1 /* 2 * Public Key layer for writing key files and structures 3 * 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 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 * This file is part of mbed TLS (https://tls.mbed.org) 47 */ 48 49 #if !defined(MBEDTLS_CONFIG_FILE) 50 #include "mbedtls/config.h" 51 #else 52 #include MBEDTLS_CONFIG_FILE 53 #endif 54 55 #if defined(MBEDTLS_PK_WRITE_C) 56 57 #include "mbedtls/pk.h" 58 #include "mbedtls/asn1write.h" 59 #include "mbedtls/oid.h" 60 61 #include <string.h> 62 63 #if defined(MBEDTLS_RSA_C) 64 #include "mbedtls/rsa.h" 65 #endif 66 #if defined(MBEDTLS_ECP_C) 67 #include "mbedtls/bignum.h" 68 #include "mbedtls/ecp.h" 69 #endif 70 #if defined(MBEDTLS_ECDSA_C) 71 #include "mbedtls/ecdsa.h" 72 #endif 73 #if defined(MBEDTLS_PEM_WRITE_C) 74 #include "mbedtls/pem.h" 75 #endif 76 77 #if defined(MBEDTLS_PLATFORM_C) 78 #include "mbedtls/platform.h" 79 #else 80 #include <stdlib.h> 81 #define mbedtls_calloc calloc 82 #define mbedtls_free free 83 #endif 84 85 #if defined(MBEDTLS_ECP_C) 86 /* Implementation that should never be optimized out by the compiler */ 87 static void mbedtls_zeroize( void *v, size_t n ) { 88 volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0; 89 } 90 #endif /* MBEDTLS_ECP_C */ 91 92 #if defined(MBEDTLS_RSA_C) 93 /* 94 * RSAPublicKey ::= SEQUENCE { 95 * modulus INTEGER, -- n 96 * publicExponent INTEGER -- e 97 * } 98 */ 99 static int pk_write_rsa_pubkey( unsigned char **p, unsigned char *start, 100 mbedtls_rsa_context *rsa ) 101 { 102 int ret; 103 size_t len = 0; 104 mbedtls_mpi T; 105 106 mbedtls_mpi_init( &T ); 107 108 /* Export E */ 109 if ( ( ret = mbedtls_rsa_export( rsa, NULL, NULL, NULL, NULL, &T ) ) != 0 || 110 ( ret = mbedtls_asn1_write_mpi( p, start, &T ) ) < 0 ) 111 goto end_of_export; 112 len += ret; 113 114 /* Export N */ 115 if ( ( ret = mbedtls_rsa_export( rsa, &T, NULL, NULL, NULL, NULL ) ) != 0 || 116 ( ret = mbedtls_asn1_write_mpi( p, start, &T ) ) < 0 ) 117 goto end_of_export; 118 len += ret; 119 120 end_of_export: 121 122 mbedtls_mpi_free( &T ); 123 if( ret < 0 ) 124 return( ret ); 125 126 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); 127 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_CONSTRUCTED | 128 MBEDTLS_ASN1_SEQUENCE ) ); 129 130 return( (int) len ); 131 } 132 #endif /* MBEDTLS_RSA_C */ 133 134 #if defined(MBEDTLS_ECP_C) 135 /* 136 * EC public key is an EC point 137 */ 138 static int pk_write_ec_pubkey( unsigned char **p, unsigned char *start, 139 mbedtls_ecp_keypair *ec ) 140 { 141 int ret; 142 size_t len = 0; 143 unsigned char buf[MBEDTLS_ECP_MAX_PT_LEN]; 144 145 if( ( ret = mbedtls_ecp_point_write_binary( &ec->grp, &ec->Q, 146 MBEDTLS_ECP_PF_UNCOMPRESSED, 147 &len, buf, sizeof( buf ) ) ) != 0 ) 148 { 149 return( ret ); 150 } 151 152 if( *p < start || (size_t)( *p - start ) < len ) 153 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 154 155 *p -= len; 156 memcpy( *p, buf, len ); 157 158 return( (int) len ); 159 } 160 161 /* 162 * ECParameters ::= CHOICE { 163 * namedCurve OBJECT IDENTIFIER 164 * } 165 */ 166 static int pk_write_ec_param( unsigned char **p, unsigned char *start, 167 mbedtls_ecp_keypair *ec ) 168 { 169 int ret; 170 size_t len = 0; 171 const char *oid; 172 size_t oid_len; 173 174 if( ( ret = mbedtls_oid_get_oid_by_ec_grp( ec->grp.id, &oid, &oid_len ) ) != 0 ) 175 return( ret ); 176 177 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) ); 178 179 return( (int) len ); 180 } 181 182 /* 183 * privateKey OCTET STRING -- always of length ceil(log2(n)/8) 184 */ 185 static int pk_write_ec_private( unsigned char **p, unsigned char *start, 186 mbedtls_ecp_keypair *ec ) 187 { 188 int ret; 189 size_t byte_length = ( ec->grp.pbits + 7 ) / 8; 190 unsigned char tmp[MBEDTLS_ECP_MAX_BYTES]; 191 192 ret = mbedtls_mpi_write_binary( &ec->d, tmp, byte_length ); 193 if( ret != 0 ) 194 goto exit; 195 ret = mbedtls_asn1_write_octet_string( p, start, tmp, byte_length ); 196 197 exit: 198 mbedtls_zeroize( tmp, byte_length ); 199 return( ret ); 200 } 201 #endif /* MBEDTLS_ECP_C */ 202 203 int mbedtls_pk_write_pubkey( unsigned char **p, unsigned char *start, 204 const mbedtls_pk_context *key ) 205 { 206 int ret; 207 size_t len = 0; 208 209 #if defined(MBEDTLS_RSA_C) 210 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA ) 211 MBEDTLS_ASN1_CHK_ADD( len, pk_write_rsa_pubkey( p, start, mbedtls_pk_rsa( *key ) ) ); 212 else 213 #endif 214 #if defined(MBEDTLS_ECP_C) 215 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY ) 216 MBEDTLS_ASN1_CHK_ADD( len, pk_write_ec_pubkey( p, start, mbedtls_pk_ec( *key ) ) ); 217 else 218 #endif 219 return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE ); 220 221 return( (int) len ); 222 } 223 224 int mbedtls_pk_write_pubkey_der( mbedtls_pk_context *key, unsigned char *buf, size_t size ) 225 { 226 int ret; 227 unsigned char *c; 228 size_t len = 0, par_len = 0, oid_len; 229 const char *oid; 230 231 c = buf + size; 232 233 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_pk_write_pubkey( &c, buf, key ) ); 234 235 if( c - buf < 1 ) 236 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 237 238 /* 239 * SubjectPublicKeyInfo ::= SEQUENCE { 240 * algorithm AlgorithmIdentifier, 241 * subjectPublicKey BIT STRING } 242 */ 243 *--c = 0; 244 len += 1; 245 246 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); 247 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_BIT_STRING ) ); 248 249 if( ( ret = mbedtls_oid_get_oid_by_pk_alg( mbedtls_pk_get_type( key ), 250 &oid, &oid_len ) ) != 0 ) 251 { 252 return( ret ); 253 } 254 255 #if defined(MBEDTLS_ECP_C) 256 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY ) 257 { 258 MBEDTLS_ASN1_CHK_ADD( par_len, pk_write_ec_param( &c, buf, mbedtls_pk_ec( *key ) ) ); 259 } 260 #endif 261 262 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_algorithm_identifier( &c, buf, oid, oid_len, 263 par_len ) ); 264 265 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); 266 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | 267 MBEDTLS_ASN1_SEQUENCE ) ); 268 269 return( (int) len ); 270 } 271 272 int mbedtls_pk_write_key_der( mbedtls_pk_context *key, unsigned char *buf, size_t size ) 273 { 274 int ret; 275 unsigned char *c = buf + size; 276 size_t len = 0; 277 278 #if defined(MBEDTLS_RSA_C) 279 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA ) 280 { 281 mbedtls_mpi T; /* Temporary holding the exported parameters */ 282 mbedtls_rsa_context *rsa = mbedtls_pk_rsa( *key ); 283 284 /* 285 * Export the parameters one after another to avoid simultaneous copies. 286 */ 287 288 mbedtls_mpi_init( &T ); 289 290 /* Export QP */ 291 if( ( ret = mbedtls_rsa_export_crt( rsa, NULL, NULL, &T ) ) != 0 || 292 ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) 293 goto end_of_export; 294 len += ret; 295 296 /* Export DQ */ 297 if( ( ret = mbedtls_rsa_export_crt( rsa, NULL, &T, NULL ) ) != 0 || 298 ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) 299 goto end_of_export; 300 len += ret; 301 302 /* Export DP */ 303 if( ( ret = mbedtls_rsa_export_crt( rsa, &T, NULL, NULL ) ) != 0 || 304 ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) 305 goto end_of_export; 306 len += ret; 307 308 /* Export Q */ 309 if ( ( ret = mbedtls_rsa_export( rsa, NULL, NULL, 310 &T, NULL, NULL ) ) != 0 || 311 ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) 312 goto end_of_export; 313 len += ret; 314 315 /* Export P */ 316 if ( ( ret = mbedtls_rsa_export( rsa, NULL, &T, 317 NULL, NULL, NULL ) ) != 0 || 318 ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) 319 goto end_of_export; 320 len += ret; 321 322 /* Export D */ 323 if ( ( ret = mbedtls_rsa_export( rsa, NULL, NULL, 324 NULL, &T, NULL ) ) != 0 || 325 ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) 326 goto end_of_export; 327 len += ret; 328 329 /* Export E */ 330 if ( ( ret = mbedtls_rsa_export( rsa, NULL, NULL, 331 NULL, NULL, &T ) ) != 0 || 332 ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) 333 goto end_of_export; 334 len += ret; 335 336 /* Export N */ 337 if ( ( ret = mbedtls_rsa_export( rsa, &T, NULL, 338 NULL, NULL, NULL ) ) != 0 || 339 ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) 340 goto end_of_export; 341 len += ret; 342 343 end_of_export: 344 345 mbedtls_mpi_free( &T ); 346 if( ret < 0 ) 347 return( ret ); 348 349 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, buf, 0 ) ); 350 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); 351 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, 352 buf, MBEDTLS_ASN1_CONSTRUCTED | 353 MBEDTLS_ASN1_SEQUENCE ) ); 354 } 355 else 356 #endif /* MBEDTLS_RSA_C */ 357 #if defined(MBEDTLS_ECP_C) 358 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY ) 359 { 360 mbedtls_ecp_keypair *ec = mbedtls_pk_ec( *key ); 361 size_t pub_len = 0, par_len = 0; 362 363 /* 364 * RFC 5915, or SEC1 Appendix C.4 365 * 366 * ECPrivateKey ::= SEQUENCE { 367 * version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1), 368 * privateKey OCTET STRING, 369 * parameters [0] ECParameters {{ NamedCurve }} OPTIONAL, 370 * publicKey [1] BIT STRING OPTIONAL 371 * } 372 */ 373 374 /* publicKey */ 375 MBEDTLS_ASN1_CHK_ADD( pub_len, pk_write_ec_pubkey( &c, buf, ec ) ); 376 377 if( c - buf < 1 ) 378 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 379 *--c = 0; 380 pub_len += 1; 381 382 MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_len( &c, buf, pub_len ) ); 383 MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_BIT_STRING ) ); 384 385 MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_len( &c, buf, pub_len ) ); 386 MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_tag( &c, buf, 387 MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 1 ) ); 388 len += pub_len; 389 390 /* parameters */ 391 MBEDTLS_ASN1_CHK_ADD( par_len, pk_write_ec_param( &c, buf, ec ) ); 392 393 MBEDTLS_ASN1_CHK_ADD( par_len, mbedtls_asn1_write_len( &c, buf, par_len ) ); 394 MBEDTLS_ASN1_CHK_ADD( par_len, mbedtls_asn1_write_tag( &c, buf, 395 MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 0 ) ); 396 len += par_len; 397 398 /* privateKey */ 399 MBEDTLS_ASN1_CHK_ADD( len, pk_write_ec_private( &c, buf, ec ) ); 400 401 /* version */ 402 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, buf, 1 ) ); 403 404 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); 405 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | 406 MBEDTLS_ASN1_SEQUENCE ) ); 407 } 408 else 409 #endif /* MBEDTLS_ECP_C */ 410 return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE ); 411 412 return( (int) len ); 413 } 414 415 #if defined(MBEDTLS_PEM_WRITE_C) 416 417 #define PEM_BEGIN_PUBLIC_KEY "-----BEGIN PUBLIC KEY-----\n" 418 #define PEM_END_PUBLIC_KEY "-----END PUBLIC KEY-----\n" 419 420 #define PEM_BEGIN_PRIVATE_KEY_RSA "-----BEGIN RSA PRIVATE KEY-----\n" 421 #define PEM_END_PRIVATE_KEY_RSA "-----END RSA PRIVATE KEY-----\n" 422 #define PEM_BEGIN_PRIVATE_KEY_EC "-----BEGIN EC PRIVATE KEY-----\n" 423 #define PEM_END_PRIVATE_KEY_EC "-----END EC PRIVATE KEY-----\n" 424 425 /* 426 * Max sizes of key per types. Shown as tag + len (+ content). 427 */ 428 429 #if defined(MBEDTLS_RSA_C) 430 /* 431 * RSA public keys: 432 * SubjectPublicKeyInfo ::= SEQUENCE { 1 + 3 433 * algorithm AlgorithmIdentifier, 1 + 1 (sequence) 434 * + 1 + 1 + 9 (rsa oid) 435 * + 1 + 1 (params null) 436 * subjectPublicKey BIT STRING } 1 + 3 + (1 + below) 437 * RSAPublicKey ::= SEQUENCE { 1 + 3 438 * modulus INTEGER, -- n 1 + 3 + MPI_MAX + 1 439 * publicExponent INTEGER -- e 1 + 3 + MPI_MAX + 1 440 * } 441 */ 442 #define RSA_PUB_DER_MAX_BYTES 38 + 2 * MBEDTLS_MPI_MAX_SIZE 443 444 /* 445 * RSA private keys: 446 * RSAPrivateKey ::= SEQUENCE { 1 + 3 447 * version Version, 1 + 1 + 1 448 * modulus INTEGER, 1 + 3 + MPI_MAX + 1 449 * publicExponent INTEGER, 1 + 3 + MPI_MAX + 1 450 * privateExponent INTEGER, 1 + 3 + MPI_MAX + 1 451 * prime1 INTEGER, 1 + 3 + MPI_MAX / 2 + 1 452 * prime2 INTEGER, 1 + 3 + MPI_MAX / 2 + 1 453 * exponent1 INTEGER, 1 + 3 + MPI_MAX / 2 + 1 454 * exponent2 INTEGER, 1 + 3 + MPI_MAX / 2 + 1 455 * coefficient INTEGER, 1 + 3 + MPI_MAX / 2 + 1 456 * otherPrimeInfos OtherPrimeInfos OPTIONAL 0 (not supported) 457 * } 458 */ 459 #define MPI_MAX_SIZE_2 MBEDTLS_MPI_MAX_SIZE / 2 + \ 460 MBEDTLS_MPI_MAX_SIZE % 2 461 #define RSA_PRV_DER_MAX_BYTES 47 + 3 * MBEDTLS_MPI_MAX_SIZE \ 462 + 5 * MPI_MAX_SIZE_2 463 464 #else /* MBEDTLS_RSA_C */ 465 466 #define RSA_PUB_DER_MAX_BYTES 0 467 #define RSA_PRV_DER_MAX_BYTES 0 468 469 #endif /* MBEDTLS_RSA_C */ 470 471 #if defined(MBEDTLS_ECP_C) 472 /* 473 * EC public keys: 474 * SubjectPublicKeyInfo ::= SEQUENCE { 1 + 2 475 * algorithm AlgorithmIdentifier, 1 + 1 (sequence) 476 * + 1 + 1 + 7 (ec oid) 477 * + 1 + 1 + 9 (namedCurve oid) 478 * subjectPublicKey BIT STRING 1 + 2 + 1 [1] 479 * + 1 (point format) [1] 480 * + 2 * ECP_MAX (coords) [1] 481 * } 482 */ 483 #define ECP_PUB_DER_MAX_BYTES 30 + 2 * MBEDTLS_ECP_MAX_BYTES 484 485 /* 486 * EC private keys: 487 * ECPrivateKey ::= SEQUENCE { 1 + 2 488 * version INTEGER , 1 + 1 + 1 489 * privateKey OCTET STRING, 1 + 1 + ECP_MAX 490 * parameters [0] ECParameters OPTIONAL, 1 + 1 + (1 + 1 + 9) 491 * publicKey [1] BIT STRING OPTIONAL 1 + 2 + [1] above 492 * } 493 */ 494 #define ECP_PRV_DER_MAX_BYTES 29 + 3 * MBEDTLS_ECP_MAX_BYTES 495 496 #else /* MBEDTLS_ECP_C */ 497 498 #define ECP_PUB_DER_MAX_BYTES 0 499 #define ECP_PRV_DER_MAX_BYTES 0 500 501 #endif /* MBEDTLS_ECP_C */ 502 503 #define PUB_DER_MAX_BYTES RSA_PUB_DER_MAX_BYTES > ECP_PUB_DER_MAX_BYTES ? \ 504 RSA_PUB_DER_MAX_BYTES : ECP_PUB_DER_MAX_BYTES 505 #define PRV_DER_MAX_BYTES RSA_PRV_DER_MAX_BYTES > ECP_PRV_DER_MAX_BYTES ? \ 506 RSA_PRV_DER_MAX_BYTES : ECP_PRV_DER_MAX_BYTES 507 508 int mbedtls_pk_write_pubkey_pem( mbedtls_pk_context *key, unsigned char *buf, size_t size ) 509 { 510 int ret; 511 unsigned char output_buf[PUB_DER_MAX_BYTES]; 512 size_t olen = 0; 513 514 if( ( ret = mbedtls_pk_write_pubkey_der( key, output_buf, 515 sizeof(output_buf) ) ) < 0 ) 516 { 517 return( ret ); 518 } 519 520 if( ( ret = mbedtls_pem_write_buffer( PEM_BEGIN_PUBLIC_KEY, PEM_END_PUBLIC_KEY, 521 output_buf + sizeof(output_buf) - ret, 522 ret, buf, size, &olen ) ) != 0 ) 523 { 524 return( ret ); 525 } 526 527 return( 0 ); 528 } 529 530 int mbedtls_pk_write_key_pem( mbedtls_pk_context *key, unsigned char *buf, size_t size ) 531 { 532 int ret; 533 unsigned char output_buf[PRV_DER_MAX_BYTES]; 534 const char *begin, *end; 535 size_t olen = 0; 536 537 if( ( ret = mbedtls_pk_write_key_der( key, output_buf, sizeof(output_buf) ) ) < 0 ) 538 return( ret ); 539 540 #if defined(MBEDTLS_RSA_C) 541 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA ) 542 { 543 begin = PEM_BEGIN_PRIVATE_KEY_RSA; 544 end = PEM_END_PRIVATE_KEY_RSA; 545 } 546 else 547 #endif 548 #if defined(MBEDTLS_ECP_C) 549 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY ) 550 { 551 begin = PEM_BEGIN_PRIVATE_KEY_EC; 552 end = PEM_END_PRIVATE_KEY_EC; 553 } 554 else 555 #endif 556 return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE ); 557 558 if( ( ret = mbedtls_pem_write_buffer( begin, end, 559 output_buf + sizeof(output_buf) - ret, 560 ret, buf, size, &olen ) ) != 0 ) 561 { 562 return( ret ); 563 } 564 565 return( 0 ); 566 } 567 #endif /* MBEDTLS_PEM_WRITE_C */ 568 569 #endif /* MBEDTLS_PK_WRITE_C */ 570