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   1 /**
   2  * \file pk.h
   3  *
   4  * \brief Public Key abstraction layer
   5  */
   6 /*
   7  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
   8  *  SPDX-License-Identifier: GPL-2.0
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License as published by
  12  *  the Free Software Foundation; either version 2 of the License, or
  13  *  (at your option) any later version.
  14  *
  15  *  This program is distributed in the hope that it will be useful,
  16  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  *  GNU General Public License for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License along
  21  *  with this program; if not, write to the Free Software Foundation, Inc.,
  22  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  *
  24  *  This file is part of mbed TLS (https://tls.mbed.org)
  25  */
  26
  27 #ifndef MBEDTLS_PK_H
  28 #define MBEDTLS_PK_H
  29
  30 #if !defined(MBEDTLS_CONFIG_FILE)
  31 #include "config.h"
  32 #else
  33 #include MBEDTLS_CONFIG_FILE
  34 #endif
  35
  36 #include "md.h"
  37
  38 #if defined(MBEDTLS_RSA_C)
  39 #include "rsa.h"
  40 #endif
  41
  42 #if defined(MBEDTLS_ECP_C)
  43 #include "ecp.h"
  44 #endif
  45
  46 #if defined(MBEDTLS_ECDSA_C)
  47 #include "ecdsa.h"
  48 #endif
  49
  50 #if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
  51     !defined(inline) && !defined(__cplusplus)
  52 #define inline __inline
  53 #endif
  54
  55 #define MBEDTLS_ERR_PK_ALLOC_FAILED        -0x3F80  /**< Memory allocation failed. */
  56 #define MBEDTLS_ERR_PK_TYPE_MISMATCH       -0x3F00  /**< Type mismatch, eg attempt to encrypt with an ECDSA key */
  57 #define MBEDTLS_ERR_PK_BAD_INPUT_DATA      -0x3E80  /**< Bad input parameters to function. */
  58 #define MBEDTLS_ERR_PK_FILE_IO_ERROR       -0x3E00  /**< Read/write of file failed. */
  59 #define MBEDTLS_ERR_PK_KEY_INVALID_VERSION -0x3D80  /**< Unsupported key version */
  60 #define MBEDTLS_ERR_PK_KEY_INVALID_FORMAT  -0x3D00  /**< Invalid key tag or value. */
  61 #define MBEDTLS_ERR_PK_UNKNOWN_PK_ALG      -0x3C80  /**< Key algorithm is unsupported (only RSA and EC are supported). */
  62 #define MBEDTLS_ERR_PK_PASSWORD_REQUIRED   -0x3C00  /**< Private key password can't be empty. */
  63 #define MBEDTLS_ERR_PK_PASSWORD_MISMATCH   -0x3B80  /**< Given private key password does not allow for correct decryption. */
  64 #define MBEDTLS_ERR_PK_INVALID_PUBKEY      -0x3B00  /**< The pubkey tag or value is invalid (only RSA and EC are supported). */
  65 #define MBEDTLS_ERR_PK_INVALID_ALG         -0x3A80  /**< The algorithm tag or value is invalid. */
  66 #define MBEDTLS_ERR_PK_UNKNOWN_NAMED_CURVE -0x3A00  /**< Elliptic curve is unsupported (only NIST curves are supported). */
  67 #define MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE -0x3980  /**< Unavailable feature, e.g. RSA disabled for RSA key. */
  68 #define MBEDTLS_ERR_PK_SIG_LEN_MISMATCH    -0x3900  /**< The buffer contains a valid signature followed by more data. */
  69 #define MBEDTLS_ERR_PK_HW_ACCEL_FAILED     -0x3880  /**< PK hardware accelerator failed. */
  70
  71 #ifdef __cplusplus
  72 extern "C" {
  73 #endif
  74
  75 /**
  76  * \brief          Public key types
  77  */
  78 typedef enum {
  79     MBEDTLS_PK_NONE=0,
  80     MBEDTLS_PK_RSA,
  81     MBEDTLS_PK_ECKEY,
  82     MBEDTLS_PK_ECKEY_DH,
  83     MBEDTLS_PK_ECDSA,
  84     MBEDTLS_PK_RSA_ALT,
  85     MBEDTLS_PK_RSASSA_PSS,
  86 } mbedtls_pk_type_t;
  87
  88 /**
  89  * \brief           Options for RSASSA-PSS signature verification.
  90  *                  See \c mbedtls_rsa_rsassa_pss_verify_ext()
  91  */
  92 typedef struct mbedtls_pk_rsassa_pss_options
  93 {
  94     mbedtls_md_type_t mgf1_hash_id;
  95     int expected_salt_len;
  96
  97 } mbedtls_pk_rsassa_pss_options;
  98
  99 /**
 100  * \brief           Types for interfacing with the debug module
 101  */
 102 typedef enum
 103 {
 104     MBEDTLS_PK_DEBUG_NONE = 0,
 105     MBEDTLS_PK_DEBUG_MPI,
 106     MBEDTLS_PK_DEBUG_ECP,
 107 } mbedtls_pk_debug_type;
 108
 109 /**
 110  * \brief           Item to send to the debug module
 111  */
 112 typedef struct mbedtls_pk_debug_item
 113 {
 114     mbedtls_pk_debug_type type;
 115     const char *name;
 116     void *value;
 117 } mbedtls_pk_debug_item;
 118
 119 /** Maximum number of item send for debugging, plus 1 */
 120 #define MBEDTLS_PK_DEBUG_MAX_ITEMS 3
 121
 122 /**
 123  * \brief           Public key information and operations
 124  */
 125 typedef struct mbedtls_pk_info_t mbedtls_pk_info_t;
 126
 127 /**
 128  * \brief           Public key container
 129  */
 130 typedef struct mbedtls_pk_context
 131 {
 132     const mbedtls_pk_info_t *   pk_info; /**< Public key informations        */
 133     void *                      pk_ctx;  /**< Underlying public key context  */
 134 } mbedtls_pk_context;
 135
 136 #if defined(MBEDTLS_RSA_C)
 137 /**
 138  * Quick access to an RSA context inside a PK context.
 139  *
 140  * \warning You must make sure the PK context actually holds an RSA context
 141  * before using this function!
 142  */
 143 static inline mbedtls_rsa_context *mbedtls_pk_rsa( const mbedtls_pk_context pk )
 144 {
 145     return( (mbedtls_rsa_context *) (pk).pk_ctx );
 146 }
 147 #endif /* MBEDTLS_RSA_C */
 148
 149 #if defined(MBEDTLS_ECP_C)
 150 /**
 151  * Quick access to an EC context inside a PK context.
 152  *
 153  * \warning You must make sure the PK context actually holds an EC context
 154  * before using this function!
 155  */
 156 static inline mbedtls_ecp_keypair *mbedtls_pk_ec( const mbedtls_pk_context pk )
 157 {
 158     return( (mbedtls_ecp_keypair *) (pk).pk_ctx );
 159 }
 160 #endif /* MBEDTLS_ECP_C */
 161
 162 #if defined(MBEDTLS_PK_RSA_ALT_SUPPORT)
 163 /**
 164  * \brief           Types for RSA-alt abstraction
 165  */
 166 typedef int (*mbedtls_pk_rsa_alt_decrypt_func)( void *ctx, int mode, size_t *olen,
 167                     const unsigned char *input, unsigned char *output,
 168                     size_t output_max_len );
 169 typedef int (*mbedtls_pk_rsa_alt_sign_func)( void *ctx,
 170                     int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
 171                     int mode, mbedtls_md_type_t md_alg, unsigned int hashlen,
 172                     const unsigned char *hash, unsigned char *sig );
 173 typedef size_t (*mbedtls_pk_rsa_alt_key_len_func)( void *ctx );
 174 #endif /* MBEDTLS_PK_RSA_ALT_SUPPORT */
 175
 176 /**
 177  * \brief           Return information associated with the given PK type
 178  *
 179  * \param pk_type   PK type to search for.
 180  *
 181  * \return          The PK info associated with the type or NULL if not found.
 182  */
 183 const mbedtls_pk_info_t *mbedtls_pk_info_from_type( mbedtls_pk_type_t pk_type );
 184
 185 /**
 186  * \brief           Initialize a mbedtls_pk_context (as NONE)
 187  */
 188 void mbedtls_pk_init( mbedtls_pk_context *ctx );
 189
 190 /**
 191  * \brief           Free a mbedtls_pk_context
 192  */
 193 void mbedtls_pk_free( mbedtls_pk_context *ctx );
 194
 195 /**
 196  * \brief           Initialize a PK context with the information given
 197  *                  and allocates the type-specific PK subcontext.
 198  *
 199  * \param ctx       Context to initialize. Must be empty (type NONE).
 200  * \param info      Information to use
 201  *
 202  * \return          0 on success,
 203  *                  MBEDTLS_ERR_PK_BAD_INPUT_DATA on invalid input,
 204  *                  MBEDTLS_ERR_PK_ALLOC_FAILED on allocation failure.
 205  *
 206  * \note            For contexts holding an RSA-alt key, use
 207  *                  \c mbedtls_pk_setup_rsa_alt() instead.
 208  */
 209 int mbedtls_pk_setup( mbedtls_pk_context *ctx, const mbedtls_pk_info_t *info );
 210
 211 #if defined(MBEDTLS_PK_RSA_ALT_SUPPORT)
 212 /**
 213  * \brief           Initialize an RSA-alt context
 214  *
 215  * \param ctx       Context to initialize. Must be empty (type NONE).
 216  * \param key       RSA key pointer
 217  * \param decrypt_func  Decryption function
 218  * \param sign_func     Signing function
 219  * \param key_len_func  Function returning key length in bytes
 220  *
 221  * \return          0 on success, or MBEDTLS_ERR_PK_BAD_INPUT_DATA if the
 222  *                  context wasn't already initialized as RSA_ALT.
 223  *
 224  * \note            This function replaces \c mbedtls_pk_setup() for RSA-alt.
 225  */
 226 int mbedtls_pk_setup_rsa_alt( mbedtls_pk_context *ctx, void * key,
 227                          mbedtls_pk_rsa_alt_decrypt_func decrypt_func,
 228                          mbedtls_pk_rsa_alt_sign_func sign_func,
 229                          mbedtls_pk_rsa_alt_key_len_func key_len_func );
 230 #endif /* MBEDTLS_PK_RSA_ALT_SUPPORT */
 231
 232 /**
 233  * \brief           Get the size in bits of the underlying key
 234  *
 235  * \param ctx       Context to use
 236  *
 237  * \return          Key size in bits, or 0 on error
 238  */
 239 size_t mbedtls_pk_get_bitlen( const mbedtls_pk_context *ctx );
 240
 241 /**
 242  * \brief           Get the length in bytes of the underlying key
 243  * \param ctx       Context to use
 244  *
 245  * \return          Key length in bytes, or 0 on error
 246  */
 247 static inline size_t mbedtls_pk_get_len( const mbedtls_pk_context *ctx )
 248 {
 249     return( ( mbedtls_pk_get_bitlen( ctx ) + 7 ) / 8 );
 250 }
 251
 252 /**
 253  * \brief           Tell if a context can do the operation given by type
 254  *
 255  * \param ctx       Context to test
 256  * \param type      Target type
 257  *
 258  * \return          0 if context can't do the operations,
 259  *                  1 otherwise.
 260  */
 261 int mbedtls_pk_can_do( const mbedtls_pk_context *ctx, mbedtls_pk_type_t type );
 262
 263 /**
 264  * \brief           Verify signature (including padding if relevant).
 265  *
 266  * \param ctx       PK context to use
 267  * \param md_alg    Hash algorithm used (see notes)
 268  * \param hash      Hash of the message to sign
 269  * \param hash_len  Hash length or 0 (see notes)
 270  * \param sig       Signature to verify
 271  * \param sig_len   Signature length
 272  *
 273  * \return          0 on success (signature is valid),
 274  *                  #MBEDTLS_ERR_PK_SIG_LEN_MISMATCH if there is a valid
 275  *                  signature in sig but its length is less than \p siglen,
 276  *                  or a specific error code.
 277  *
 278  * \note            For RSA keys, the default padding type is PKCS#1 v1.5.
 279  *                  Use \c mbedtls_pk_verify_ext( MBEDTLS_PK_RSASSA_PSS, ... )
 280  *                  to verify RSASSA_PSS signatures.
 281  *
 282  * \note            If hash_len is 0, then the length associated with md_alg
 283  *                  is used instead, or an error returned if it is invalid.
 284  *
 285  * \note            md_alg may be MBEDTLS_MD_NONE, only if hash_len != 0
 286  */
 287 int mbedtls_pk_verify( mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
 288                const unsigned char *hash, size_t hash_len,
 289                const unsigned char *sig, size_t sig_len );
 290
 291 /**
 292  * \brief           Verify signature, with options.
 293  *                  (Includes verification of the padding depending on type.)
 294  *
 295  * \param type      Signature type (inc. possible padding type) to verify
 296  * \param options   Pointer to type-specific options, or NULL
 297  * \param ctx       PK context to use
 298  * \param md_alg    Hash algorithm used (see notes)
 299  * \param hash      Hash of the message to sign
 300  * \param hash_len  Hash length or 0 (see notes)
 301  * \param sig       Signature to verify
 302  * \param sig_len   Signature length
 303  *
 304  * \return          0 on success (signature is valid),
 305  *                  #MBEDTLS_ERR_PK_TYPE_MISMATCH if the PK context can't be
 306  *                  used for this type of signatures,
 307  *                  #MBEDTLS_ERR_PK_SIG_LEN_MISMATCH if there is a valid
 308  *                  signature in sig but its length is less than \p siglen,
 309  *                  or a specific error code.
 310  *
 311  * \note            If hash_len is 0, then the length associated with md_alg
 312  *                  is used instead, or an error returned if it is invalid.
 313  *
 314  * \note            md_alg may be MBEDTLS_MD_NONE, only if hash_len != 0
 315  *
 316  * \note            If type is MBEDTLS_PK_RSASSA_PSS, then options must point
 317  *                  to a mbedtls_pk_rsassa_pss_options structure,
 318  *                  otherwise it must be NULL.
 319  */
 320 int mbedtls_pk_verify_ext( mbedtls_pk_type_t type, const void *options,
 321                    mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
 322                    const unsigned char *hash, size_t hash_len,
 323                    const unsigned char *sig, size_t sig_len );
 324
 325 /**
 326  * \brief           Make signature, including padding if relevant.
 327  *
 328  * \param ctx       PK context to use - must hold a private key
 329  * \param md_alg    Hash algorithm used (see notes)
 330  * \param hash      Hash of the message to sign
 331  * \param hash_len  Hash length or 0 (see notes)
 332  * \param sig       Place to write the signature
 333  * \param sig_len   Number of bytes written
 334  * \param f_rng     RNG function
 335  * \param p_rng     RNG parameter
 336  *
 337  * \return          0 on success, or a specific error code.
 338  *
 339  * \note            For RSA keys, the default padding type is PKCS#1 v1.5.
 340  *                  There is no interface in the PK module to make RSASSA-PSS
 341  *                  signatures yet.
 342  *
 343  * \note            If hash_len is 0, then the length associated with md_alg
 344  *                  is used instead, or an error returned if it is invalid.
 345  *
 346  * \note            For RSA, md_alg may be MBEDTLS_MD_NONE if hash_len != 0.
 347  *                  For ECDSA, md_alg may never be MBEDTLS_MD_NONE.
 348  */
 349 int mbedtls_pk_sign( mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
 350              const unsigned char *hash, size_t hash_len,
 351              unsigned char *sig, size_t *sig_len,
 352              int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
 353
 354 /**
 355  * \brief           Decrypt message (including padding if relevant).
 356  *
 357  * \param ctx       PK context to use - must hold a private key
 358  * \param input     Input to decrypt
 359  * \param ilen      Input size
 360  * \param output    Decrypted output
 361  * \param olen      Decrypted message length
 362  * \param osize     Size of the output buffer
 363  * \param f_rng     RNG function
 364  * \param p_rng     RNG parameter
 365  *
 366  * \note            For RSA keys, the default padding type is PKCS#1 v1.5.
 367  *
 368  * \return          0 on success, or a specific error code.
 369  */
 370 int mbedtls_pk_decrypt( mbedtls_pk_context *ctx,
 371                 const unsigned char *input, size_t ilen,
 372                 unsigned char *output, size_t *olen, size_t osize,
 373                 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
 374
 375 /**
 376  * \brief           Encrypt message (including padding if relevant).
 377  *
 378  * \param ctx       PK context to use
 379  * \param input     Message to encrypt
 380  * \param ilen      Message size
 381  * \param output    Encrypted output
 382  * \param olen      Encrypted output length
 383  * \param osize     Size of the output buffer
 384  * \param f_rng     RNG function
 385  * \param p_rng     RNG parameter
 386  *
 387  * \note            For RSA keys, the default padding type is PKCS#1 v1.5.
 388  *
 389  * \return          0 on success, or a specific error code.
 390  */
 391 int mbedtls_pk_encrypt( mbedtls_pk_context *ctx,
 392                 const unsigned char *input, size_t ilen,
 393                 unsigned char *output, size_t *olen, size_t osize,
 394                 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
 395
 396 /**
 397  * \brief           Check if a public-private pair of keys matches.
 398  *
 399  * \param pub       Context holding a public key.
 400  * \param prv       Context holding a private (and public) key.
 401  *
 402  * \return          0 on success or MBEDTLS_ERR_PK_BAD_INPUT_DATA
 403  */
 404 int mbedtls_pk_check_pair( const mbedtls_pk_context *pub, const mbedtls_pk_context *prv );
 405
 406 /**
 407  * \brief           Export debug information
 408  *
 409  * \param ctx       Context to use
 410  * \param items     Place to write debug items
 411  *
 412  * \return          0 on success or MBEDTLS_ERR_PK_BAD_INPUT_DATA
 413  */
 414 int mbedtls_pk_debug( const mbedtls_pk_context *ctx, mbedtls_pk_debug_item *items );
 415
 416 /**
 417  * \brief           Access the type name
 418  *
 419  * \param ctx       Context to use
 420  *
 421  * \return          Type name on success, or "invalid PK"
 422  */
 423 const char * mbedtls_pk_get_name( const mbedtls_pk_context *ctx );
 424
 425 /**
 426  * \brief           Get the key type
 427  *
 428  * \param ctx       Context to use
 429  *
 430  * \return          Type on success, or MBEDTLS_PK_NONE
 431  */
 432 mbedtls_pk_type_t mbedtls_pk_get_type( const mbedtls_pk_context *ctx );
 433
 434 #if defined(MBEDTLS_PK_PARSE_C)
 435 /** \ingroup pk_module */
 436 /**
 437  * \brief           Parse a private key in PEM or DER format
 438  *
 439  * \param ctx       key to be initialized
 440  * \param key       input buffer
 441  * \param keylen    size of the buffer
 442  *                  (including the terminating null byte for PEM data)
 443  * \param pwd       password for decryption (optional)
 444  * \param pwdlen    size of the password
 445  *
 446  * \note            On entry, ctx must be empty, either freshly initialised
 447  *                  with mbedtls_pk_init() or reset with mbedtls_pk_free(). If you need a
 448  *                  specific key type, check the result with mbedtls_pk_can_do().
 449  *
 450  * \note            The key is also checked for correctness.
 451  *
 452  * \return          0 if successful, or a specific PK or PEM error code
 453  */
 454 int mbedtls_pk_parse_key( mbedtls_pk_context *ctx,
 455                   const unsigned char *key, size_t keylen,
 456                   const unsigned char *pwd, size_t pwdlen );
 457
 458 /** \ingroup pk_module */
 459 /**
 460  * \brief           Parse a public key in PEM or DER format
 461  *
 462  * \param ctx       key to be initialized
 463  * \param key       input buffer
 464  * \param keylen    size of the buffer
 465  *                  (including the terminating null byte for PEM data)
 466  *
 467  * \note            On entry, ctx must be empty, either freshly initialised
 468  *                  with mbedtls_pk_init() or reset with mbedtls_pk_free(). If you need a
 469  *                  specific key type, check the result with mbedtls_pk_can_do().
 470  *
 471  * \note            The key is also checked for correctness.
 472  *
 473  * \return          0 if successful, or a specific PK or PEM error code
 474  */
 475 int mbedtls_pk_parse_public_key( mbedtls_pk_context *ctx,
 476                          const unsigned char *key, size_t keylen );
 477
 478 #if defined(MBEDTLS_FS_IO)
 479 /** \ingroup pk_module */
 480 /**
 481  * \brief           Load and parse a private key
 482  *
 483  * \param ctx       key to be initialized
 484  * \param path      filename to read the private key from
 485  * \param password  password to decrypt the file (can be NULL)
 486  *
 487  * \note            On entry, ctx must be empty, either freshly initialised
 488  *                  with mbedtls_pk_init() or reset with mbedtls_pk_free(). If you need a
 489  *                  specific key type, check the result with mbedtls_pk_can_do().
 490  *
 491  * \note            The key is also checked for correctness.
 492  *
 493  * \return          0 if successful, or a specific PK or PEM error code
 494  */
 495 int mbedtls_pk_parse_keyfile( mbedtls_pk_context *ctx,
 496                       const char *path, const char *password );
 497
 498 /** \ingroup pk_module */
 499 /**
 500  * \brief           Load and parse a public key
 501  *
 502  * \param ctx       key to be initialized
 503  * \param path      filename to read the public key from
 504  *
 505  * \note            On entry, ctx must be empty, either freshly initialised
 506  *                  with mbedtls_pk_init() or reset with mbedtls_pk_free(). If
 507  *                  you need a specific key type, check the result with
 508  *                  mbedtls_pk_can_do().
 509  *
 510  * \note            The key is also checked for correctness.
 511  *
 512  * \return          0 if successful, or a specific PK or PEM error code
 513  */
 514 int mbedtls_pk_parse_public_keyfile( mbedtls_pk_context *ctx, const char *path );
 515 #endif /* MBEDTLS_FS_IO */
 516 #endif /* MBEDTLS_PK_PARSE_C */
 517
 518 #if defined(MBEDTLS_PK_WRITE_C)
 519 /**
 520  * \brief           Write a private key to a PKCS#1 or SEC1 DER structure
 521  *                  Note: data is written at the end of the buffer! Use the
 522  *                        return value to determine where you should start
 523  *                        using the buffer
 524  *
 525  * \param ctx       private to write away
 526  * \param buf       buffer to write to
 527  * \param size      size of the buffer
 528  *
 529  * \return          length of data written if successful, or a specific
 530  *                  error code
 531  */
 532 int mbedtls_pk_write_key_der( mbedtls_pk_context *ctx, unsigned char *buf, size_t size );
 533
 534 /**
 535  * \brief           Write a public key to a SubjectPublicKeyInfo DER structure
 536  *                  Note: data is written at the end of the buffer! Use the
 537  *                        return value to determine where you should start
 538  *                        using the buffer
 539  *
 540  * \param ctx       public key to write away
 541  * \param buf       buffer to write to
 542  * \param size      size of the buffer
 543  *
 544  * \return          length of data written if successful, or a specific
 545  *                  error code
 546  */
 547 int mbedtls_pk_write_pubkey_der( mbedtls_pk_context *ctx, unsigned char *buf, size_t size );
 548
 549 #if defined(MBEDTLS_PEM_WRITE_C)
 550 /**
 551  * \brief           Write a public key to a PEM string
 552  *
 553  * \param ctx       public key to write away
 554  * \param buf       buffer to write to
 555  * \param size      size of the buffer
 556  *
 557  * \return          0 if successful, or a specific error code
 558  */
 559 int mbedtls_pk_write_pubkey_pem( mbedtls_pk_context *ctx, unsigned char *buf, size_t size );
 560
 561 /**
 562  * \brief           Write a private key to a PKCS#1 or SEC1 PEM string
 563  *
 564  * \param ctx       private to write away
 565  * \param buf       buffer to write to
 566  * \param size      size of the buffer
 567  *
 568  * \return          0 if successful, or a specific error code
 569  */
 570 int mbedtls_pk_write_key_pem( mbedtls_pk_context *ctx, unsigned char *buf, size_t size );
 571 #endif /* MBEDTLS_PEM_WRITE_C */
 572 #endif /* MBEDTLS_PK_WRITE_C */
 573
 574 /*
 575  * WARNING: Low-level functions. You probably do not want to use these unless
 576  *          you are certain you do ;)
 577  */
 578
 579 #if defined(MBEDTLS_PK_PARSE_C)
 580 /**
 581  * \brief           Parse a SubjectPublicKeyInfo DER structure
 582  *
 583  * \param p         the position in the ASN.1 data
 584  * \param end       end of the buffer
 585  * \param pk        the key to fill
 586  *
 587  * \return          0 if successful, or a specific PK error code
 588  */
 589 int mbedtls_pk_parse_subpubkey( unsigned char **p, const unsigned char *end,
 590                         mbedtls_pk_context *pk );
 591 #endif /* MBEDTLS_PK_PARSE_C */
 592
 593 #if defined(MBEDTLS_PK_WRITE_C)
 594 /**
 595  * \brief           Write a subjectPublicKey to ASN.1 data
 596  *                  Note: function works backwards in data buffer
 597  *
 598  * \param p         reference to current position pointer
 599  * \param start     start of the buffer (for bounds-checking)
 600  * \param key       public key to write away
 601  *
 602  * \return          the length written or a negative error code
 603  */
 604 int mbedtls_pk_write_pubkey( unsigned char **p, unsigned char *start,
 605                      const mbedtls_pk_context *key );
 606 #endif /* MBEDTLS_PK_WRITE_C */
 607
 608 /*
 609  * Internal module functions. You probably do not want to use these unless you
 610  * know you do.
 611  */
 612 #if defined(MBEDTLS_FS_IO)
 613 int mbedtls_pk_load_file( const char *path, unsigned char **buf, size_t *n );
 614 #endif
 615
 616 #ifdef __cplusplus
 617 }
 618 #endif
 619
 620 #endif /* MBEDTLS_PK_H */