cipher.h

00001 /**
00002  * \file cipher.h
00003  *
00004  * \brief This file contains an abstraction interface for use with the cipher
00005  * primitives provided by the library. It provides a common interface to all of
00006  * the available cipher operations.
00007  *
00008  * \author Adriaan de Jong <dejong@fox-it.com>
00009  */
00010 /*
00011  *  Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
00012  *  SPDX-License-Identifier: Apache-2.0
00013  *
00014  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
00015  *  not use this file except in compliance with the License.
00016  *  You may obtain a copy of the License at
00017  *
00018  *  http://www.apache.org/licenses/LICENSE-2.0
00019  *
00020  *  Unless required by applicable law or agreed to in writing, software
00021  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
00022  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00023  *  See the License for the specific language governing permissions and
00024  *  limitations under the License.
00025  *
00026  *  This file is part of Mbed TLS (https://tls.mbed.org)
00027  */
00028 
00029 #ifndef MBEDTLS_CIPHER_H
00030 #define MBEDTLS_CIPHER_H
00031 
00032 #if !defined(MBEDTLS_CONFIG_FILE)
00033 #include "mbedtls/config.h"
00034 #else
00035 #include MBEDTLS_CONFIG_FILE
00036 #endif
00037 
00038 #include <stddef.h>
00039 #include "mbedtls/platform_util.h"
00040 
00041 #if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
00042 #define MBEDTLS_CIPHER_MODE_AEAD
00043 #endif
00044 
00045 #if defined(MBEDTLS_CIPHER_MODE_CBC)
00046 #define MBEDTLS_CIPHER_MODE_WITH_PADDING
00047 #endif
00048 
00049 #if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER) || \
00050     defined(MBEDTLS_CHACHA20_C)
00051 #define MBEDTLS_CIPHER_MODE_STREAM
00052 #endif
00053 
00054 #if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
00055     !defined(inline) && !defined(__cplusplus)
00056 #define inline __inline
00057 #endif
00058 
00059 #define MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE  -0x6080  /**< The selected feature is not available. */
00060 #define MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA       -0x6100  /**< Bad input parameters. */
00061 #define MBEDTLS_ERR_CIPHER_ALLOC_FAILED         -0x6180  /**< Failed to allocate memory. */
00062 #define MBEDTLS_ERR_CIPHER_INVALID_PADDING      -0x6200  /**< Input data contains invalid padding and is rejected. */
00063 #define MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED  -0x6280  /**< Decryption of block requires a full block. */
00064 #define MBEDTLS_ERR_CIPHER_AUTH_FAILED          -0x6300  /**< Authentication failed (for AEAD modes). */
00065 #define MBEDTLS_ERR_CIPHER_INVALID_CONTEXT      -0x6380  /**< The context is invalid. For example, because it was freed. */
00066 
00067 /* MBEDTLS_ERR_CIPHER_HW_ACCEL_FAILED is deprecated and should not be used. */
00068 #define MBEDTLS_ERR_CIPHER_HW_ACCEL_FAILED      -0x6400  /**< Cipher hardware accelerator failed. */
00069 
00070 #define MBEDTLS_CIPHER_VARIABLE_IV_LEN     0x01    /**< Cipher accepts IVs of variable length. */
00071 #define MBEDTLS_CIPHER_VARIABLE_KEY_LEN    0x02    /**< Cipher accepts keys of variable length. */
00072 
00073 #ifdef __cplusplus
00074 extern "C" {
00075 #endif
00076 
00077 /**
00078  * \brief     Supported cipher types.
00079  *
00080  * \warning   RC4 and DES are considered weak ciphers and their use
00081  *            constitutes a security risk. Arm recommends considering stronger
00082  *            ciphers instead.
00083  */
00084 typedef enum {
00085     MBEDTLS_CIPHER_ID_NONE = 0,  /**< Placeholder to mark the end of cipher ID lists. */
00086     MBEDTLS_CIPHER_ID_NULL,      /**< The identity cipher, treated as a stream cipher. */
00087     MBEDTLS_CIPHER_ID_AES,       /**< The AES cipher. */
00088     MBEDTLS_CIPHER_ID_DES,       /**< The DES cipher. */
00089     MBEDTLS_CIPHER_ID_3DES,      /**< The Triple DES cipher. */
00090     MBEDTLS_CIPHER_ID_CAMELLIA,  /**< The Camellia cipher. */
00091     MBEDTLS_CIPHER_ID_BLOWFISH,  /**< The Blowfish cipher. */
00092     MBEDTLS_CIPHER_ID_ARC4,      /**< The RC4 cipher. */
00093     MBEDTLS_CIPHER_ID_ARIA,      /**< The Aria cipher. */
00094     MBEDTLS_CIPHER_ID_CHACHA20,  /**< The ChaCha20 cipher. */
00095 } mbedtls_cipher_id_t;
00096 
00097 /**
00098  * \brief     Supported {cipher type, cipher mode} pairs.
00099  *
00100  * \warning   RC4 and DES are considered weak ciphers and their use
00101  *            constitutes a security risk. Arm recommends considering stronger
00102  *            ciphers instead.
00103  */
00104 typedef enum {
00105     MBEDTLS_CIPHER_NONE = 0,             /**< Placeholder to mark the end of cipher-pair lists. */
00106     MBEDTLS_CIPHER_NULL,                 /**< The identity stream cipher. */
00107     MBEDTLS_CIPHER_AES_128_ECB,          /**< AES cipher with 128-bit ECB mode. */
00108     MBEDTLS_CIPHER_AES_192_ECB,          /**< AES cipher with 192-bit ECB mode. */
00109     MBEDTLS_CIPHER_AES_256_ECB,          /**< AES cipher with 256-bit ECB mode. */
00110     MBEDTLS_CIPHER_AES_128_CBC,          /**< AES cipher with 128-bit CBC mode. */
00111     MBEDTLS_CIPHER_AES_192_CBC,          /**< AES cipher with 192-bit CBC mode. */
00112     MBEDTLS_CIPHER_AES_256_CBC,          /**< AES cipher with 256-bit CBC mode. */
00113     MBEDTLS_CIPHER_AES_128_CFB128,       /**< AES cipher with 128-bit CFB128 mode. */
00114     MBEDTLS_CIPHER_AES_192_CFB128,       /**< AES cipher with 192-bit CFB128 mode. */
00115     MBEDTLS_CIPHER_AES_256_CFB128,       /**< AES cipher with 256-bit CFB128 mode. */
00116     MBEDTLS_CIPHER_AES_128_CTR,          /**< AES cipher with 128-bit CTR mode. */
00117     MBEDTLS_CIPHER_AES_192_CTR,          /**< AES cipher with 192-bit CTR mode. */
00118     MBEDTLS_CIPHER_AES_256_CTR,          /**< AES cipher with 256-bit CTR mode. */
00119     MBEDTLS_CIPHER_AES_128_GCM,          /**< AES cipher with 128-bit GCM mode. */
00120     MBEDTLS_CIPHER_AES_192_GCM,          /**< AES cipher with 192-bit GCM mode. */
00121     MBEDTLS_CIPHER_AES_256_GCM,          /**< AES cipher with 256-bit GCM mode. */
00122     MBEDTLS_CIPHER_CAMELLIA_128_ECB,     /**< Camellia cipher with 128-bit ECB mode. */
00123     MBEDTLS_CIPHER_CAMELLIA_192_ECB,     /**< Camellia cipher with 192-bit ECB mode. */
00124     MBEDTLS_CIPHER_CAMELLIA_256_ECB,     /**< Camellia cipher with 256-bit ECB mode. */
00125     MBEDTLS_CIPHER_CAMELLIA_128_CBC,     /**< Camellia cipher with 128-bit CBC mode. */
00126     MBEDTLS_CIPHER_CAMELLIA_192_CBC,     /**< Camellia cipher with 192-bit CBC mode. */
00127     MBEDTLS_CIPHER_CAMELLIA_256_CBC,     /**< Camellia cipher with 256-bit CBC mode. */
00128     MBEDTLS_CIPHER_CAMELLIA_128_CFB128,  /**< Camellia cipher with 128-bit CFB128 mode. */
00129     MBEDTLS_CIPHER_CAMELLIA_192_CFB128,  /**< Camellia cipher with 192-bit CFB128 mode. */
00130     MBEDTLS_CIPHER_CAMELLIA_256_CFB128,  /**< Camellia cipher with 256-bit CFB128 mode. */
00131     MBEDTLS_CIPHER_CAMELLIA_128_CTR,     /**< Camellia cipher with 128-bit CTR mode. */
00132     MBEDTLS_CIPHER_CAMELLIA_192_CTR,     /**< Camellia cipher with 192-bit CTR mode. */
00133     MBEDTLS_CIPHER_CAMELLIA_256_CTR,     /**< Camellia cipher with 256-bit CTR mode. */
00134     MBEDTLS_CIPHER_CAMELLIA_128_GCM,     /**< Camellia cipher with 128-bit GCM mode. */
00135     MBEDTLS_CIPHER_CAMELLIA_192_GCM,     /**< Camellia cipher with 192-bit GCM mode. */
00136     MBEDTLS_CIPHER_CAMELLIA_256_GCM,     /**< Camellia cipher with 256-bit GCM mode. */
00137     MBEDTLS_CIPHER_DES_ECB,              /**< DES cipher with ECB mode. */
00138     MBEDTLS_CIPHER_DES_CBC,              /**< DES cipher with CBC mode. */
00139     MBEDTLS_CIPHER_DES_EDE_ECB,          /**< DES cipher with EDE ECB mode. */
00140     MBEDTLS_CIPHER_DES_EDE_CBC,          /**< DES cipher with EDE CBC mode. */
00141     MBEDTLS_CIPHER_DES_EDE3_ECB,         /**< DES cipher with EDE3 ECB mode. */
00142     MBEDTLS_CIPHER_DES_EDE3_CBC,         /**< DES cipher with EDE3 CBC mode. */
00143     MBEDTLS_CIPHER_BLOWFISH_ECB,         /**< Blowfish cipher with ECB mode. */
00144     MBEDTLS_CIPHER_BLOWFISH_CBC,         /**< Blowfish cipher with CBC mode. */
00145     MBEDTLS_CIPHER_BLOWFISH_CFB64,       /**< Blowfish cipher with CFB64 mode. */
00146     MBEDTLS_CIPHER_BLOWFISH_CTR,         /**< Blowfish cipher with CTR mode. */
00147     MBEDTLS_CIPHER_ARC4_128,             /**< RC4 cipher with 128-bit mode. */
00148     MBEDTLS_CIPHER_AES_128_CCM,          /**< AES cipher with 128-bit CCM mode. */
00149     MBEDTLS_CIPHER_AES_192_CCM,          /**< AES cipher with 192-bit CCM mode. */
00150     MBEDTLS_CIPHER_AES_256_CCM,          /**< AES cipher with 256-bit CCM mode. */
00151     MBEDTLS_CIPHER_CAMELLIA_128_CCM,     /**< Camellia cipher with 128-bit CCM mode. */
00152     MBEDTLS_CIPHER_CAMELLIA_192_CCM,     /**< Camellia cipher with 192-bit CCM mode. */
00153     MBEDTLS_CIPHER_CAMELLIA_256_CCM,     /**< Camellia cipher with 256-bit CCM mode. */
00154     MBEDTLS_CIPHER_ARIA_128_ECB,         /**< Aria cipher with 128-bit key and ECB mode. */
00155     MBEDTLS_CIPHER_ARIA_192_ECB,         /**< Aria cipher with 192-bit key and ECB mode. */
00156     MBEDTLS_CIPHER_ARIA_256_ECB,         /**< Aria cipher with 256-bit key and ECB mode. */
00157     MBEDTLS_CIPHER_ARIA_128_CBC,         /**< Aria cipher with 128-bit key and CBC mode. */
00158     MBEDTLS_CIPHER_ARIA_192_CBC,         /**< Aria cipher with 192-bit key and CBC mode. */
00159     MBEDTLS_CIPHER_ARIA_256_CBC,         /**< Aria cipher with 256-bit key and CBC mode. */
00160     MBEDTLS_CIPHER_ARIA_128_CFB128,      /**< Aria cipher with 128-bit key and CFB-128 mode. */
00161     MBEDTLS_CIPHER_ARIA_192_CFB128,      /**< Aria cipher with 192-bit key and CFB-128 mode. */
00162     MBEDTLS_CIPHER_ARIA_256_CFB128,      /**< Aria cipher with 256-bit key and CFB-128 mode. */
00163     MBEDTLS_CIPHER_ARIA_128_CTR,         /**< Aria cipher with 128-bit key and CTR mode. */
00164     MBEDTLS_CIPHER_ARIA_192_CTR,         /**< Aria cipher with 192-bit key and CTR mode. */
00165     MBEDTLS_CIPHER_ARIA_256_CTR,         /**< Aria cipher with 256-bit key and CTR mode. */
00166     MBEDTLS_CIPHER_ARIA_128_GCM,         /**< Aria cipher with 128-bit key and GCM mode. */
00167     MBEDTLS_CIPHER_ARIA_192_GCM,         /**< Aria cipher with 192-bit key and GCM mode. */
00168     MBEDTLS_CIPHER_ARIA_256_GCM,         /**< Aria cipher with 256-bit key and GCM mode. */
00169     MBEDTLS_CIPHER_ARIA_128_CCM,         /**< Aria cipher with 128-bit key and CCM mode. */
00170     MBEDTLS_CIPHER_ARIA_192_CCM,         /**< Aria cipher with 192-bit key and CCM mode. */
00171     MBEDTLS_CIPHER_ARIA_256_CCM,         /**< Aria cipher with 256-bit key and CCM mode. */
00172     MBEDTLS_CIPHER_AES_128_OFB,          /**< AES 128-bit cipher in OFB mode. */
00173     MBEDTLS_CIPHER_AES_192_OFB,          /**< AES 192-bit cipher in OFB mode. */
00174     MBEDTLS_CIPHER_AES_256_OFB,          /**< AES 256-bit cipher in OFB mode. */
00175     MBEDTLS_CIPHER_AES_128_XTS,          /**< AES 128-bit cipher in XTS block mode. */
00176     MBEDTLS_CIPHER_AES_256_XTS,          /**< AES 256-bit cipher in XTS block mode. */
00177     MBEDTLS_CIPHER_CHACHA20,             /**< ChaCha20 stream cipher. */
00178     MBEDTLS_CIPHER_CHACHA20_POLY1305,    /**< ChaCha20-Poly1305 AEAD cipher. */
00179     MBEDTLS_CIPHER_AES_128_KW,           /**< AES cipher with 128-bit NIST KW mode. */
00180     MBEDTLS_CIPHER_AES_192_KW,           /**< AES cipher with 192-bit NIST KW mode. */
00181     MBEDTLS_CIPHER_AES_256_KW,           /**< AES cipher with 256-bit NIST KW mode. */
00182     MBEDTLS_CIPHER_AES_128_KWP,          /**< AES cipher with 128-bit NIST KWP mode. */
00183     MBEDTLS_CIPHER_AES_192_KWP,          /**< AES cipher with 192-bit NIST KWP mode. */
00184     MBEDTLS_CIPHER_AES_256_KWP,          /**< AES cipher with 256-bit NIST KWP mode. */
00185 } mbedtls_cipher_type_t;
00186 
00187 /** Supported cipher modes. */
00188 typedef enum {
00189     MBEDTLS_MODE_NONE = 0,               /**< None.                        */
00190     MBEDTLS_MODE_ECB,                    /**< The ECB cipher mode.         */
00191     MBEDTLS_MODE_CBC,                    /**< The CBC cipher mode.         */
00192     MBEDTLS_MODE_CFB,                    /**< The CFB cipher mode.         */
00193     MBEDTLS_MODE_OFB,                    /**< The OFB cipher mode.         */
00194     MBEDTLS_MODE_CTR,                    /**< The CTR cipher mode.         */
00195     MBEDTLS_MODE_GCM,                    /**< The GCM cipher mode.         */
00196     MBEDTLS_MODE_STREAM,                 /**< The stream cipher mode.      */
00197     MBEDTLS_MODE_CCM,                    /**< The CCM cipher mode.         */
00198     MBEDTLS_MODE_XTS,                    /**< The XTS cipher mode.         */
00199     MBEDTLS_MODE_CHACHAPOLY,             /**< The ChaCha-Poly cipher mode. */
00200     MBEDTLS_MODE_KW,                     /**< The SP800-38F KW mode */
00201     MBEDTLS_MODE_KWP,                    /**< The SP800-38F KWP mode */
00202 } mbedtls_cipher_mode_t;
00203 
00204 /** Supported cipher padding types. */
00205 typedef enum {
00206     MBEDTLS_PADDING_PKCS7 = 0,     /**< PKCS7 padding (default).        */
00207     MBEDTLS_PADDING_ONE_AND_ZEROS, /**< ISO/IEC 7816-4 padding.         */
00208     MBEDTLS_PADDING_ZEROS_AND_LEN, /**< ANSI X.923 padding.             */
00209     MBEDTLS_PADDING_ZEROS,         /**< Zero padding (not reversible). */
00210     MBEDTLS_PADDING_NONE,          /**< Never pad (full blocks only).   */
00211 } mbedtls_cipher_padding_t;
00212 
00213 /** Type of operation. */
00214 typedef enum {
00215     MBEDTLS_OPERATION_NONE = -1,
00216     MBEDTLS_DECRYPT = 0,
00217     MBEDTLS_ENCRYPT,
00218 } mbedtls_operation_t;
00219 
00220 enum {
00221     /** Undefined key length. */
00222     MBEDTLS_KEY_LENGTH_NONE = 0,
00223     /** Key length, in bits (including parity), for DES keys. */
00224     MBEDTLS_KEY_LENGTH_DES  = 64,
00225     /** Key length in bits, including parity, for DES in two-key EDE. */
00226     MBEDTLS_KEY_LENGTH_DES_EDE = 128,
00227     /** Key length in bits, including parity, for DES in three-key EDE. */
00228     MBEDTLS_KEY_LENGTH_DES_EDE3 = 192,
00229 };
00230 
00231 /** Maximum length of any IV, in Bytes. */
00232 #define MBEDTLS_MAX_IV_LENGTH      16
00233 /** Maximum block size of any cipher, in Bytes. */
00234 #define MBEDTLS_MAX_BLOCK_LENGTH   16
00235 
00236 /**
00237  * Base cipher information (opaque struct).
00238  */
00239 typedef struct mbedtls_cipher_base_t mbedtls_cipher_base_t;
00240 
00241 /**
00242  * CMAC context (opaque struct).
00243  */
00244 typedef struct mbedtls_cmac_context_t mbedtls_cmac_context_t;
00245 
00246 /**
00247  * Cipher information. Allows calling cipher functions
00248  * in a generic way.
00249  */
00250 typedef struct mbedtls_cipher_info_t
00251 {
00252     /** Full cipher identifier. For example,
00253      * MBEDTLS_CIPHER_AES_256_CBC.
00254      */
00255     mbedtls_cipher_type_t type;
00256 
00257     /** The cipher mode. For example, MBEDTLS_MODE_CBC. */
00258     mbedtls_cipher_mode_t mode;
00259 
00260     /** The cipher key length, in bits. This is the
00261      * default length for variable sized ciphers.
00262      * Includes parity bits for ciphers like DES.
00263      */
00264     unsigned int key_bitlen;
00265 
00266     /** Name of the cipher. */
00267     const char * name;
00268 
00269     /** IV or nonce size, in Bytes.
00270      * For ciphers that accept variable IV sizes,
00271      * this is the recommended size.
00272      */
00273     unsigned int iv_size;
00274 
00275     /** Bitflag comprised of MBEDTLS_CIPHER_VARIABLE_IV_LEN and
00276      *  MBEDTLS_CIPHER_VARIABLE_KEY_LEN indicating whether the
00277      *  cipher supports variable IV or variable key sizes, respectively.
00278      */
00279     int flags;
00280 
00281     /** The block size, in Bytes. */
00282     unsigned int block_size;
00283 
00284     /** Struct for base cipher information and functions. */
00285     const mbedtls_cipher_base_t *base;
00286 
00287 } mbedtls_cipher_info_t;
00288 
00289 /**
00290  * Generic cipher context.
00291  */
00292 typedef struct mbedtls_cipher_context_t
00293 {
00294     /** Information about the associated cipher. */
00295     const mbedtls_cipher_info_t *cipher_info;
00296 
00297     /** Key length to use. */
00298     int key_bitlen;
00299 
00300     /** Operation that the key of the context has been
00301      * initialized for.
00302      */
00303     mbedtls_operation_t operation;
00304 
00305 #if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
00306     /** Padding functions to use, if relevant for
00307      * the specific cipher mode.
00308      */
00309     void (*add_padding)( unsigned char *output, size_t olen, size_t data_len );
00310     int (*get_padding)( unsigned char *input, size_t ilen, size_t *data_len );
00311 #endif
00312 
00313     /** Buffer for input that has not been processed yet. */
00314     unsigned char unprocessed_data[MBEDTLS_MAX_BLOCK_LENGTH];
00315 
00316     /** Number of Bytes that have not been processed yet. */
00317     size_t unprocessed_len;
00318 
00319     /** Current IV or NONCE_COUNTER for CTR-mode, data unit (or sector) number
00320      * for XTS-mode. */
00321     unsigned char iv[MBEDTLS_MAX_IV_LENGTH];
00322 
00323     /** IV size in Bytes, for ciphers with variable-length IVs. */
00324     size_t iv_size;
00325 
00326     /** The cipher-specific context. */
00327     void *cipher_ctx;
00328 
00329 #if defined(MBEDTLS_CMAC_C)
00330     /** CMAC-specific context. */
00331     mbedtls_cmac_context_t *cmac_ctx;
00332 #endif
00333 
00334 #if defined(MBEDTLS_USE_PSA_CRYPTO)
00335     /** Indicates whether the cipher operations should be performed
00336      *  by Mbed TLS' own crypto library or an external implementation
00337      *  of the PSA Crypto API.
00338      *  This is unset if the cipher context was established through
00339      *  mbedtls_cipher_setup(), and set if it was established through
00340      *  mbedtls_cipher_setup_psa().
00341      */
00342     unsigned char psa_enabled;
00343 #endif /* MBEDTLS_USE_PSA_CRYPTO */
00344 
00345 } mbedtls_cipher_context_t;
00346 
00347 /**
00348  * \brief This function retrieves the list of ciphers supported
00349  *        by the generic cipher module.
00350  *
00351  *        For any cipher identifier in the returned list, you can
00352  *        obtain the corresponding generic cipher information structure
00353  *        via mbedtls_cipher_info_from_type(), which can then be used
00354  *        to prepare a cipher context via mbedtls_cipher_setup().
00355  *
00356  *
00357  * \return      A statically-allocated array of cipher identifiers
00358  *              of type cipher_type_t. The last entry is zero.
00359  */
00360 const int *mbedtls_cipher_list( void );
00361 
00362 /**
00363  * \brief               This function retrieves the cipher-information
00364  *                      structure associated with the given cipher name.
00365  *
00366  * \param cipher_name   Name of the cipher to search for. This must not be
00367  *                      \c NULL.
00368  *
00369  * \return              The cipher information structure associated with the
00370  *                      given \p cipher_name.
00371  * \return              \c NULL if the associated cipher information is not found.
00372  */
00373 const mbedtls_cipher_info_t *mbedtls_cipher_info_from_string( const char *cipher_name );
00374 
00375 /**
00376  * \brief               This function retrieves the cipher-information
00377  *                      structure associated with the given cipher type.
00378  *
00379  * \param cipher_type   Type of the cipher to search for.
00380  *
00381  * \return              The cipher information structure associated with the
00382  *                      given \p cipher_type.
00383  * \return              \c NULL if the associated cipher information is not found.
00384  */
00385 const mbedtls_cipher_info_t *mbedtls_cipher_info_from_type( const mbedtls_cipher_type_t cipher_type );
00386 
00387 /**
00388  * \brief               This function retrieves the cipher-information
00389  *                      structure associated with the given cipher ID,
00390  *                      key size and mode.
00391  *
00392  * \param cipher_id     The ID of the cipher to search for. For example,
00393  *                      #MBEDTLS_CIPHER_ID_AES.
00394  * \param key_bitlen    The length of the key in bits.
00395  * \param mode          The cipher mode. For example, #MBEDTLS_MODE_CBC.
00396  *
00397  * \return              The cipher information structure associated with the
00398  *                      given \p cipher_id.
00399  * \return              \c NULL if the associated cipher information is not found.
00400  */
00401 const mbedtls_cipher_info_t *mbedtls_cipher_info_from_values( const mbedtls_cipher_id_t cipher_id,
00402                                               int key_bitlen,
00403                                               const mbedtls_cipher_mode_t mode );
00404 
00405 /**
00406  * \brief               This function initializes a \p cipher_context as NONE.
00407  *
00408  * \param ctx           The context to be initialized. This must not be \c NULL.
00409  */
00410 void mbedtls_cipher_init( mbedtls_cipher_context_t *ctx );
00411 
00412 /**
00413  * \brief               This function frees and clears the cipher-specific
00414  *                      context of \p ctx. Freeing \p ctx itself remains the
00415  *                      responsibility of the caller.
00416  *
00417  * \param ctx           The context to be freed. If this is \c NULL, the
00418  *                      function has no effect, otherwise this must point to an
00419  *                      initialized context.
00420  */
00421 void mbedtls_cipher_free( mbedtls_cipher_context_t *ctx );
00422 
00423 
00424 /**
00425  * \brief               This function initializes a cipher context for
00426  *                      use with the given cipher primitive.
00427  *
00428  * \param ctx           The context to initialize. This must be initialized.
00429  * \param cipher_info   The cipher to use.
00430  *
00431  * \return              \c 0 on success.
00432  * \return              #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on
00433  *                      parameter-verification failure.
00434  * \return              #MBEDTLS_ERR_CIPHER_ALLOC_FAILED if allocation of the
00435  *                      cipher-specific context fails.
00436  *
00437  * \internal Currently, the function also clears the structure.
00438  * In future versions, the caller will be required to call
00439  * mbedtls_cipher_init() on the structure first.
00440  */
00441 int mbedtls_cipher_setup( mbedtls_cipher_context_t *ctx,
00442                           const mbedtls_cipher_info_t *cipher_info );
00443 
00444 #if defined(MBEDTLS_USE_PSA_CRYPTO)
00445 /**
00446  * \brief               This function initializes a cipher context for
00447  *                      PSA-based use with the given cipher primitive.
00448  *
00449  * \note                See #MBEDTLS_USE_PSA_CRYPTO for information on PSA.
00450  *
00451  * \param ctx           The context to initialize. May not be \c NULL.
00452  * \param cipher_info   The cipher to use.
00453  * \param taglen        For AEAD ciphers, the length in bytes of the
00454  *                      authentication tag to use. Subsequent uses of
00455  *                      mbedtls_cipher_auth_encrypt() or
00456  *                      mbedtls_cipher_auth_decrypt() must provide
00457  *                      the same tag length.
00458  *                      For non-AEAD ciphers, the value must be \c 0.
00459  *
00460  * \return              \c 0 on success.
00461  * \return              #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on
00462  *                      parameter-verification failure.
00463  * \return              #MBEDTLS_ERR_CIPHER_ALLOC_FAILED if allocation of the
00464  *                      cipher-specific context fails.
00465  */
00466 int mbedtls_cipher_setup_psa( mbedtls_cipher_context_t *ctx,
00467                               const mbedtls_cipher_info_t *cipher_info,
00468                               size_t taglen );
00469 #endif /* MBEDTLS_USE_PSA_CRYPTO */
00470 
00471 /**
00472  * \brief        This function returns the block size of the given cipher.
00473  *
00474  * \param ctx    The context of the cipher. This must be initialized.
00475  *
00476  * \return       The block size of the underlying cipher.
00477  * \return       \c 0 if \p ctx has not been initialized.
00478  */
00479 static inline unsigned int mbedtls_cipher_get_block_size(
00480     const mbedtls_cipher_context_t *ctx )
00481 {
00482     MBEDTLS_INTERNAL_VALIDATE_RET( ctx != NULL, 0 );
00483     if( ctx->cipher_info == NULL )
00484         return 0;
00485 
00486     return ctx->cipher_info->block_size;
00487 }
00488 
00489 /**
00490  * \brief        This function returns the mode of operation for
00491  *               the cipher. For example, MBEDTLS_MODE_CBC.
00492  *
00493  * \param ctx    The context of the cipher. This must be initialized.
00494  *
00495  * \return       The mode of operation.
00496  * \return       #MBEDTLS_MODE_NONE if \p ctx has not been initialized.
00497  */
00498 static inline mbedtls_cipher_mode_t mbedtls_cipher_get_cipher_mode(
00499     const mbedtls_cipher_context_t *ctx )
00500 {
00501     MBEDTLS_INTERNAL_VALIDATE_RET( ctx != NULL, MBEDTLS_MODE_NONE );
00502     if( ctx->cipher_info == NULL )
00503         return MBEDTLS_MODE_NONE;
00504 
00505     return ctx->cipher_info->mode;
00506 }
00507 
00508 /**
00509  * \brief       This function returns the size of the IV or nonce
00510  *              of the cipher, in Bytes.
00511  *
00512  * \param ctx   The context of the cipher. This must be initialized.
00513  *
00514  * \return      The recommended IV size if no IV has been set.
00515  * \return      \c 0 for ciphers not using an IV or a nonce.
00516  * \return      The actual size if an IV has been set.
00517  */
00518 static inline int mbedtls_cipher_get_iv_size(
00519     const mbedtls_cipher_context_t *ctx )
00520 {
00521     MBEDTLS_INTERNAL_VALIDATE_RET( ctx != NULL, 0 );
00522     if( ctx->cipher_info == NULL )
00523         return 0;
00524 
00525     if( ctx->iv_size != 0 )
00526         return (int) ctx->iv_size;
00527 
00528     return (int) ctx->cipher_info->iv_size;
00529 }
00530 
00531 /**
00532  * \brief               This function returns the type of the given cipher.
00533  *
00534  * \param ctx           The context of the cipher. This must be initialized.
00535  *
00536  * \return              The type of the cipher.
00537  * \return              #MBEDTLS_CIPHER_NONE if \p ctx has not been initialized.
00538  */
00539 static inline mbedtls_cipher_type_t mbedtls_cipher_get_type(
00540     const mbedtls_cipher_context_t *ctx )
00541 {
00542     MBEDTLS_INTERNAL_VALIDATE_RET(
00543         ctx != NULL, MBEDTLS_CIPHER_NONE );
00544     if( ctx->cipher_info == NULL )
00545         return MBEDTLS_CIPHER_NONE;
00546 
00547     return ctx->cipher_info->type;
00548 }
00549 
00550 /**
00551  * \brief               This function returns the name of the given cipher
00552  *                      as a string.
00553  *
00554  * \param ctx           The context of the cipher. This must be initialized.
00555  *
00556  * \return              The name of the cipher.
00557  * \return              NULL if \p ctx has not been not initialized.
00558  */
00559 static inline const char *mbedtls_cipher_get_name(
00560     const mbedtls_cipher_context_t *ctx )
00561 {
00562     MBEDTLS_INTERNAL_VALIDATE_RET( ctx != NULL, 0 );
00563     if( ctx->cipher_info == NULL )
00564         return 0;
00565 
00566     return ctx->cipher_info->name;
00567 }
00568 
00569 /**
00570  * \brief               This function returns the key length of the cipher.
00571  *
00572  * \param ctx           The context of the cipher. This must be initialized.
00573  *
00574  * \return              The key length of the cipher in bits.
00575  * \return              #MBEDTLS_KEY_LENGTH_NONE if ctx \p has not been
00576  *                      initialized.
00577  */
00578 static inline int mbedtls_cipher_get_key_bitlen(
00579     const mbedtls_cipher_context_t *ctx )
00580 {
00581     MBEDTLS_INTERNAL_VALIDATE_RET(
00582         ctx != NULL, MBEDTLS_KEY_LENGTH_NONE );
00583     if( ctx->cipher_info == NULL )
00584         return MBEDTLS_KEY_LENGTH_NONE;
00585 
00586     return (int) ctx->cipher_info->key_bitlen;
00587 }
00588 
00589 /**
00590  * \brief          This function returns the operation of the given cipher.
00591  *
00592  * \param ctx      The context of the cipher. This must be initialized.
00593  *
00594  * \return         The type of operation: #MBEDTLS_ENCRYPT or #MBEDTLS_DECRYPT.
00595  * \return         #MBEDTLS_OPERATION_NONE if \p ctx has not been initialized.
00596  */
00597 static inline mbedtls_operation_t mbedtls_cipher_get_operation(
00598     const mbedtls_cipher_context_t *ctx )
00599 {
00600     MBEDTLS_INTERNAL_VALIDATE_RET(
00601         ctx != NULL, MBEDTLS_OPERATION_NONE );
00602     if( ctx->cipher_info == NULL )
00603         return MBEDTLS_OPERATION_NONE;
00604 
00605     return ctx->operation;
00606 }
00607 
00608 /**
00609  * \brief               This function sets the key to use with the given context.
00610  *
00611  * \param ctx           The generic cipher context. This must be initialized and
00612  *                      bound to a cipher information structure.
00613  * \param key           The key to use. This must be a readable buffer of at
00614  *                      least \p key_bitlen Bits.
00615  * \param key_bitlen    The key length to use, in Bits.
00616  * \param operation     The operation that the key will be used for:
00617  *                      #MBEDTLS_ENCRYPT or #MBEDTLS_DECRYPT.
00618  *
00619  * \return              \c 0 on success.
00620  * \return              #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on
00621  *                      parameter-verification failure.
00622  * \return              A cipher-specific error code on failure.
00623  */
00624 int mbedtls_cipher_setkey( mbedtls_cipher_context_t *ctx,
00625                            const unsigned char *key,
00626                            int key_bitlen,
00627                            const mbedtls_operation_t operation );
00628 
00629 #if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
00630 /**
00631  * \brief               This function sets the padding mode, for cipher modes
00632  *                      that use padding.
00633  *
00634  *                      The default passing mode is PKCS7 padding.
00635  *
00636  * \param ctx           The generic cipher context. This must be initialized and
00637  *                      bound to a cipher information structure.
00638  * \param mode          The padding mode.
00639  *
00640  * \return              \c 0 on success.
00641  * \return              #MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE
00642  *                      if the selected padding mode is not supported.
00643  * \return              #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA if the cipher mode
00644  *                      does not support padding.
00645  */
00646 int mbedtls_cipher_set_padding_mode( mbedtls_cipher_context_t *ctx,
00647                                      mbedtls_cipher_padding_t mode );
00648 #endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */
00649 
00650 /**
00651  * \brief           This function sets the initialization vector (IV)
00652  *                  or nonce.
00653  *
00654  * \note            Some ciphers do not use IVs nor nonce. For these
00655  *                  ciphers, this function has no effect.
00656  *
00657  * \param ctx       The generic cipher context. This must be initialized and
00658  *                  bound to a cipher information structure.
00659  * \param iv        The IV to use, or NONCE_COUNTER for CTR-mode ciphers. This
00660  *                  must be a readable buffer of at least \p iv_len Bytes.
00661  * \param iv_len    The IV length for ciphers with variable-size IV.
00662  *                  This parameter is discarded by ciphers with fixed-size IV.
00663  *
00664  * \return          \c 0 on success.
00665  * \return          #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on
00666  *                  parameter-verification failure.
00667  */
00668 int mbedtls_cipher_set_iv( mbedtls_cipher_context_t *ctx,
00669                            const unsigned char *iv,
00670                            size_t iv_len );
00671 
00672 /**
00673  * \brief         This function resets the cipher state.
00674  *
00675  * \param ctx     The generic cipher context. This must be initialized.
00676  *
00677  * \return        \c 0 on success.
00678  * \return        #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on
00679  *                parameter-verification failure.
00680  */
00681 int mbedtls_cipher_reset( mbedtls_cipher_context_t *ctx );
00682 
00683 #if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
00684 /**
00685  * \brief               This function adds additional data for AEAD ciphers.
00686  *                      Currently supported with GCM and ChaCha20+Poly1305.
00687  *                      This must be called exactly once, after
00688  *                      mbedtls_cipher_reset().
00689  *
00690  * \param ctx           The generic cipher context. This must be initialized.
00691  * \param ad            The additional data to use. This must be a readable
00692  *                      buffer of at least \p ad_len Bytes.
00693  * \param ad_len        The length of \p ad in Bytes.
00694  *
00695  * \return              \c 0 on success.
00696  * \return              A specific error code on failure.
00697  */
00698 int mbedtls_cipher_update_ad( mbedtls_cipher_context_t *ctx,
00699                       const unsigned char *ad, size_t ad_len );
00700 #endif /* MBEDTLS_GCM_C || MBEDTLS_CHACHAPOLY_C */
00701 
00702 /**
00703  * \brief               The generic cipher update function. It encrypts or
00704  *                      decrypts using the given cipher context. Writes as
00705  *                      many block-sized blocks of data as possible to output.
00706  *                      Any data that cannot be written immediately is either
00707  *                      added to the next block, or flushed when
00708  *                      mbedtls_cipher_finish() is called.
00709  *                      Exception: For MBEDTLS_MODE_ECB, expects a single block
00710  *                      in size. For example, 16 Bytes for AES.
00711  *
00712  * \note                If the underlying cipher is used in GCM mode, all calls
00713  *                      to this function, except for the last one before
00714  *                      mbedtls_cipher_finish(), must have \p ilen as a
00715  *                      multiple of the block size of the cipher.
00716  *
00717  * \param ctx           The generic cipher context. This must be initialized and
00718  *                      bound to a key.
00719  * \param input         The buffer holding the input data. This must be a
00720  *                      readable buffer of at least \p ilen Bytes.
00721  * \param ilen          The length of the input data.
00722  * \param output        The buffer for the output data. This must be able to
00723  *                      hold at least `ilen + block_size`. This must not be the
00724  *                      same buffer as \p input.
00725  * \param olen          The length of the output data, to be updated with the
00726  *                      actual number of Bytes written. This must not be
00727  *                      \c NULL.
00728  *
00729  * \return              \c 0 on success.
00730  * \return              #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on
00731  *                      parameter-verification failure.
00732  * \return              #MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE on an
00733  *                      unsupported mode for a cipher.
00734  * \return              A cipher-specific error code on failure.
00735  */
00736 int mbedtls_cipher_update( mbedtls_cipher_context_t *ctx,
00737                            const unsigned char *input,
00738                            size_t ilen, unsigned char *output,
00739                            size_t *olen );
00740 
00741 /**
00742  * \brief               The generic cipher finalization function. If data still
00743  *                      needs to be flushed from an incomplete block, the data
00744  *                      contained in it is padded to the size of
00745  *                      the last block, and written to the \p output buffer.
00746  *
00747  * \param ctx           The generic cipher context. This must be initialized and
00748  *                      bound to a key.
00749  * \param output        The buffer to write data to. This needs to be a writable
00750  *                      buffer of at least \p block_size Bytes.
00751  * \param olen          The length of the data written to the \p output buffer.
00752  *                      This may not be \c NULL.
00753  *
00754  * \return              \c 0 on success.
00755  * \return              #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on
00756  *                      parameter-verification failure.
00757  * \return              #MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED on decryption
00758  *                      expecting a full block but not receiving one.
00759  * \return              #MBEDTLS_ERR_CIPHER_INVALID_PADDING on invalid padding
00760  *                      while decrypting.
00761  * \return              A cipher-specific error code on failure.
00762  */
00763 int mbedtls_cipher_finish( mbedtls_cipher_context_t *ctx,
00764                    unsigned char *output, size_t *olen );
00765 
00766 #if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
00767 /**
00768  * \brief               This function writes a tag for AEAD ciphers.
00769  *                      Currently supported with GCM and ChaCha20+Poly1305.
00770  *                      This must be called after mbedtls_cipher_finish().
00771  *
00772  * \param ctx           The generic cipher context. This must be initialized,
00773  *                      bound to a key, and have just completed a cipher
00774  *                      operation through mbedtls_cipher_finish() the tag for
00775  *                      which should be written.
00776  * \param tag           The buffer to write the tag to. This must be a writable
00777  *                      buffer of at least \p tag_len Bytes.
00778  * \param tag_len       The length of the tag to write.
00779  *
00780  * \return              \c 0 on success.
00781  * \return              A specific error code on failure.
00782  */
00783 int mbedtls_cipher_write_tag( mbedtls_cipher_context_t *ctx,
00784                       unsigned char *tag, size_t tag_len );
00785 
00786 /**
00787  * \brief               This function checks the tag for AEAD ciphers.
00788  *                      Currently supported with GCM and ChaCha20+Poly1305.
00789  *                      This must be called after mbedtls_cipher_finish().
00790  *
00791  * \param ctx           The generic cipher context. This must be initialized.
00792  * \param tag           The buffer holding the tag. This must be a readable
00793  *                      buffer of at least \p tag_len Bytes.
00794  * \param tag_len       The length of the tag to check.
00795  *
00796  * \return              \c 0 on success.
00797  * \return              A specific error code on failure.
00798  */
00799 int mbedtls_cipher_check_tag( mbedtls_cipher_context_t *ctx,
00800                       const unsigned char *tag, size_t tag_len );
00801 #endif /* MBEDTLS_GCM_C || MBEDTLS_CHACHAPOLY_C */
00802 
00803 /**
00804  * \brief               The generic all-in-one encryption/decryption function,
00805  *                      for all ciphers except AEAD constructs.
00806  *
00807  * \param ctx           The generic cipher context. This must be initialized.
00808  * \param iv            The IV to use, or NONCE_COUNTER for CTR-mode ciphers.
00809  *                      This must be a readable buffer of at least \p iv_len
00810  *                      Bytes.
00811  * \param iv_len        The IV length for ciphers with variable-size IV.
00812  *                      This parameter is discarded by ciphers with fixed-size
00813  *                      IV.
00814  * \param input         The buffer holding the input data. This must be a
00815  *                      readable buffer of at least \p ilen Bytes.
00816  * \param ilen          The length of the input data in Bytes.
00817  * \param output        The buffer for the output data. This must be able to
00818  *                      hold at least `ilen + block_size`. This must not be the
00819  *                      same buffer as \p input.
00820  * \param olen          The length of the output data, to be updated with the
00821  *                      actual number of Bytes written. This must not be
00822  *                      \c NULL.
00823  *
00824  * \note                Some ciphers do not use IVs nor nonce. For these
00825  *                      ciphers, use \p iv = NULL and \p iv_len = 0.
00826  *
00827  * \return              \c 0 on success.
00828  * \return              #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on
00829  *                      parameter-verification failure.
00830  * \return              #MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED on decryption
00831  *                      expecting a full block but not receiving one.
00832  * \return              #MBEDTLS_ERR_CIPHER_INVALID_PADDING on invalid padding
00833  *                      while decrypting.
00834  * \return              A cipher-specific error code on failure.
00835  */
00836 int mbedtls_cipher_crypt( mbedtls_cipher_context_t *ctx,
00837                   const unsigned char *iv, size_t iv_len,
00838                   const unsigned char *input, size_t ilen,
00839                   unsigned char *output, size_t *olen );
00840 
00841 #if defined(MBEDTLS_CIPHER_MODE_AEAD)
00842 /**
00843  * \brief               The generic autenticated encryption (AEAD) function.
00844  *
00845  * \param ctx           The generic cipher context. This must be initialized and
00846  *                      bound to a key.
00847  * \param iv            The IV to use, or NONCE_COUNTER for CTR-mode ciphers.
00848  *                      This must be a readable buffer of at least \p iv_len
00849  *                      Bytes.
00850  * \param iv_len        The IV length for ciphers with variable-size IV.
00851  *                      This parameter is discarded by ciphers with fixed-size IV.
00852  * \param ad            The additional data to authenticate. This must be a
00853  *                      readable buffer of at least \p ad_len Bytes.
00854  * \param ad_len        The length of \p ad.
00855  * \param input         The buffer holding the input data. This must be a
00856  *                      readable buffer of at least \p ilen Bytes.
00857  * \param ilen          The length of the input data.
00858  * \param output        The buffer for the output data. This must be able to
00859  *                      hold at least \p ilen Bytes.
00860  * \param olen          The length of the output data, to be updated with the
00861  *                      actual number of Bytes written. This must not be
00862  *                      \c NULL.
00863  * \param tag           The buffer for the authentication tag. This must be a
00864  *                      writable buffer of at least \p tag_len Bytes.
00865  * \param tag_len       The desired length of the authentication tag.
00866  *
00867  * \return              \c 0 on success.
00868  * \return              #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on
00869  *                      parameter-verification failure.
00870  * \return              A cipher-specific error code on failure.
00871  */
00872 int mbedtls_cipher_auth_encrypt( mbedtls_cipher_context_t *ctx,
00873                          const unsigned char *iv, size_t iv_len,
00874                          const unsigned char *ad, size_t ad_len,
00875                          const unsigned char *input, size_t ilen,
00876                          unsigned char *output, size_t *olen,
00877                          unsigned char *tag, size_t tag_len );
00878 
00879 /**
00880  * \brief               The generic autenticated decryption (AEAD) function.
00881  *
00882  * \note                If the data is not authentic, then the output buffer
00883  *                      is zeroed out to prevent the unauthentic plaintext being
00884  *                      used, making this interface safer.
00885  *
00886  * \param ctx           The generic cipher context. This must be initialized and
00887  *                      and bound to a key.
00888  * \param iv            The IV to use, or NONCE_COUNTER for CTR-mode ciphers.
00889  *                      This must be a readable buffer of at least \p iv_len
00890  *                      Bytes.
00891  * \param iv_len        The IV length for ciphers with variable-size IV.
00892  *                      This parameter is discarded by ciphers with fixed-size IV.
00893  * \param ad            The additional data to be authenticated. This must be a
00894  *                      readable buffer of at least \p ad_len Bytes.
00895  * \param ad_len        The length of \p ad.
00896  * \param input         The buffer holding the input data. This must be a
00897  *                      readable buffer of at least \p ilen Bytes.
00898  * \param ilen          The length of the input data.
00899  * \param output        The buffer for the output data.
00900  *                      This must be able to hold at least \p ilen Bytes.
00901  * \param olen          The length of the output data, to be updated with the
00902  *                      actual number of Bytes written. This must not be
00903  *                      \c NULL.
00904  * \param tag           The buffer holding the authentication tag. This must be
00905  *                      a readable buffer of at least \p tag_len Bytes.
00906  * \param tag_len       The length of the authentication tag.
00907  *
00908  * \return              \c 0 on success.
00909  * \return              #MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on
00910  *                      parameter-verification failure.
00911  * \return              #MBEDTLS_ERR_CIPHER_AUTH_FAILED if data is not authentic.
00912  * \return              A cipher-specific error code on failure.
00913  */
00914 int mbedtls_cipher_auth_decrypt( mbedtls_cipher_context_t *ctx,
00915                          const unsigned char *iv, size_t iv_len,
00916                          const unsigned char *ad, size_t ad_len,
00917                          const unsigned char *input, size_t ilen,
00918                          unsigned char *output, size_t *olen,
00919                          const unsigned char *tag, size_t tag_len );
00920 #endif /* MBEDTLS_CIPHER_MODE_AEAD */
00921 
00922 #ifdef __cplusplus
00923 }
00924 #endif
00925 
00926 #endif /* MBEDTLS_CIPHER_H */