MBEDTLS_ERR_MPI_ALLOC_FAILED; 2419 goto cleanup; 2420 } 2421 2422 if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash, sig_len, 2423 encoded_expected ) ) != 0 ) 2424 goto cleanup; 2425 2426 /* 2427 * Apply RSA primitive to get what should be PKCS1 encoded hash. 2428 */ 2429 2430 ret = ( mode == MBEDTLS_RSA_PUBLIC ) 2431 ? mbedtls_rsa_public( ctx, sig, encoded ) 2432 : mbedtls_rsa_private( ctx, f_rng, p_rng, sig, encoded ); 2433 if( ret != 0 ) 2434 goto cleanup; 2435 2436 /* 2437 * Compare 2438 */ 2439 2440 if( ( ret = mbedtls_safer_memcmp( encoded, encoded_expected, 2441 sig_len ) ) != 0 ) 2442 { 2443 ret = MBEDTLS_ERR_RSA_VERIFY_FAILED; 2444 goto cleanup; 2445 } 2446 2447 cleanup: 2448 2449 if( encoded != NULL ) 2450 { 2451 mbedtls_platform_zeroize( encoded, sig_len ); 2452 mbedtls_free( encoded ); 2453 } 2454 2455 if( encoded_expected != NULL ) 2456 { 2457 mbedtls_platform_zeroize( encoded_expected, sig_len ); 2458 mbedtls_free( encoded_expected ); 2459 } 2460 2461 return( ret ); 2462 } 2463 #endif /* MBEDTLS_PKCS1_V15 */ 2464 2465 /* 2466 * Do an RSA operation and check the message digest 2467 */ 2468 int mbedtls_rsa_pkcs1_verify( mbedtls_rsa_context *ctx, 2469 int (*f_rng)(void *, unsigned char *, size_t), 2470 void *p_rng, 2471 int mode, 2472 mbedtls_md_type_t md_alg, 2473 unsigned int hashlen, 2474 const unsigned char *hash, 2475 const unsigned char *sig ) 2476 { 2477 RSA_VALIDATE_RET( ctx != NULL ); 2478 RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE || 2479 mode == MBEDTLS_RSA_PUBLIC ); 2480 RSA_VALIDATE_RET( sig != NULL ); 2481 RSA_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && 2482 hashlen == 0 ) || 2483 hash != NULL ); 2484 2485 switch( ctx->padding ) 2486 { 2487 #if defined(MBEDTLS_PKCS1_V15) 2488 case MBEDTLS_RSA_PKCS_V15: 2489 return mbedtls_rsa_rsassa_pkcs1_v15_verify( ctx, f_rng, p_rng, mode, md_alg, 2490 hashlen, hash, sig ); 2491 #endif 2492 2493 #if defined(MBEDTLS_PKCS1_V21) 2494 case MBEDTLS_RSA_PKCS_V21: 2495 return mbedtls_rsa_rsassa_pss_verify( ctx, f_rng, p_rng, mode, md_alg, 2496 hashlen, hash, sig ); 2497 #endif 2498 2499 default: 2500 return( MBEDTLS_ERR_RSA_INVALID_PADDING ); 2501 } 2502 } 2503 2504 /* 2505 * Copy the components of an RSA key 2506 */ 2507 int mbedtls_rsa_copy( mbedtls_rsa_context *dst, const mbedtls_rsa_context *src ) 2508 { 2509 int ret; 2510 RSA_VALIDATE_RET( dst != NULL ); 2511 RSA_VALIDATE_RET( src != NULL ); 2512 2513 dst->len = src->len; 2514 2515 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->N, &src->N ) ); 2516 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->E, &src->E ) ); 2517 2518 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->D, &src->D ) ); 2519 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->P, &src->P ) ); 2520 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Q, &src->Q ) ); 2521 2522 #if !defined(MBEDTLS_RSA_NO_CRT) 2523 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DP, &src->DP ) ); 2524 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DQ, &src->DQ ) ); 2525 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->QP, &src->QP ) ); 2526 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RP, &src->RP ) ); 2527 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RQ, &src->RQ ) ); 2528 #endif 2529 2530 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RN, &src->RN ) ); 2531 2532 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vi, &src->Vi ) ); 2533 MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vf, &src->Vf ) ); 2534 2535 dst->padding = src->padding; 2536 dst->hash_id = src->hash_id; 2537 2538 cleanup: 2539 if( ret != 0 ) 2540 mbedtls_rsa_free( dst ); 2541 2542 return( ret ); 2543 } 2544 2545 /* 2546 * Free the components of an RSA key 2547 */ 2548 void mbedtls_rsa_free( mbedtls_rsa_context *ctx ) 2549 { 2550 if( ctx == NULL ) 2551 return; 2552 2553 mbedtls_mpi_free( &ctx->Vi ); 2554 mbedtls_mpi_free( &ctx->Vf ); 2555 mbedtls_mpi_free( &ctx->RN ); 2556 mbedtls_mpi_free( &ctx->D ); 2557 mbedtls_mpi_free( &ctx->Q ); 2558 mbedtls_mpi_free( &ctx->P ); 2559 mbedtls_mpi_free( &ctx->E ); 2560 mbedtls_mpi_free( &ctx->N ); 2561 2562 #if !defined(MBEDTLS_RSA_NO_CRT) 2563 mbedtls_mpi_free( &ctx->RQ ); 2564 mbedtls_mpi_free( &ctx->RP ); 2565 mbedtls_mpi_free( &ctx->QP ); 2566 mbedtls_mpi_free( &ctx->DQ ); 2567 mbedtls_mpi_free( &ctx->DP ); 2568 #endif /* MBEDTLS_RSA_NO_CRT */ 2569 2570 #if defined(MBEDTLS_THREADING_C) 2571 /* Free the mutex, but only if it hasn't been freed already. */ 2572 if( ctx->ver != 0 ) 2573 { 2574 mbedtls_mutex_free( &ctx->mutex ); 2575 ctx->ver = 0; 2576 } 2577 #endif 2578 } 2579 2580 #endif /* !MBEDTLS_RSA_ALT */ 2581 2582 #if defined(MBEDTLS_SELF_TEST) 2583 2584 #include "mbedtls/sha1.h" 2585 2586 /* 2587 * Example RSA-1024 keypair, for test purposes 2588 */ 2589 #define KEY_LEN 128 2590 2591 #define RSA_N "9292758453063D803DD603D5E777D788" \ 2592 "8ED1D5BF35786190FA2F23EBC0848AEA" \ 2593 "DDA92CA6C3D80B32C4D109BE0F36D6AE" \ 2594 "7130B9CED7ACDF54CFC7555AC14EEBAB" \ 2595 "93A89813FBF3C4F8066D2D800F7C38A8" \ 2596 "1AE31942917403FF4946B0A83D3D3E05" \ 2597 "EE57C6F5F5606FB5D4BC6CD34EE0801A" \ 2598 "5E94BB77B07507233A0BC7BAC8F90F79" 2599 2600 #define RSA_E "10001" 2601 2602 #define RSA_D "24BF6185468786FDD303083D25E64EFC" \ 2603 "66CA472BC44D253102F8B4A9D3BFA750" \ 2604 "91386C0077937FE33FA3252D28855837" \ 2605 "AE1B484A8A9A45F7EE8C0C634F99E8CD" \ 2606 "DF79C5CE07EE72C7F123142198164234" \ 2607 "CABB724CF78B8173B9F880FC86322407" \ 2608 "AF1FEDFDDE2BEB674CA15F3E81A1521E" \ 2609 "071513A1E85B5DFA031F21ECAE91A34D" 2610 2611 #define RSA_P "C36D0EB7FCD285223CFB5AABA5BDA3D8" \ 2612 "2C01CAD19EA484A87EA4377637E75500" \ 2613 "FCB2005C5C7DD6EC4AC023CDA285D796" \ 2614 "C3D9E75E1EFC42488BB4F1D13AC30A57" 2615 2616 #define RSA_Q "C000DF51A7C77AE8D7C7370C1FF55B69" \ 2617 "E211C2B9E5DB1ED0BF61D0D9899620F4" \ 2618 "910E4168387E3C30AA1E00C339A79508" \ 2619 "8452DD96A9A5EA5D9DCA68DA636032AF" 2620 2621 #define PT_LEN 24 2622 #define RSA_PT "\xAA\xBB\xCC\x03\x02\x01\x00\xFF\xFF\xFF\xFF\xFF" \ 2623 "\x11\x22\x33\x0A\x0B\x0C\xCC\xDD\xDD\xDD\xDD\xDD" 2624 2625 #if defined(MBEDTLS_PKCS1_V15) 2626 static int myrand( void *rng_state, unsigned char *output, size_t len ) 2627 { 2628 #if !defined(__OpenBSD__) && !defined(__NetBSD__) 2629 size_t i; 2630 2631 if( rng_state != NULL ) 2632 rng_state = NULL; 2633 2634 for( i = 0; i < len; ++i ) 2635 output[i] = rand(); 2636 #else 2637 if( rng_state != NULL ) 2638 rng_state = NULL; 2639 2640 arc4random_buf( output, len ); 2641 #endif /* !OpenBSD && !NetBSD */ 2642 2643 return( 0 ); 2644 } 2645 #endif /* MBEDTLS_PKCS1_V15 */ 2646 2647 /* 2648 * Checkup routine 2649 */ 2650 int mbedtls_rsa_self_test( int verbose ) 2651 { 2652 int ret = 0; 2653 #if defined(MBEDTLS_PKCS1_V15) 2654 size_t len; 2655 mbedtls_rsa_context rsa; 2656 unsigned char rsa_plaintext[PT_LEN]; 2657 unsigned char rsa_decrypted[PT_LEN]; 2658 unsigned char rsa_ciphertext[KEY_LEN]; 2659 #if defined(MBEDTLS_SHA1_C) 2660 unsigned char sha1sum[20]; 2661 #endif 2662 2663 mbedtls_mpi K; 2664 2665 mbedtls_mpi_init( &K ); 2666 mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 ); 2667 2668 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_N ) ); 2669 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, &K, NULL, NULL, NULL, NULL ) ); 2670 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_P ) ); 2671 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, &K, NULL, NULL, NULL ) ); 2672 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_Q ) ); 2673 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, &K, NULL, NULL ) ); 2674 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_D ) ); 2675 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, NULL, &K, NULL ) ); 2676 MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_E ) ); 2677 MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, NULL, NULL, &K ) ); 2678 2679 MBEDTLS_MPI_CHK( mbedtls_rsa_complete( &rsa ) ); 2680 2681 if( verbose != 0 ) 2682 mbedtls_printf( " RSA key validation: " ); 2683 2684 if( mbedtls_rsa_check_pubkey( &rsa ) != 0 || 2685 mbedtls_rsa_check_privkey( &rsa ) != 0 ) 2686 { 2687 if( verbose != 0 ) 2688 mbedtls_printf( "failed\n" ); 2689 2690 ret = 1; 2691 goto cleanup; 2692 } 2693 2694 if( verbose != 0 ) 2695 mbedtls_printf( "passed\n PKCS#1 encryption : " ); 2696 2697 memcpy( rsa_plaintext, RSA_PT, PT_LEN ); 2698 2699 if( mbedtls_rsa_pkcs1_encrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PUBLIC, 2700 PT_LEN, rsa_plaintext, 2701 rsa_ciphertext ) != 0 ) 2702 { 2703 if( verbose != 0 ) 2704 mbedtls_printf( "failed\n" ); 2705 2706 ret = 1; 2707 goto cleanup; 2708 } 2709 2710 if( verbose != 0 ) 2711 mbedtls_printf( "passed\n PKCS#1 decryption : " ); 2712 2713 if( mbedtls_rsa_pkcs1_decrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PRIVATE, 2714 &len, rsa_ciphertext, rsa_decrypted, 2715 sizeof(rsa_decrypted) ) != 0 ) 2716 { 2717 if( verbose != 0 ) 2718 mbedtls_printf( "failed\n" ); 2719 2720 ret = 1; 2721 goto cleanup; 2722 } 2723 2724 if( memcmp( rsa_decrypted, rsa_plaintext, len ) != 0 ) 2725 { 2726 if( verbose != 0 ) 2727 mbedtls_printf( "failed\n" ); 2728 2729 ret = 1; 2730 goto cleanup; 2731 } 2732 2733 if( verbose != 0 ) 2734 mbedtls_printf( "passed\n" ); 2735 2736 #if defined(MBEDTLS_SHA1_C) 2737 if( verbose != 0 ) 2738 mbedtls_printf( " PKCS#1 data sign : " ); 2739 2740 if( mbedtls_sha1_ret( rsa_plaintext, PT_LEN, sha1sum ) != 0 ) 2741 { 2742 if( verbose != 0 ) 2743 mbedtls_printf( "failed\n" ); 2744 2745 return( 1 ); 2746 } 2747 2748 if( mbedtls_rsa_pkcs1_sign( &rsa, myrand, NULL, 2749 MBEDTLS_RSA_PRIVATE, MBEDTLS_MD_SHA1, 0, 2750 sha1sum, rsa_ciphertext ) != 0 ) 2751 { 2752 if( verbose != 0 ) 2753 mbedtls_printf( "failed\n" ); 2754 2755 ret = 1; 2756 goto cleanup; 2757 } 2758 2759 if( verbose != 0 ) 2760 mbedtls_printf( "passed\n PKCS#1 sig. verify: " ); 2761 2762 if( mbedtls_rsa_pkcs1_verify( &rsa, NULL, NULL, 2763 MBEDTLS_RSA_PUBLIC, MBEDTLS_MD_SHA1, 0, 2764 sha1sum, rsa_ciphertext ) != 0 ) 2765 { 2766 if( verbose != 0 ) 2767 mbedtls_printf( "failed\n" ); 2768 2769 ret = 1; 2770 goto cleanup; 2771 } 2772 2773 if( verbose != 0 ) 2774 mbedtls_printf( "passed\n" ); 2775 #endif /* MBEDTLS_SHA1_C */ 2776 2777 if( verbose != 0 ) 2778 mbedtls_printf( "\n" ); 2779 2780 cleanup: 2781 mbedtls_mpi_free( &K ); 2782 mbedtls_rsa_free( &rsa ); 2783 #else /* MBEDTLS_PKCS1_V15 */ 2784 ((void) verbose); 2785 #endif /* MBEDTLS_PKCS1_V15 */ 2786 return( ret ); 2787 } 2788 2789 #endif /* MBEDTLS_SELF_TEST */ 2790 2791 #endif /* MBEDTLS_RSA_C */ 2792