pkwrite.c (20717B)
1 /* 2 * Public Key layer for writing key files and structures 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_PK_WRITE_C) 11 12 #include "mbedtls/pk.h" 13 #include "mbedtls/asn1write.h" 14 #include "mbedtls/oid.h" 15 #include "mbedtls/platform_util.h" 16 #include "mbedtls/error.h" 17 #include "pk_internal.h" 18 19 #include <string.h> 20 21 #if defined(MBEDTLS_ECP_C) 22 #include "mbedtls/bignum.h" 23 #include "mbedtls/ecp.h" 24 #include "mbedtls/platform_util.h" 25 #endif 26 #if defined(MBEDTLS_PK_HAVE_ECC_KEYS) 27 #include "pk_internal.h" 28 #endif 29 #if defined(MBEDTLS_RSA_C) || defined(MBEDTLS_PK_HAVE_ECC_KEYS) 30 #include "pkwrite.h" 31 #endif 32 #if defined(MBEDTLS_PEM_WRITE_C) 33 #include "mbedtls/pem.h" 34 #endif 35 #if defined(MBEDTLS_RSA_C) 36 #include "rsa_internal.h" 37 #endif 38 39 #if defined(MBEDTLS_USE_PSA_CRYPTO) 40 #include "psa/crypto.h" 41 #include "psa_util_internal.h" 42 #endif 43 #include "mbedtls/platform.h" 44 45 /* Helpers for properly sizing buffers aimed at holding public keys or 46 * key-pairs based on build symbols. */ 47 #if defined(MBEDTLS_PK_USE_PSA_EC_DATA) 48 #define PK_MAX_EC_PUBLIC_KEY_SIZE PSA_EXPORT_PUBLIC_KEY_MAX_SIZE 49 #define PK_MAX_EC_KEY_PAIR_SIZE MBEDTLS_PSA_MAX_EC_KEY_PAIR_LENGTH 50 #elif defined(MBEDTLS_USE_PSA_CRYPTO) 51 #define PK_MAX_EC_PUBLIC_KEY_SIZE PSA_EXPORT_PUBLIC_KEY_MAX_SIZE 52 #define PK_MAX_EC_KEY_PAIR_SIZE MBEDTLS_PSA_MAX_EC_KEY_PAIR_LENGTH 53 #else 54 #define PK_MAX_EC_PUBLIC_KEY_SIZE MBEDTLS_ECP_MAX_PT_LEN 55 #define PK_MAX_EC_KEY_PAIR_SIZE MBEDTLS_ECP_MAX_BYTES 56 #endif 57 58 /****************************************************************************** 59 * Internal functions for RSA keys. 60 ******************************************************************************/ 61 #if defined(MBEDTLS_RSA_C) 62 static int pk_write_rsa_der(unsigned char **p, unsigned char *buf, 63 const mbedtls_pk_context *pk) 64 { 65 #if defined(MBEDTLS_USE_PSA_CRYPTO) 66 if (mbedtls_pk_get_type(pk) == MBEDTLS_PK_OPAQUE) { 67 uint8_t tmp[PSA_EXPORT_KEY_PAIR_MAX_SIZE]; 68 size_t tmp_len = 0; 69 70 if (psa_export_key(pk->priv_id, tmp, sizeof(tmp), &tmp_len) != PSA_SUCCESS) { 71 return MBEDTLS_ERR_PK_BAD_INPUT_DATA; 72 } 73 /* Ensure there's enough space in the provided buffer before copying data into it. */ 74 if (tmp_len > (size_t) (*p - buf)) { 75 mbedtls_platform_zeroize(tmp, sizeof(tmp)); 76 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; 77 } 78 *p -= tmp_len; 79 memcpy(*p, tmp, tmp_len); 80 mbedtls_platform_zeroize(tmp, sizeof(tmp)); 81 82 return (int) tmp_len; 83 } 84 #endif /* MBEDTLS_USE_PSA_CRYPTO */ 85 return mbedtls_rsa_write_key(mbedtls_pk_rsa(*pk), buf, p); 86 } 87 #endif /* MBEDTLS_RSA_C */ 88 89 /****************************************************************************** 90 * Internal functions for EC keys. 91 ******************************************************************************/ 92 #if defined(MBEDTLS_PK_HAVE_ECC_KEYS) 93 #if defined(MBEDTLS_PK_USE_PSA_EC_DATA) 94 static int pk_write_ec_pubkey(unsigned char **p, unsigned char *start, 95 const mbedtls_pk_context *pk) 96 { 97 size_t len = 0; 98 uint8_t buf[PK_MAX_EC_PUBLIC_KEY_SIZE]; 99 100 if (mbedtls_pk_get_type(pk) == MBEDTLS_PK_OPAQUE) { 101 if (psa_export_public_key(pk->priv_id, buf, sizeof(buf), &len) != PSA_SUCCESS) { 102 return MBEDTLS_ERR_PK_BAD_INPUT_DATA; 103 } 104 } else { 105 len = pk->pub_raw_len; 106 memcpy(buf, pk->pub_raw, len); 107 } 108 109 if (*p < start || (size_t) (*p - start) < len) { 110 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; 111 } 112 113 *p -= len; 114 memcpy(*p, buf, len); 115 116 return (int) len; 117 } 118 #else /* MBEDTLS_PK_USE_PSA_EC_DATA */ 119 static int pk_write_ec_pubkey(unsigned char **p, unsigned char *start, 120 const mbedtls_pk_context *pk) 121 { 122 size_t len = 0; 123 unsigned char buf[PK_MAX_EC_PUBLIC_KEY_SIZE]; 124 mbedtls_ecp_keypair *ec = mbedtls_pk_ec(*pk); 125 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 126 127 #if defined(MBEDTLS_USE_PSA_CRYPTO) 128 if (mbedtls_pk_get_type(pk) == MBEDTLS_PK_OPAQUE) { 129 if (psa_export_public_key(pk->priv_id, buf, sizeof(buf), &len) != PSA_SUCCESS) { 130 return MBEDTLS_ERR_PK_BAD_INPUT_DATA; 131 } 132 /* Ensure there's enough space in the provided buffer before copying data into it. */ 133 if (len > (size_t) (*p - start)) { 134 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; 135 } 136 *p -= len; 137 memcpy(*p, buf, len); 138 return (int) len; 139 } else 140 #endif /* MBEDTLS_USE_PSA_CRYPTO */ 141 { 142 if ((ret = mbedtls_ecp_point_write_binary(&ec->grp, &ec->Q, 143 MBEDTLS_ECP_PF_UNCOMPRESSED, 144 &len, buf, sizeof(buf))) != 0) { 145 return ret; 146 } 147 } 148 149 if (*p < start || (size_t) (*p - start) < len) { 150 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; 151 } 152 153 *p -= len; 154 memcpy(*p, buf, len); 155 156 return (int) len; 157 } 158 #endif /* MBEDTLS_PK_USE_PSA_EC_DATA */ 159 160 /* 161 * privateKey OCTET STRING -- always of length ceil(log2(n)/8) 162 */ 163 #if defined(MBEDTLS_PK_USE_PSA_EC_DATA) 164 static int pk_write_ec_private(unsigned char **p, unsigned char *start, 165 const mbedtls_pk_context *pk) 166 { 167 size_t byte_length; 168 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 169 unsigned char tmp[PK_MAX_EC_KEY_PAIR_SIZE]; 170 psa_status_t status; 171 172 if (mbedtls_pk_get_type(pk) == MBEDTLS_PK_OPAQUE) { 173 status = psa_export_key(pk->priv_id, tmp, sizeof(tmp), &byte_length); 174 if (status != PSA_SUCCESS) { 175 ret = PSA_PK_ECDSA_TO_MBEDTLS_ERR(status); 176 return ret; 177 } 178 } else { 179 status = psa_export_key(pk->priv_id, tmp, sizeof(tmp), &byte_length); 180 if (status != PSA_SUCCESS) { 181 ret = PSA_PK_ECDSA_TO_MBEDTLS_ERR(status); 182 goto exit; 183 } 184 } 185 186 ret = mbedtls_asn1_write_octet_string(p, start, tmp, byte_length); 187 exit: 188 mbedtls_platform_zeroize(tmp, sizeof(tmp)); 189 return ret; 190 } 191 #else /* MBEDTLS_PK_USE_PSA_EC_DATA */ 192 static int pk_write_ec_private(unsigned char **p, unsigned char *start, 193 const mbedtls_pk_context *pk) 194 { 195 size_t byte_length; 196 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 197 unsigned char tmp[PK_MAX_EC_KEY_PAIR_SIZE]; 198 199 #if defined(MBEDTLS_USE_PSA_CRYPTO) 200 psa_status_t status; 201 if (mbedtls_pk_get_type(pk) == MBEDTLS_PK_OPAQUE) { 202 status = psa_export_key(pk->priv_id, tmp, sizeof(tmp), &byte_length); 203 if (status != PSA_SUCCESS) { 204 ret = PSA_PK_ECDSA_TO_MBEDTLS_ERR(status); 205 return ret; 206 } 207 } else 208 #endif /* MBEDTLS_USE_PSA_CRYPTO */ 209 { 210 mbedtls_ecp_keypair *ec = mbedtls_pk_ec_rw(*pk); 211 byte_length = (ec->grp.pbits + 7) / 8; 212 213 ret = mbedtls_ecp_write_key_ext(ec, &byte_length, tmp, sizeof(tmp)); 214 if (ret != 0) { 215 goto exit; 216 } 217 } 218 ret = mbedtls_asn1_write_octet_string(p, start, tmp, byte_length); 219 exit: 220 mbedtls_platform_zeroize(tmp, sizeof(tmp)); 221 return ret; 222 } 223 #endif /* MBEDTLS_PK_USE_PSA_EC_DATA */ 224 225 /* 226 * ECParameters ::= CHOICE { 227 * namedCurve OBJECT IDENTIFIER 228 * } 229 */ 230 static int pk_write_ec_param(unsigned char **p, unsigned char *start, 231 mbedtls_ecp_group_id grp_id) 232 { 233 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 234 size_t len = 0; 235 const char *oid; 236 size_t oid_len; 237 238 if ((ret = mbedtls_oid_get_oid_by_ec_grp(grp_id, &oid, &oid_len)) != 0) { 239 return ret; 240 } 241 242 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_oid(p, start, oid, oid_len)); 243 244 return (int) len; 245 } 246 247 #if defined(MBEDTLS_PK_HAVE_RFC8410_CURVES) 248 /* 249 * RFC8410 section 7 250 * 251 * OneAsymmetricKey ::= SEQUENCE { 252 * version Version, 253 * privateKeyAlgorithm PrivateKeyAlgorithmIdentifier, 254 * privateKey PrivateKey, 255 * attributes [0] IMPLICIT Attributes OPTIONAL, 256 * ..., 257 * [[2: publicKey [1] IMPLICIT PublicKey OPTIONAL ]], 258 * ... 259 * } 260 * ... 261 * CurvePrivateKey ::= OCTET STRING 262 */ 263 static int pk_write_ec_rfc8410_der(unsigned char **p, unsigned char *buf, 264 const mbedtls_pk_context *pk) 265 { 266 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 267 size_t len = 0; 268 size_t oid_len = 0; 269 const char *oid; 270 mbedtls_ecp_group_id grp_id; 271 272 /* privateKey */ 273 MBEDTLS_ASN1_CHK_ADD(len, pk_write_ec_private(p, buf, pk)); 274 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, buf, len)); 275 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, buf, MBEDTLS_ASN1_OCTET_STRING)); 276 277 grp_id = mbedtls_pk_get_ec_group_id(pk); 278 /* privateKeyAlgorithm */ 279 if ((ret = mbedtls_oid_get_oid_by_ec_grp_algid(grp_id, &oid, &oid_len)) != 0) { 280 return ret; 281 } 282 MBEDTLS_ASN1_CHK_ADD(len, 283 mbedtls_asn1_write_algorithm_identifier_ext(p, buf, oid, oid_len, 0, 0)); 284 285 /* version */ 286 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(p, buf, 0)); 287 288 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, buf, len)); 289 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, buf, MBEDTLS_ASN1_CONSTRUCTED | 290 MBEDTLS_ASN1_SEQUENCE)); 291 292 return (int) len; 293 } 294 #endif /* MBEDTLS_PK_HAVE_RFC8410_CURVES */ 295 296 /* 297 * RFC 5915, or SEC1 Appendix C.4 298 * 299 * ECPrivateKey ::= SEQUENCE { 300 * version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1), 301 * privateKey OCTET STRING, 302 * parameters [0] ECParameters {{ NamedCurve }} OPTIONAL, 303 * publicKey [1] BIT STRING OPTIONAL 304 * } 305 */ 306 static int pk_write_ec_der(unsigned char **p, unsigned char *buf, 307 const mbedtls_pk_context *pk) 308 { 309 size_t len = 0; 310 int ret; 311 size_t pub_len = 0, par_len = 0; 312 mbedtls_ecp_group_id grp_id; 313 314 /* publicKey */ 315 MBEDTLS_ASN1_CHK_ADD(pub_len, pk_write_ec_pubkey(p, buf, pk)); 316 317 if (*p - buf < 1) { 318 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; 319 } 320 (*p)--; 321 **p = 0; 322 pub_len += 1; 323 324 MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_len(p, buf, pub_len)); 325 MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_tag(p, buf, MBEDTLS_ASN1_BIT_STRING)); 326 327 MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_len(p, buf, pub_len)); 328 MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_tag(p, buf, 329 MBEDTLS_ASN1_CONTEXT_SPECIFIC | 330 MBEDTLS_ASN1_CONSTRUCTED | 1)); 331 len += pub_len; 332 333 /* parameters */ 334 grp_id = mbedtls_pk_get_ec_group_id(pk); 335 MBEDTLS_ASN1_CHK_ADD(par_len, pk_write_ec_param(p, buf, grp_id)); 336 MBEDTLS_ASN1_CHK_ADD(par_len, mbedtls_asn1_write_len(p, buf, par_len)); 337 MBEDTLS_ASN1_CHK_ADD(par_len, mbedtls_asn1_write_tag(p, buf, 338 MBEDTLS_ASN1_CONTEXT_SPECIFIC | 339 MBEDTLS_ASN1_CONSTRUCTED | 0)); 340 len += par_len; 341 342 /* privateKey */ 343 MBEDTLS_ASN1_CHK_ADD(len, pk_write_ec_private(p, buf, pk)); 344 345 /* version */ 346 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(p, buf, 1)); 347 348 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, buf, len)); 349 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, buf, MBEDTLS_ASN1_CONSTRUCTED | 350 MBEDTLS_ASN1_SEQUENCE)); 351 352 return (int) len; 353 } 354 #endif /* MBEDTLS_PK_HAVE_ECC_KEYS */ 355 356 /****************************************************************************** 357 * Internal functions for Opaque keys. 358 ******************************************************************************/ 359 #if defined(MBEDTLS_USE_PSA_CRYPTO) 360 static int pk_write_opaque_pubkey(unsigned char **p, unsigned char *start, 361 const mbedtls_pk_context *pk) 362 { 363 size_t buffer_size; 364 size_t len = 0; 365 366 if (*p < start) { 367 return MBEDTLS_ERR_PK_BAD_INPUT_DATA; 368 } 369 370 buffer_size = (size_t) (*p - start); 371 if (psa_export_public_key(pk->priv_id, start, buffer_size, 372 &len) != PSA_SUCCESS) { 373 return MBEDTLS_ERR_PK_BAD_INPUT_DATA; 374 } 375 376 *p -= len; 377 memmove(*p, start, len); 378 379 return (int) len; 380 } 381 #endif /* MBEDTLS_USE_PSA_CRYPTO */ 382 383 /****************************************************************************** 384 * Generic helpers 385 ******************************************************************************/ 386 387 /* Extend the public mbedtls_pk_get_type() by getting key type also in case of 388 * opaque keys. */ 389 static mbedtls_pk_type_t pk_get_type_ext(const mbedtls_pk_context *pk) 390 { 391 mbedtls_pk_type_t pk_type = mbedtls_pk_get_type(pk); 392 393 #if defined(MBEDTLS_USE_PSA_CRYPTO) 394 if (pk_type == MBEDTLS_PK_OPAQUE) { 395 psa_key_attributes_t opaque_attrs = PSA_KEY_ATTRIBUTES_INIT; 396 psa_key_type_t opaque_key_type; 397 398 if (psa_get_key_attributes(pk->priv_id, &opaque_attrs) != PSA_SUCCESS) { 399 return MBEDTLS_PK_NONE; 400 } 401 opaque_key_type = psa_get_key_type(&opaque_attrs); 402 psa_reset_key_attributes(&opaque_attrs); 403 404 if (PSA_KEY_TYPE_IS_ECC(opaque_key_type)) { 405 return MBEDTLS_PK_ECKEY; 406 } else if (PSA_KEY_TYPE_IS_RSA(opaque_key_type)) { 407 return MBEDTLS_PK_RSA; 408 } else { 409 return MBEDTLS_PK_NONE; 410 } 411 } else 412 #endif 413 return pk_type; 414 } 415 416 /****************************************************************************** 417 * Public functions for writing private/public DER keys. 418 ******************************************************************************/ 419 int mbedtls_pk_write_pubkey(unsigned char **p, unsigned char *start, 420 const mbedtls_pk_context *key) 421 { 422 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 423 size_t len = 0; 424 425 #if defined(MBEDTLS_RSA_C) 426 if (mbedtls_pk_get_type(key) == MBEDTLS_PK_RSA) { 427 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_rsa_write_pubkey(mbedtls_pk_rsa(*key), start, p)); 428 } else 429 #endif 430 #if defined(MBEDTLS_PK_HAVE_ECC_KEYS) 431 if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) { 432 MBEDTLS_ASN1_CHK_ADD(len, pk_write_ec_pubkey(p, start, key)); 433 } else 434 #endif 435 #if defined(MBEDTLS_USE_PSA_CRYPTO) 436 if (mbedtls_pk_get_type(key) == MBEDTLS_PK_OPAQUE) { 437 MBEDTLS_ASN1_CHK_ADD(len, pk_write_opaque_pubkey(p, start, key)); 438 } else 439 #endif /* MBEDTLS_USE_PSA_CRYPTO */ 440 return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE; 441 442 return (int) len; 443 } 444 445 int mbedtls_pk_write_pubkey_der(const mbedtls_pk_context *key, unsigned char *buf, size_t size) 446 { 447 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 448 unsigned char *c; 449 int has_par = 1; 450 size_t len = 0, par_len = 0, oid_len = 0; 451 mbedtls_pk_type_t pk_type; 452 const char *oid = NULL; 453 454 if (size == 0) { 455 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; 456 } 457 458 c = buf + size; 459 460 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_pk_write_pubkey(&c, buf, key)); 461 462 if (c - buf < 1) { 463 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; 464 } 465 466 /* 467 * SubjectPublicKeyInfo ::= SEQUENCE { 468 * algorithm AlgorithmIdentifier, 469 * subjectPublicKey BIT STRING } 470 */ 471 *--c = 0; 472 len += 1; 473 474 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len)); 475 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_BIT_STRING)); 476 477 pk_type = pk_get_type_ext(key); 478 479 #if defined(MBEDTLS_PK_HAVE_ECC_KEYS) 480 if (pk_get_type_ext(key) == MBEDTLS_PK_ECKEY) { 481 mbedtls_ecp_group_id ec_grp_id = mbedtls_pk_get_ec_group_id(key); 482 if (MBEDTLS_PK_IS_RFC8410_GROUP_ID(ec_grp_id)) { 483 ret = mbedtls_oid_get_oid_by_ec_grp_algid(ec_grp_id, &oid, &oid_len); 484 if (ret != 0) { 485 return ret; 486 } 487 has_par = 0; 488 } else { 489 MBEDTLS_ASN1_CHK_ADD(par_len, pk_write_ec_param(&c, buf, ec_grp_id)); 490 } 491 } 492 #endif /* MBEDTLS_PK_HAVE_ECC_KEYS */ 493 494 /* At this point oid_len is not null only for EC Montgomery keys. */ 495 if (oid_len == 0) { 496 ret = mbedtls_oid_get_oid_by_pk_alg(pk_type, &oid, &oid_len); 497 if (ret != 0) { 498 return ret; 499 } 500 } 501 502 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_algorithm_identifier_ext(&c, buf, oid, oid_len, 503 par_len, has_par)); 504 505 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len)); 506 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONSTRUCTED | 507 MBEDTLS_ASN1_SEQUENCE)); 508 509 return (int) len; 510 } 511 512 int mbedtls_pk_write_key_der(const mbedtls_pk_context *key, unsigned char *buf, size_t size) 513 { 514 unsigned char *c; 515 516 if (size == 0) { 517 return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL; 518 } 519 520 c = buf + size; 521 522 #if defined(MBEDTLS_RSA_C) 523 if (pk_get_type_ext(key) == MBEDTLS_PK_RSA) { 524 return pk_write_rsa_der(&c, buf, key); 525 } else 526 #endif /* MBEDTLS_RSA_C */ 527 #if defined(MBEDTLS_PK_HAVE_ECC_KEYS) 528 if (pk_get_type_ext(key) == MBEDTLS_PK_ECKEY) { 529 #if defined(MBEDTLS_PK_HAVE_RFC8410_CURVES) 530 if (mbedtls_pk_is_rfc8410(key)) { 531 return pk_write_ec_rfc8410_der(&c, buf, key); 532 } 533 #endif /* MBEDTLS_PK_HAVE_RFC8410_CURVES */ 534 return pk_write_ec_der(&c, buf, key); 535 } else 536 #endif /* MBEDTLS_PK_HAVE_ECC_KEYS */ 537 return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE; 538 } 539 540 /****************************************************************************** 541 * Public functions for wrinting private/public PEM keys. 542 ******************************************************************************/ 543 #if defined(MBEDTLS_PEM_WRITE_C) 544 545 #define PUB_DER_MAX_BYTES \ 546 (MBEDTLS_PK_RSA_PUB_DER_MAX_BYTES > MBEDTLS_PK_ECP_PUB_DER_MAX_BYTES ? \ 547 MBEDTLS_PK_RSA_PUB_DER_MAX_BYTES : MBEDTLS_PK_ECP_PUB_DER_MAX_BYTES) 548 #define PRV_DER_MAX_BYTES \ 549 (MBEDTLS_PK_RSA_PRV_DER_MAX_BYTES > MBEDTLS_PK_ECP_PRV_DER_MAX_BYTES ? \ 550 MBEDTLS_PK_RSA_PRV_DER_MAX_BYTES : MBEDTLS_PK_ECP_PRV_DER_MAX_BYTES) 551 552 int mbedtls_pk_write_pubkey_pem(const mbedtls_pk_context *key, unsigned char *buf, size_t size) 553 { 554 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 555 unsigned char *output_buf = NULL; 556 output_buf = mbedtls_calloc(1, PUB_DER_MAX_BYTES); 557 if (output_buf == NULL) { 558 return MBEDTLS_ERR_PK_ALLOC_FAILED; 559 } 560 size_t olen = 0; 561 562 if ((ret = mbedtls_pk_write_pubkey_der(key, output_buf, 563 PUB_DER_MAX_BYTES)) < 0) { 564 goto cleanup; 565 } 566 567 if ((ret = mbedtls_pem_write_buffer(PEM_BEGIN_PUBLIC_KEY "\n", PEM_END_PUBLIC_KEY "\n", 568 output_buf + PUB_DER_MAX_BYTES - ret, 569 ret, buf, size, &olen)) != 0) { 570 goto cleanup; 571 } 572 573 ret = 0; 574 cleanup: 575 mbedtls_free(output_buf); 576 return ret; 577 } 578 579 int mbedtls_pk_write_key_pem(const mbedtls_pk_context *key, unsigned char *buf, size_t size) 580 { 581 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 582 unsigned char *output_buf = NULL; 583 output_buf = mbedtls_calloc(1, PRV_DER_MAX_BYTES); 584 if (output_buf == NULL) { 585 return MBEDTLS_ERR_PK_ALLOC_FAILED; 586 } 587 const char *begin, *end; 588 size_t olen = 0; 589 590 if ((ret = mbedtls_pk_write_key_der(key, output_buf, PRV_DER_MAX_BYTES)) < 0) { 591 goto cleanup; 592 } 593 594 #if defined(MBEDTLS_RSA_C) 595 if (pk_get_type_ext(key) == MBEDTLS_PK_RSA) { 596 begin = PEM_BEGIN_PRIVATE_KEY_RSA "\n"; 597 end = PEM_END_PRIVATE_KEY_RSA "\n"; 598 } else 599 #endif 600 #if defined(MBEDTLS_PK_HAVE_ECC_KEYS) 601 if (pk_get_type_ext(key) == MBEDTLS_PK_ECKEY) { 602 if (mbedtls_pk_is_rfc8410(key)) { 603 begin = PEM_BEGIN_PRIVATE_KEY_PKCS8 "\n"; 604 end = PEM_END_PRIVATE_KEY_PKCS8 "\n"; 605 } else { 606 begin = PEM_BEGIN_PRIVATE_KEY_EC "\n"; 607 end = PEM_END_PRIVATE_KEY_EC "\n"; 608 } 609 } else 610 #endif /* MBEDTLS_PK_HAVE_ECC_KEYS */ 611 { 612 ret = MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE; 613 goto cleanup; 614 } 615 616 if ((ret = mbedtls_pem_write_buffer(begin, end, 617 output_buf + PRV_DER_MAX_BYTES - ret, 618 ret, buf, size, &olen)) != 0) { 619 goto cleanup; 620 } 621 622 ret = 0; 623 cleanup: 624 mbedtls_zeroize_and_free(output_buf, PRV_DER_MAX_BYTES); 625 return ret; 626 } 627 #endif /* MBEDTLS_PEM_WRITE_C */ 628 629 #endif /* MBEDTLS_PK_WRITE_C */