cipher.h

00001 /**
00002  * \file cipher.h
00003  *
00004  * \brief Generic cipher wrapper.
00005  *
00006  * \author Adriaan de Jong <dejong@fox-it.com>
00007  *
00008  *  Copyright (C) 2006-2014, Brainspark B.V.
00009  *
00010  *  This file is part of PolarSSL (http://www.polarssl.org)
00011  *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
00012  *
00013  *  All rights reserved.
00014  *
00015  *  This program is free software; you can redistribute it and/or modify
00016  *  it under the terms of the GNU General Public License as published by
00017  *  the Free Software Foundation; either version 2 of the License, or
00018  *  (at your option) any later version.
00019  *
00020  *  This program is distributed in the hope that it will be useful,
00021  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
00022  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00023  *  GNU General Public License for more details.
00024  *
00025  *  You should have received a copy of the GNU General Public License along
00026  *  with this program; if not, write to the Free Software Foundation, Inc.,
00027  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
00028  */
00029 
00030 #ifndef POLARSSL_CIPHER_H
00031 #define POLARSSL_CIPHER_H
00032 
00033 #if !defined(POLARSSL_CONFIG_FILE)
00034 #include "config.h"
00035 #else
00036 #include POLARSSL_CONFIG_FILE
00037 #endif
00038 
00039 #if defined(POLARSSL_GCM_C)
00040 #define POLARSSL_CIPHER_MODE_AEAD
00041 #endif
00042 
00043 #if defined(POLARSSL_CIPHER_MODE_CBC)
00044 #define POLARSSL_CIPHER_MODE_WITH_PADDING
00045 #endif
00046 
00047 #include <string.h>
00048 
00049 #if defined(_MSC_VER) && !defined(inline)
00050 #define inline _inline
00051 #else
00052 #if defined(__ARMCC_VERSION) && !defined(inline)
00053 #define inline __inline
00054 #endif /* __ARMCC_VERSION */
00055 #endif /*_MSC_VER */
00056 
00057 #define POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE            -0x6080  /**< The selected feature is not available. */
00058 #define POLARSSL_ERR_CIPHER_BAD_INPUT_DATA                 -0x6100  /**< Bad input parameters to function. */
00059 #define POLARSSL_ERR_CIPHER_ALLOC_FAILED                   -0x6180  /**< Failed to allocate memory. */
00060 #define POLARSSL_ERR_CIPHER_INVALID_PADDING                -0x6200  /**< Input data contains invalid padding and is rejected. */
00061 #define POLARSSL_ERR_CIPHER_FULL_BLOCK_EXPECTED            -0x6280  /**< Decryption of block requires a full block. */
00062 #define POLARSSL_ERR_CIPHER_AUTH_FAILED                    -0x6300  /**< Authentication failed (for AEAD modes). */
00063 
00064 #ifdef __cplusplus
00065 extern "C" {
00066 #endif
00067 
00068 typedef enum {
00069     POLARSSL_CIPHER_ID_NONE = 0,
00070     POLARSSL_CIPHER_ID_NULL,
00071     POLARSSL_CIPHER_ID_AES,
00072     POLARSSL_CIPHER_ID_DES,
00073     POLARSSL_CIPHER_ID_3DES,
00074     POLARSSL_CIPHER_ID_CAMELLIA,
00075     POLARSSL_CIPHER_ID_BLOWFISH,
00076     POLARSSL_CIPHER_ID_ARC4,
00077 } cipher_id_t;
00078 
00079 typedef enum {
00080     POLARSSL_CIPHER_NONE = 0,
00081     POLARSSL_CIPHER_NULL,
00082     POLARSSL_CIPHER_AES_128_ECB,
00083     POLARSSL_CIPHER_AES_192_ECB,
00084     POLARSSL_CIPHER_AES_256_ECB,
00085     POLARSSL_CIPHER_AES_128_CBC,
00086     POLARSSL_CIPHER_AES_192_CBC,
00087     POLARSSL_CIPHER_AES_256_CBC,
00088     POLARSSL_CIPHER_AES_128_CFB128,
00089     POLARSSL_CIPHER_AES_192_CFB128,
00090     POLARSSL_CIPHER_AES_256_CFB128,
00091     POLARSSL_CIPHER_AES_128_CTR,
00092     POLARSSL_CIPHER_AES_192_CTR,
00093     POLARSSL_CIPHER_AES_256_CTR,
00094     POLARSSL_CIPHER_AES_128_GCM,
00095     POLARSSL_CIPHER_AES_192_GCM,
00096     POLARSSL_CIPHER_AES_256_GCM,
00097     POLARSSL_CIPHER_CAMELLIA_128_ECB,
00098     POLARSSL_CIPHER_CAMELLIA_192_ECB,
00099     POLARSSL_CIPHER_CAMELLIA_256_ECB,
00100     POLARSSL_CIPHER_CAMELLIA_128_CBC,
00101     POLARSSL_CIPHER_CAMELLIA_192_CBC,
00102     POLARSSL_CIPHER_CAMELLIA_256_CBC,
00103     POLARSSL_CIPHER_CAMELLIA_128_CFB128,
00104     POLARSSL_CIPHER_CAMELLIA_192_CFB128,
00105     POLARSSL_CIPHER_CAMELLIA_256_CFB128,
00106     POLARSSL_CIPHER_CAMELLIA_128_CTR,
00107     POLARSSL_CIPHER_CAMELLIA_192_CTR,
00108     POLARSSL_CIPHER_CAMELLIA_256_CTR,
00109     POLARSSL_CIPHER_CAMELLIA_128_GCM,
00110     POLARSSL_CIPHER_CAMELLIA_192_GCM,
00111     POLARSSL_CIPHER_CAMELLIA_256_GCM,
00112     POLARSSL_CIPHER_DES_ECB,
00113     POLARSSL_CIPHER_DES_CBC,
00114     POLARSSL_CIPHER_DES_EDE_ECB,
00115     POLARSSL_CIPHER_DES_EDE_CBC,
00116     POLARSSL_CIPHER_DES_EDE3_ECB,
00117     POLARSSL_CIPHER_DES_EDE3_CBC,
00118     POLARSSL_CIPHER_BLOWFISH_ECB,
00119     POLARSSL_CIPHER_BLOWFISH_CBC,
00120     POLARSSL_CIPHER_BLOWFISH_CFB64,
00121     POLARSSL_CIPHER_BLOWFISH_CTR,
00122     POLARSSL_CIPHER_ARC4_128,
00123 } cipher_type_t;
00124 
00125 typedef enum {
00126     POLARSSL_MODE_NONE = 0,
00127     POLARSSL_MODE_ECB,
00128     POLARSSL_MODE_CBC,
00129     POLARSSL_MODE_CFB,
00130     POLARSSL_MODE_OFB,
00131     POLARSSL_MODE_CTR,
00132     POLARSSL_MODE_GCM,
00133     POLARSSL_MODE_STREAM,
00134 } cipher_mode_t;
00135 
00136 typedef enum {
00137     POLARSSL_PADDING_PKCS7 = 0,     /**< PKCS7 padding (default)        */
00138     POLARSSL_PADDING_ONE_AND_ZEROS, /**< ISO/IEC 7816-4 padding         */
00139     POLARSSL_PADDING_ZEROS_AND_LEN, /**< ANSI X.923 padding             */
00140     POLARSSL_PADDING_ZEROS,         /**< zero padding (not reversible!) */
00141     POLARSSL_PADDING_NONE,          /**< never pad (full blocks only)   */
00142 } cipher_padding_t ;
00143 
00144 typedef enum {
00145     POLARSSL_OPERATION_NONE = -1,
00146     POLARSSL_DECRYPT = 0,
00147     POLARSSL_ENCRYPT,
00148 } operation_t;
00149 
00150 enum {
00151     /** Undefined key length */
00152     POLARSSL_KEY_LENGTH_NONE = 0,
00153     /** Key length, in bits (including parity), for DES keys */
00154     POLARSSL_KEY_LENGTH_DES  = 64,
00155     /** Key length, in bits (including parity), for DES in two key EDE */
00156     POLARSSL_KEY_LENGTH_DES_EDE = 128,
00157     /** Key length, in bits (including parity), for DES in three-key EDE */
00158     POLARSSL_KEY_LENGTH_DES_EDE3 = 192,
00159 };
00160 
00161 /** Maximum length of any IV, in bytes */
00162 #define POLARSSL_MAX_IV_LENGTH      16
00163 /** Maximum block size of any cipher, in bytes */
00164 #define POLARSSL_MAX_BLOCK_LENGTH   16
00165 
00166 /**
00167  * Base cipher information. The non-mode specific functions and values.
00168  */
00169 typedef struct {
00170 
00171     /** Base Cipher type (e.g. POLARSSL_CIPHER_ID_AES) */
00172     cipher_id_t cipher;
00173 
00174     /** Encrypt using ECB */
00175     int (*ecb_func)( void *ctx, operation_t mode,
00176                      const unsigned char *input, unsigned char *output );
00177 
00178     /** Encrypt using CBC */
00179     int (*cbc_func)( void *ctx, operation_t mode, size_t length,
00180                      unsigned char *iv, const unsigned char *input,
00181                      unsigned char *output );
00182 
00183     /** Encrypt using CFB (Full length) */
00184     int (*cfb_func)( void *ctx, operation_t mode, size_t length, size_t *iv_off,
00185                      unsigned char *iv, const unsigned char *input,
00186                      unsigned char *output );
00187 
00188     /** Encrypt using CTR */
00189     int (*ctr_func)( void *ctx, size_t length, size_t *nc_off,
00190                      unsigned char *nonce_counter, unsigned char *stream_block,
00191                      const unsigned char *input, unsigned char *output );
00192 
00193     /** Encrypt using STREAM */
00194     int (*stream_func)( void *ctx, size_t length,
00195                         const unsigned char *input, unsigned char *output );
00196 
00197     /** Set key for encryption purposes */
00198     int (*setkey_enc_func)( void *ctx, const unsigned char *key,
00199                             unsigned int key_length );
00200 
00201     /** Set key for decryption purposes */
00202     int (*setkey_dec_func)( void *ctx, const unsigned char *key,
00203                             unsigned int key_length);
00204 
00205     /** Allocate a new context */
00206     void * (*ctx_alloc_func)( void );
00207 
00208     /** Free the given context */
00209     void (*ctx_free_func)( void *ctx );
00210 
00211 } cipher_base_t;
00212 
00213 /**
00214  * Cipher information. Allows cipher functions to be called in a generic way.
00215  */
00216 typedef struct {
00217     /** Full cipher identifier (e.g. POLARSSL_CIPHER_AES_256_CBC) */
00218     cipher_type_t type;
00219 
00220     /** Cipher mode (e.g. POLARSSL_MODE_CBC) */
00221     cipher_mode_t mode;
00222 
00223     /** Cipher key length, in bits (default length for variable sized ciphers)
00224      *  (Includes parity bits for ciphers like DES) */
00225     unsigned int key_length;
00226 
00227     /** Name of the cipher */
00228     const char * name;
00229 
00230     /** IV/NONCE size, in bytes.
00231      *  For cipher that accept many sizes: recommended size */
00232     unsigned int iv_size;
00233 
00234     /** Flag for ciphers that accept many sizes of IV/NONCE */
00235     int accepts_variable_iv_size;
00236 
00237     /** block size, in bytes */
00238     unsigned int block_size;
00239 
00240     /** Base cipher information and functions */
00241     const cipher_base_t *base;
00242 
00243 } cipher_info_t;
00244 
00245 /**
00246  * Generic cipher context.
00247  */
00248 typedef struct {
00249     /** Information about the associated cipher */
00250     const cipher_info_t *cipher_info;
00251 
00252     /** Key length to use */
00253     int key_length;
00254 
00255     /** Operation that the context's key has been initialised for */
00256     operation_t operation;
00257 
00258     /** Padding functions to use, if relevant for cipher mode */
00259     void (*add_padding)( unsigned char *output, size_t olen, size_t data_len );
00260     int (*get_padding)( unsigned char *input, size_t ilen, size_t *data_len );
00261 
00262     /** Buffer for data that hasn't been encrypted yet */
00263     unsigned char unprocessed_data[POLARSSL_MAX_BLOCK_LENGTH];
00264 
00265     /** Number of bytes that still need processing */
00266     size_t unprocessed_len;
00267 
00268     /** Current IV or NONCE_COUNTER for CTR-mode */
00269     unsigned char iv[POLARSSL_MAX_IV_LENGTH];
00270 
00271     /** IV size in bytes (for ciphers with variable-length IVs) */
00272     size_t iv_size;
00273 
00274     /** Cipher-specific context */
00275     void *cipher_ctx;
00276 } cipher_context_t;
00277 
00278 /**
00279  * \brief Returns the list of ciphers supported by the generic cipher module.
00280  *
00281  * \return              a statically allocated array of ciphers, the last entry
00282  *                      is 0.
00283  */
00284 const int *cipher_list( void );
00285 
00286 /**
00287  * \brief               Returns the cipher information structure associated
00288  *                      with the given cipher name.
00289  *
00290  * \param cipher_name   Name of the cipher to search for.
00291  *
00292  * \return              the cipher information structure associated with the
00293  *                      given cipher_name, or NULL if not found.
00294  */
00295 const cipher_info_t *cipher_info_from_string( const char *cipher_name );
00296 
00297 /**
00298  * \brief               Returns the cipher information structure associated
00299  *                      with the given cipher type.
00300  *
00301  * \param cipher_type   Type of the cipher to search for.
00302  *
00303  * \return              the cipher information structure associated with the
00304  *                      given cipher_type, or NULL if not found.
00305  */
00306 const cipher_info_t *cipher_info_from_type( const cipher_type_t cipher_type );
00307 
00308 /**
00309  * \brief               Returns the cipher information structure associated
00310  *                      with the given cipher id, key size and mode.
00311  *
00312  * \param cipher_id     Id of the cipher to search for
00313  *                      (e.g. POLARSSL_CIPHER_ID_AES)
00314  * \param key_length    Length of the key in bits
00315  * \param mode          Cipher mode (e.g. POLARSSL_MODE_CBC)
00316  *
00317  * \return              the cipher information structure associated with the
00318  *                      given cipher_type, or NULL if not found.
00319  */
00320 const cipher_info_t *cipher_info_from_values( const cipher_id_t cipher_id,
00321                                               int key_length,
00322                                               const cipher_mode_t mode );
00323 
00324 /**
00325  * \brief               Initialises and fills the cipher context structure with
00326  *                      the appropriate values.
00327  *
00328  * \param ctx           context to initialise. May not be NULL.
00329  * \param cipher_info   cipher to use.
00330  *
00331  * \return              0 on success,
00332  *                      POLARSSL_ERR_CIPHER_BAD_INPUT_DATA on parameter failure,
00333  *                      POLARSSL_ERR_CIPHER_ALLOC_FAILED if allocation of the
00334  *                      cipher-specific context failed.
00335  */
00336 int cipher_init_ctx( cipher_context_t *ctx, const cipher_info_t *cipher_info );
00337 
00338 /**
00339  * \brief               Free the cipher-specific context of ctx. Freeing ctx
00340  *                      itself remains the responsibility of the caller.
00341  *
00342  * \param ctx           Free the cipher-specific context
00343  *
00344  * \returns             0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if
00345  *                      parameter verification fails.
00346  */
00347 int cipher_free_ctx( cipher_context_t *ctx );
00348 
00349 /**
00350  * \brief               Returns the block size of the given cipher.
00351  *
00352  * \param ctx           cipher's context. Must have been initialised.
00353  *
00354  * \return              size of the cipher's blocks, or 0 if ctx has not been
00355  *                      initialised.
00356  */
00357 static inline unsigned int cipher_get_block_size( const cipher_context_t *ctx )
00358 {
00359     if( NULL == ctx || NULL == ctx->cipher_info )
00360         return 0;
00361 
00362     return ctx->cipher_info->block_size;
00363 }
00364 
00365 /**
00366  * \brief               Returns the mode of operation for the cipher.
00367  *                      (e.g. POLARSSL_MODE_CBC)
00368  *
00369  * \param ctx           cipher's context. Must have been initialised.
00370  *
00371  * \return              mode of operation, or POLARSSL_MODE_NONE if ctx
00372  *                      has not been initialised.
00373  */
00374 static inline cipher_mode_t cipher_get_cipher_mode( const cipher_context_t *ctx )
00375 {
00376     if( NULL == ctx || NULL == ctx->cipher_info )
00377         return POLARSSL_MODE_NONE;
00378 
00379     return ctx->cipher_info->mode;
00380 }
00381 
00382 /**
00383  * \brief               Returns the size of the cipher's IV/NONCE in bytes.
00384  *
00385  * \param ctx           cipher's context. Must have been initialised.
00386  *
00387  * \return              If IV has not been set yet: (recommended) IV size
00388  *                      (0 for ciphers not using IV/NONCE).
00389  *                      If IV has already been set: actual size.
00390  */
00391 static inline int cipher_get_iv_size( const cipher_context_t *ctx )
00392 {
00393     if( NULL == ctx || NULL == ctx->cipher_info )
00394         return 0;
00395 
00396     if( ctx->iv_size != 0 )
00397         return (int) ctx->iv_size;
00398 
00399     return ctx->cipher_info->iv_size;
00400 }
00401 
00402 /**
00403  * \brief               Returns the type of the given cipher.
00404  *
00405  * \param ctx           cipher's context. Must have been initialised.
00406  *
00407  * \return              type of the cipher, or POLARSSL_CIPHER_NONE if ctx has
00408  *                      not been initialised.
00409  */
00410 static inline cipher_type_t cipher_get_type( const cipher_context_t *ctx )
00411 {
00412     if( NULL == ctx || NULL == ctx->cipher_info )
00413         return POLARSSL_CIPHER_NONE;
00414 
00415     return ctx->cipher_info->type;
00416 }
00417 
00418 /**
00419  * \brief               Returns the name of the given cipher, as a string.
00420  *
00421  * \param ctx           cipher's context. Must have been initialised.
00422  *
00423  * \return              name of the cipher, or NULL if ctx was not initialised.
00424  */
00425 static inline const char *cipher_get_name( const cipher_context_t *ctx )
00426 {
00427     if( NULL == ctx || NULL == ctx->cipher_info )
00428         return 0;
00429 
00430     return ctx->cipher_info->name;
00431 }
00432 
00433 /**
00434  * \brief               Returns the key length of the cipher.
00435  *
00436  * \param ctx           cipher's context. Must have been initialised.
00437  *
00438  * \return              cipher's key length, in bits, or
00439  *                      POLARSSL_KEY_LENGTH_NONE if ctx has not been
00440  *                      initialised.
00441  */
00442 static inline int cipher_get_key_size ( const cipher_context_t *ctx )
00443 {
00444     if( NULL == ctx || NULL == ctx->cipher_info )
00445         return POLARSSL_KEY_LENGTH_NONE;
00446 
00447     return ctx->cipher_info->key_length;
00448 }
00449 
00450 /**
00451  * \brief               Returns the operation of the given cipher.
00452  *
00453  * \param ctx           cipher's context. Must have been initialised.
00454  *
00455  * \return              operation (POLARSSL_ENCRYPT or POLARSSL_DECRYPT),
00456  *                      or POLARSSL_OPERATION_NONE if ctx has not been
00457  *                      initialised.
00458  */
00459 static inline operation_t cipher_get_operation( const cipher_context_t *ctx )
00460 {
00461     if( NULL == ctx || NULL == ctx->cipher_info )
00462         return POLARSSL_OPERATION_NONE;
00463 
00464     return ctx->operation;
00465 }
00466 
00467 /**
00468  * \brief               Set the key to use with the given context.
00469  *
00470  * \param ctx           generic cipher context. May not be NULL. Must have been
00471  *                      initialised using cipher_context_from_type or
00472  *                      cipher_context_from_string.
00473  * \param key           The key to use.
00474  * \param key_length    key length to use, in bits.
00475  * \param operation     Operation that the key will be used for, either
00476  *                      POLARSSL_ENCRYPT or POLARSSL_DECRYPT.
00477  *
00478  * \returns             0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if
00479  *                      parameter verification fails or a cipher specific
00480  *                      error code.
00481  */
00482 int cipher_setkey( cipher_context_t *ctx, const unsigned char *key,
00483                    int key_length, const operation_t operation );
00484 
00485 #if defined(POLARSSL_CIPHER_MODE_WITH_PADDING)
00486 /**
00487  * \brief               Set padding mode, for cipher modes that use padding.
00488  *                      (Default: PKCS7 padding.)
00489  *
00490  * \param ctx           generic cipher context
00491  * \param mode          padding mode
00492  *
00493  * \returns             0 on success, POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE
00494  *                      if selected padding mode is not supported, or
00495  *                      POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if the cipher mode
00496  *                      does not support padding.
00497  */
00498 int cipher_set_padding_mode( cipher_context_t *ctx, cipher_padding_t  mode );
00499 #endif /* POLARSSL_CIPHER_MODE_WITH_PADDING */
00500 
00501 /**
00502  * \brief               Set the initialization vector (IV) or nonce
00503  *
00504  * \param ctx           generic cipher context
00505  * \param iv            IV to use (or NONCE_COUNTER for CTR-mode ciphers)
00506  * \param iv_len        IV length for ciphers with variable-size IV;
00507  *                      discarded by ciphers with fixed-size IV.
00508  *
00509  * \returns             O on success, or POLARSSL_ERR_CIPHER_BAD_INPUT_DATA
00510  *
00511  * \note                Some ciphers don't use IVs nor NONCE. For these
00512  *                      ciphers, this function has no effect.
00513  */
00514 int cipher_set_iv( cipher_context_t *ctx,
00515                    const unsigned char *iv, size_t iv_len );
00516 
00517 /**
00518  * \brief               Finish preparation of the given context
00519  *
00520  * \param ctx           generic cipher context
00521  *
00522  * \returns             0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA
00523  *                      if parameter verification fails.
00524  */
00525 int cipher_reset( cipher_context_t *ctx );
00526 
00527 #if defined(POLARSSL_CIPHER_MODE_AEAD)
00528 /**
00529  * \brief               Add additional data (for AEAD ciphers).
00530  *                      This function has no effect for non-AEAD ciphers.
00531  *                      For AEAD ciphers, it may or may not be called
00532  *                      repeatedly, and/or interleaved with calls to
00533  *                      cipher_udpate(), depending on the cipher.
00534  *                      E.g. for GCM is must be called exactly once, right
00535  *                      after cipher_reset().
00536  *
00537  * \param ctx           generic cipher context
00538  * \param ad            Additional data to use.
00539  * \param ad_len        Length of ad.
00540  *
00541  * \returns             0 on success, or a specific error code.
00542  */
00543 int cipher_update_ad( cipher_context_t *ctx,
00544                       const unsigned char *ad, size_t ad_len );
00545 #endif /* POLARSSL_CIPHER_MODE_AEAD */
00546 
00547 /**
00548  * \brief               Generic cipher update function. Encrypts/decrypts
00549  *                      using the given cipher context. Writes as many block
00550  *                      size'd blocks of data as possible to output. Any data
00551  *                      that cannot be written immediately will either be added
00552  *                      to the next block, or flushed when cipher_final is
00553  *                      called.
00554  *                      Exception: for POLARSSL_MODE_ECB, expects single block
00555  *                                 in size (e.g. 16 bytes for AES)
00556  *
00557  * \param ctx           generic cipher context
00558  * \param input         buffer holding the input data
00559  * \param ilen          length of the input data
00560  * \param output        buffer for the output data. Should be able to hold at
00561  *                      least ilen + block_size. Cannot be the same buffer as
00562  *                      input!
00563  * \param olen          length of the output data, will be filled with the
00564  *                      actual number of bytes written.
00565  *
00566  * \returns             0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if
00567  *                      parameter verification fails,
00568  *                      POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE on an
00569  *                      unsupported mode for a cipher or a cipher specific
00570  *                      error code.
00571  *
00572  * \note                If the underlying cipher is GCM, all calls to this
00573  *                      function, except the last one before cipher_finish(),
00574  *                      must have ilen a multiple of the block size.
00575  */
00576 int cipher_update( cipher_context_t *ctx, const unsigned char *input,
00577                    size_t ilen, unsigned char *output, size_t *olen );
00578 
00579 /**
00580  * \brief               Generic cipher finalisation function. If data still
00581  *                      needs to be flushed from an incomplete block, data
00582  *                      contained within it will be padded with the size of
00583  *                      the last block, and written to the output buffer.
00584  *
00585  * \param ctx           Generic cipher context
00586  * \param output        buffer to write data to. Needs block_size available.
00587  * \param olen          length of the data written to the output buffer.
00588  *
00589  * \returns             0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if
00590  *                      parameter verification fails,
00591  *                      POLARSSL_ERR_CIPHER_FULL_BLOCK_EXPECTED if decryption
00592  *                      expected a full block but was not provided one,
00593  *                      POLARSSL_ERR_CIPHER_INVALID_PADDING on invalid padding
00594  *                      while decrypting or a cipher specific error code.
00595  */
00596 int cipher_finish( cipher_context_t *ctx,
00597                    unsigned char *output, size_t *olen );
00598 
00599 #if defined(POLARSSL_CIPHER_MODE_AEAD)
00600 /**
00601  * \brief               Write tag for AEAD ciphers.
00602  *                      No effect for other ciphers.
00603  *                      Must be called after cipher_finish().
00604  *
00605  * \param ctx           Generic cipher context
00606  * \param tag           buffer to write the tag
00607  * \param tag_len       Length of the tag to write
00608  *
00609  * \return              0 on success, or a specific error code.
00610  */
00611 int cipher_write_tag( cipher_context_t *ctx,
00612                       unsigned char *tag, size_t tag_len );
00613 
00614 /**
00615  * \brief               Check tag for AEAD ciphers.
00616  *                      No effect for other ciphers.
00617  *                      Calling time depends on the cipher:
00618  *                      for GCM, must be called after cipher_finish().
00619  *
00620  * \param ctx           Generic cipher context
00621  * \param tag           Buffer holding the tag
00622  * \param tag_len       Length of the tag to check
00623  *
00624  * \return              0 on success, or a specific error code.
00625  */
00626 int cipher_check_tag( cipher_context_t *ctx,
00627                       const unsigned char *tag, size_t tag_len );
00628 #endif /* POLARSSL_CIPHER_MODE_AEAD */
00629 
00630 /**
00631  * \brief          Checkup routine
00632  *
00633  * \return         0 if successful, or 1 if the test failed
00634  */
00635 int cipher_self_test( int verbose );
00636 
00637 #ifdef __cplusplus
00638 }
00639 #endif
00640 
00641 #endif /* POLARSSL_CIPHER_H */
00642 
00643