1/* 2 * Privacy Enhanced Mail (PEM) decoding 3 * 4 * Copyright The Mbed TLS Contributors 5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 6 */ 7 8#include "common.h" 9 10#if defined(MBEDTLS_PEM_PARSE_C) || defined(MBEDTLS_PEM_WRITE_C) 11 12#include "mbedtls/pem.h" 13#include "mbedtls/base64.h" 14#include "mbedtls/des.h" 15#include "mbedtls/aes.h" 16#include "mbedtls/md.h" 17#include "mbedtls/cipher.h" 18#include "mbedtls/platform_util.h" 19#include "mbedtls/error.h" 20 21#include <string.h> 22 23#include "mbedtls/platform.h" 24 25#if defined(MBEDTLS_USE_PSA_CRYPTO) 26#include "psa/crypto.h" 27#endif 28 29#if defined(MBEDTLS_MD_CAN_MD5) && \ 30 defined(MBEDTLS_CIPHER_MODE_CBC) && \ 31 (defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C)) 32#define PEM_RFC1421 33#endif /* MBEDTLS_MD_CAN_MD5 && 34 MBEDTLS_CIPHER_MODE_CBC && 35 ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */ 36 37#if defined(MBEDTLS_PEM_PARSE_C) 38void mbedtls_pem_init(mbedtls_pem_context *ctx) 39{ 40 memset(ctx, 0, sizeof(mbedtls_pem_context)); 41} 42 43#if defined(PEM_RFC1421) 44/* 45 * Read a 16-byte hex string and convert it to binary 46 */ 47static int pem_get_iv(const unsigned char *s, unsigned char *iv, 48 size_t iv_len) 49{ 50 size_t i, j, k; 51 52 memset(iv, 0, iv_len); 53 54 for (i = 0; i < iv_len * 2; i++, s++) { 55 if (*s >= '0' && *s <= '9') { 56 j = *s - '0'; 57 } else 58 if (*s >= 'A' && *s <= 'F') { 59 j = *s - '7'; 60 } else 61 if (*s >= 'a' && *s <= 'f') { 62 j = *s - 'W'; 63 } else { 64 return MBEDTLS_ERR_PEM_INVALID_ENC_IV; 65 } 66 67 k = ((i & 1) != 0) ? j : j << 4; 68 69 iv[i >> 1] = (unsigned char) (iv[i >> 1] | k); 70 } 71 72 return 0; 73} 74 75static int pem_pbkdf1(unsigned char *key, size_t keylen, 76 unsigned char *iv, 77 const unsigned char *pwd, size_t pwdlen) 78{ 79 mbedtls_md_context_t md5_ctx; 80 const mbedtls_md_info_t *md5_info; 81 unsigned char md5sum[16]; 82 size_t use_len; 83 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 84 85 mbedtls_md_init(&md5_ctx); 86 87 /* Prepare the context. (setup() errors gracefully on NULL info.) */ 88 md5_info = mbedtls_md_info_from_type(MBEDTLS_MD_MD5); 89 if ((ret = mbedtls_md_setup(&md5_ctx, md5_info, 0)) != 0) { 90 goto exit; 91 } 92 93 /* 94 * key[ 0..15] = MD5(pwd || IV) 95 */ 96 if ((ret = mbedtls_md_starts(&md5_ctx)) != 0) { 97 goto exit; 98 } 99 if ((ret = mbedtls_md_update(&md5_ctx, pwd, pwdlen)) != 0) { 100 goto exit; 101 } 102 if ((ret = mbedtls_md_update(&md5_ctx, iv, 8)) != 0) { 103 goto exit; 104 } 105 if ((ret = mbedtls_md_finish(&md5_ctx, md5sum)) != 0) { 106 goto exit; 107 } 108 109 if (keylen <= 16) { 110 memcpy(key, md5sum, keylen); 111 goto exit; 112 } 113 114 memcpy(key, md5sum, 16); 115 116 /* 117 * key[16..23] = MD5(key[ 0..15] || pwd || IV]) 118 */ 119 if ((ret = mbedtls_md_starts(&md5_ctx)) != 0) { 120 goto exit; 121 } 122 if ((ret = mbedtls_md_update(&md5_ctx, md5sum, 16)) != 0) { 123 goto exit; 124 } 125 if ((ret = mbedtls_md_update(&md5_ctx, pwd, pwdlen)) != 0) { 126 goto exit; 127 } 128 if ((ret = mbedtls_md_update(&md5_ctx, iv, 8)) != 0) { 129 goto exit; 130 } 131 if ((ret = mbedtls_md_finish(&md5_ctx, md5sum)) != 0) { 132 goto exit; 133 } 134 135 use_len = 16; 136 if (keylen < 32) { 137 use_len = keylen - 16; 138 } 139 140 memcpy(key + 16, md5sum, use_len); 141 142exit: 143 mbedtls_md_free(&md5_ctx); 144 mbedtls_platform_zeroize(md5sum, 16); 145 146 return ret; 147} 148 149#if defined(MBEDTLS_DES_C) 150/* 151 * Decrypt with DES-CBC, using PBKDF1 for key derivation 152 */ 153static int pem_des_decrypt(unsigned char des_iv[8], 154 unsigned char *buf, size_t buflen, 155 const unsigned char *pwd, size_t pwdlen) 156{ 157 mbedtls_des_context des_ctx; 158 unsigned char des_key[8]; 159 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 160 161 mbedtls_des_init(&des_ctx); 162 163 if ((ret = pem_pbkdf1(des_key, 8, des_iv, pwd, pwdlen)) != 0) { 164 goto exit; 165 } 166 167 if ((ret = mbedtls_des_setkey_dec(&des_ctx, des_key)) != 0) { 168 goto exit; 169 } 170 ret = mbedtls_des_crypt_cbc(&des_ctx, MBEDTLS_DES_DECRYPT, buflen, 171 des_iv, buf, buf); 172 173exit: 174 mbedtls_des_free(&des_ctx); 175 mbedtls_platform_zeroize(des_key, 8); 176 177 return ret; 178} 179 180/* 181 * Decrypt with 3DES-CBC, using PBKDF1 for key derivation 182 */ 183static int pem_des3_decrypt(unsigned char des3_iv[8], 184 unsigned char *buf, size_t buflen, 185 const unsigned char *pwd, size_t pwdlen) 186{ 187 mbedtls_des3_context des3_ctx; 188 unsigned char des3_key[24]; 189 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 190 191 mbedtls_des3_init(&des3_ctx); 192 193 if ((ret = pem_pbkdf1(des3_key, 24, des3_iv, pwd, pwdlen)) != 0) { 194 goto exit; 195 } 196 197 if ((ret = mbedtls_des3_set3key_dec(&des3_ctx, des3_key)) != 0) { 198 goto exit; 199 } 200 ret = mbedtls_des3_crypt_cbc(&des3_ctx, MBEDTLS_DES_DECRYPT, buflen, 201 des3_iv, buf, buf); 202 203exit: 204 mbedtls_des3_free(&des3_ctx); 205 mbedtls_platform_zeroize(des3_key, 24); 206 207 return ret; 208} 209#endif /* MBEDTLS_DES_C */ 210 211#if defined(MBEDTLS_AES_C) 212/* 213 * Decrypt with AES-XXX-CBC, using PBKDF1 for key derivation 214 */ 215static int pem_aes_decrypt(unsigned char aes_iv[16], unsigned int keylen, 216 unsigned char *buf, size_t buflen, 217 const unsigned char *pwd, size_t pwdlen) 218{ 219 mbedtls_aes_context aes_ctx; 220 unsigned char aes_key[32]; 221 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 222 223 mbedtls_aes_init(&aes_ctx); 224 225 if ((ret = pem_pbkdf1(aes_key, keylen, aes_iv, pwd, pwdlen)) != 0) { 226 goto exit; 227 } 228 229 if ((ret = mbedtls_aes_setkey_dec(&aes_ctx, aes_key, keylen * 8)) != 0) { 230 goto exit; 231 } 232 ret = mbedtls_aes_crypt_cbc(&aes_ctx, MBEDTLS_AES_DECRYPT, buflen, 233 aes_iv, buf, buf); 234 235exit: 236 mbedtls_aes_free(&aes_ctx); 237 mbedtls_platform_zeroize(aes_key, keylen); 238 239 return ret; 240} 241#endif /* MBEDTLS_AES_C */ 242 243#if defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) 244static int pem_check_pkcs_padding(unsigned char *input, size_t input_len, size_t *data_len) 245{ 246 /* input_len > 0 is guaranteed by mbedtls_pem_read_buffer(). */ 247 size_t pad_len = input[input_len - 1]; 248 size_t i; 249 250 if (pad_len > input_len) { 251 return MBEDTLS_ERR_PEM_PASSWORD_MISMATCH; 252 } 253 254 *data_len = input_len - pad_len; 255 256 for (i = *data_len; i < input_len; i++) { 257 if (input[i] != pad_len) { 258 return MBEDTLS_ERR_PEM_PASSWORD_MISMATCH; 259 } 260 } 261 262 return 0; 263} 264#endif /* MBEDTLS_DES_C || MBEDTLS_AES_C */ 265 266#endif /* PEM_RFC1421 */ 267 268int mbedtls_pem_read_buffer(mbedtls_pem_context *ctx, const char *header, const char *footer, 269 const unsigned char *data, const unsigned char *pwd, 270 size_t pwdlen, size_t *use_len) 271{ 272 int ret, enc; 273 size_t len; 274 unsigned char *buf; 275 const unsigned char *s1, *s2, *end; 276#if defined(PEM_RFC1421) 277 unsigned char pem_iv[16]; 278 mbedtls_cipher_type_t enc_alg = MBEDTLS_CIPHER_NONE; 279#else 280 ((void) pwd); 281 ((void) pwdlen); 282#endif /* PEM_RFC1421 */ 283 284 if (ctx == NULL) { 285 return MBEDTLS_ERR_PEM_BAD_INPUT_DATA; 286 } 287 288 s1 = (unsigned char *) strstr((const char *) data, header); 289 290 if (s1 == NULL) { 291 return MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT; 292 } 293 294 s2 = (unsigned char *) strstr((const char *) data, footer); 295 296 if (s2 == NULL || s2 <= s1) { 297 return MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT; 298 } 299 300 s1 += strlen(header); 301 if (*s1 == ' ') { 302 s1++; 303 } 304 if (*s1 == '\r') { 305 s1++; 306 } 307 if (*s1 == '\n') { 308 s1++; 309 } else { 310 return MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT; 311 } 312 313 end = s2; 314 end += strlen(footer); 315 if (*end == ' ') { 316 end++; 317 } 318 if (*end == '\r') { 319 end++; 320 } 321 if (*end == '\n') { 322 end++; 323 } 324 *use_len = (size_t) (end - data); 325 326 enc = 0; 327 328 if (s2 - s1 >= 22 && memcmp(s1, "Proc-Type: 4,ENCRYPTED", 22) == 0) { 329#if defined(PEM_RFC1421) 330 enc++; 331 332 s1 += 22; 333 if (*s1 == '\r') { 334 s1++; 335 } 336 if (*s1 == '\n') { 337 s1++; 338 } else { 339 return MBEDTLS_ERR_PEM_INVALID_DATA; 340 } 341 342 343#if defined(MBEDTLS_DES_C) 344 if (s2 - s1 >= 23 && memcmp(s1, "DEK-Info: DES-EDE3-CBC,", 23) == 0) { 345 enc_alg = MBEDTLS_CIPHER_DES_EDE3_CBC; 346 347 s1 += 23; 348 if (s2 - s1 < 16 || pem_get_iv(s1, pem_iv, 8) != 0) { 349 return MBEDTLS_ERR_PEM_INVALID_ENC_IV; 350 } 351 352 s1 += 16; 353 } else if (s2 - s1 >= 18 && memcmp(s1, "DEK-Info: DES-CBC,", 18) == 0) { 354 enc_alg = MBEDTLS_CIPHER_DES_CBC; 355 356 s1 += 18; 357 if (s2 - s1 < 16 || pem_get_iv(s1, pem_iv, 8) != 0) { 358 return MBEDTLS_ERR_PEM_INVALID_ENC_IV; 359 } 360 361 s1 += 16; 362 } 363#endif /* MBEDTLS_DES_C */ 364 365#if defined(MBEDTLS_AES_C) 366 if (s2 - s1 >= 14 && memcmp(s1, "DEK-Info: AES-", 14) == 0) { 367 if (s2 - s1 < 22) { 368 return MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG; 369 } else if (memcmp(s1, "DEK-Info: AES-128-CBC,", 22) == 0) { 370 enc_alg = MBEDTLS_CIPHER_AES_128_CBC; 371 } else if (memcmp(s1, "DEK-Info: AES-192-CBC,", 22) == 0) { 372 enc_alg = MBEDTLS_CIPHER_AES_192_CBC; 373 } else if (memcmp(s1, "DEK-Info: AES-256-CBC,", 22) == 0) { 374 enc_alg = MBEDTLS_CIPHER_AES_256_CBC; 375 } else { 376 return MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG; 377 } 378 379 s1 += 22; 380 if (s2 - s1 < 32 || pem_get_iv(s1, pem_iv, 16) != 0) { 381 return MBEDTLS_ERR_PEM_INVALID_ENC_IV; 382 } 383 384 s1 += 32; 385 } 386#endif /* MBEDTLS_AES_C */ 387 388 if (enc_alg == MBEDTLS_CIPHER_NONE) { 389 return MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG; 390 } 391 392 if (*s1 == '\r') { 393 s1++; 394 } 395 if (*s1 == '\n') { 396 s1++; 397 } else { 398 return MBEDTLS_ERR_PEM_INVALID_DATA; 399 } 400#else 401 return MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE; 402#endif /* PEM_RFC1421 */ 403 } 404 405 if (s1 >= s2) { 406 return MBEDTLS_ERR_PEM_INVALID_DATA; 407 } 408 409 ret = mbedtls_base64_decode(NULL, 0, &len, s1, (size_t) (s2 - s1)); 410 411 if (ret == MBEDTLS_ERR_BASE64_INVALID_CHARACTER) { 412 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PEM_INVALID_DATA, ret); 413 } 414 415 if (len == 0) { 416 return MBEDTLS_ERR_PEM_BAD_INPUT_DATA; 417 } 418 419 if ((buf = mbedtls_calloc(1, len)) == NULL) { 420 return MBEDTLS_ERR_PEM_ALLOC_FAILED; 421 } 422 423 if ((ret = mbedtls_base64_decode(buf, len, &len, s1, (size_t) (s2 - s1))) != 0) { 424 mbedtls_zeroize_and_free(buf, len); 425 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PEM_INVALID_DATA, ret); 426 } 427 428 if (enc != 0) { 429#if defined(PEM_RFC1421) 430 if (pwd == NULL) { 431 mbedtls_zeroize_and_free(buf, len); 432 return MBEDTLS_ERR_PEM_PASSWORD_REQUIRED; 433 } 434 435 ret = 0; 436 437#if defined(MBEDTLS_DES_C) 438 if (enc_alg == MBEDTLS_CIPHER_DES_EDE3_CBC) { 439 ret = pem_des3_decrypt(pem_iv, buf, len, pwd, pwdlen); 440 } else if (enc_alg == MBEDTLS_CIPHER_DES_CBC) { 441 ret = pem_des_decrypt(pem_iv, buf, len, pwd, pwdlen); 442 } 443#endif /* MBEDTLS_DES_C */ 444 445#if defined(MBEDTLS_AES_C) 446 if (enc_alg == MBEDTLS_CIPHER_AES_128_CBC) { 447 ret = pem_aes_decrypt(pem_iv, 16, buf, len, pwd, pwdlen); 448 } else if (enc_alg == MBEDTLS_CIPHER_AES_192_CBC) { 449 ret = pem_aes_decrypt(pem_iv, 24, buf, len, pwd, pwdlen); 450 } else if (enc_alg == MBEDTLS_CIPHER_AES_256_CBC) { 451 ret = pem_aes_decrypt(pem_iv, 32, buf, len, pwd, pwdlen); 452 } 453#endif /* MBEDTLS_AES_C */ 454 455 if (ret != 0) { 456 mbedtls_zeroize_and_free(buf, len); 457 return ret; 458 } 459 460 /* Check PKCS padding and update data length based on padding info. 461 * This can be used to detect invalid padding data and password 462 * mismatches. */ 463 size_t unpadded_len; 464 ret = pem_check_pkcs_padding(buf, len, &unpadded_len); 465 if (ret != 0) { 466 mbedtls_zeroize_and_free(buf, len); 467 return ret; 468 } 469 len = unpadded_len; 470#else 471 mbedtls_zeroize_and_free(buf, len); 472 return MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE; 473#endif /* PEM_RFC1421 */ 474 } 475 476 ctx->buf = buf; 477 ctx->buflen = len; 478 479 return 0; 480} 481 482void mbedtls_pem_free(mbedtls_pem_context *ctx) 483{ 484 if (ctx->buf != NULL) { 485 mbedtls_zeroize_and_free(ctx->buf, ctx->buflen); 486 } 487 mbedtls_free(ctx->info); 488 489 mbedtls_platform_zeroize(ctx, sizeof(mbedtls_pem_context)); 490} 491#endif /* MBEDTLS_PEM_PARSE_C */ 492 493#if defined(MBEDTLS_PEM_WRITE_C) 494int mbedtls_pem_write_buffer(const char *header, const char *footer, 495 const unsigned char *der_data, size_t der_len, 496 unsigned char *buf, size_t buf_len, size_t *olen) 497{ 498 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 499 unsigned char *encode_buf = NULL, *c, *p = buf; 500 size_t len = 0, use_len, add_len = 0; 501 502 mbedtls_base64_encode(NULL, 0, &use_len, der_data, der_len); 503 add_len = strlen(header) + strlen(footer) + (((use_len > 2) ? (use_len - 2) : 0) / 64) + 1; 504 505 if (use_len + add_len > buf_len) { 506 *olen = use_len + add_len; 507 return MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL; 508 } 509 510 if (use_len != 0 && 511 ((encode_buf = mbedtls_calloc(1, use_len)) == NULL)) { 512 return MBEDTLS_ERR_PEM_ALLOC_FAILED; 513 } 514 515 if ((ret = mbedtls_base64_encode(encode_buf, use_len, &use_len, der_data, 516 der_len)) != 0) { 517 mbedtls_free(encode_buf); 518 return ret; 519 } 520 521 memcpy(p, header, strlen(header)); 522 p += strlen(header); 523 c = encode_buf; 524 525 while (use_len) { 526 len = (use_len > 64) ? 64 : use_len; 527 memcpy(p, c, len); 528 use_len -= len; 529 p += len; 530 c += len; 531 *p++ = '\n'; 532 } 533 534 memcpy(p, footer, strlen(footer)); 535 p += strlen(footer); 536 537 *p++ = '\0'; 538 *olen = (size_t) (p - buf); 539 540 /* Clean any remaining data previously written to the buffer */ 541 memset(buf + *olen, 0, buf_len - *olen); 542 543 mbedtls_free(encode_buf); 544 return 0; 545} 546#endif /* MBEDTLS_PEM_WRITE_C */ 547#endif /* MBEDTLS_PEM_PARSE_C || MBEDTLS_PEM_WRITE_C */ 548