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/**
* \file cipher.h
*
* \brief Generic cipher wrapper.
*
* \author Adriaan de Jong <dejong@fox-it.com>
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#ifndef MBEDTLS_CIPHER_H
#define MBEDTLS_CIPHER_H
#if !defined(MBEDTLS_CONFIG_FILE)
#include "config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#include <stddef.h>
#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CCM_C)
#define MBEDTLS_CIPHER_MODE_AEAD
#endif
#if defined(MBEDTLS_CIPHER_MODE_CBC)
#define MBEDTLS_CIPHER_MODE_WITH_PADDING
#endif
#if defined(MBEDTLS_ARC4_C)
#define MBEDTLS_CIPHER_MODE_STREAM
#endif
#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && !defined(inline)
#define inline __inline
#endif
#define MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE -0x6080 /**< The selected feature is not available. */
#define MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA -0x6100 /**< Bad input parameters to function. */
#define MBEDTLS_ERR_CIPHER_ALLOC_FAILED -0x6180 /**< Failed to allocate memory. */
#define MBEDTLS_ERR_CIPHER_INVALID_PADDING -0x6200 /**< Input data contains invalid padding and is rejected. */
#define MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED -0x6280 /**< Decryption of block requires a full block. */
#define MBEDTLS_ERR_CIPHER_AUTH_FAILED -0x6300 /**< Authentication failed (for AEAD modes). */
#define MBEDTLS_CIPHER_VARIABLE_IV_LEN 0x01 /**< Cipher accepts IVs of variable length */
#define MBEDTLS_CIPHER_VARIABLE_KEY_LEN 0x02 /**< Cipher accepts keys of variable length */
#ifdef __cplusplus
extern "C" {
#endif
typedef enum {
MBEDTLS_CIPHER_ID_NONE = 0,
MBEDTLS_CIPHER_ID_NULL,
MBEDTLS_CIPHER_ID_AES,
MBEDTLS_CIPHER_ID_DES,
MBEDTLS_CIPHER_ID_3DES,
MBEDTLS_CIPHER_ID_CAMELLIA,
MBEDTLS_CIPHER_ID_BLOWFISH,
MBEDTLS_CIPHER_ID_ARC4,
} mbedtls_cipher_id_t;
typedef enum {
MBEDTLS_CIPHER_NONE = 0,
MBEDTLS_CIPHER_NULL,
MBEDTLS_CIPHER_AES_128_ECB,
MBEDTLS_CIPHER_AES_192_ECB,
MBEDTLS_CIPHER_AES_256_ECB,
MBEDTLS_CIPHER_AES_128_CBC,
MBEDTLS_CIPHER_AES_192_CBC,
MBEDTLS_CIPHER_AES_256_CBC,
MBEDTLS_CIPHER_AES_128_CFB128,
MBEDTLS_CIPHER_AES_192_CFB128,
MBEDTLS_CIPHER_AES_256_CFB128,
MBEDTLS_CIPHER_AES_128_CTR,
MBEDTLS_CIPHER_AES_192_CTR,
MBEDTLS_CIPHER_AES_256_CTR,
MBEDTLS_CIPHER_AES_128_GCM,
MBEDTLS_CIPHER_AES_192_GCM,
MBEDTLS_CIPHER_AES_256_GCM,
MBEDTLS_CIPHER_CAMELLIA_128_ECB,
MBEDTLS_CIPHER_CAMELLIA_192_ECB,
MBEDTLS_CIPHER_CAMELLIA_256_ECB,
MBEDTLS_CIPHER_CAMELLIA_128_CBC,
MBEDTLS_CIPHER_CAMELLIA_192_CBC,
MBEDTLS_CIPHER_CAMELLIA_256_CBC,
MBEDTLS_CIPHER_CAMELLIA_128_CFB128,
MBEDTLS_CIPHER_CAMELLIA_192_CFB128,
MBEDTLS_CIPHER_CAMELLIA_256_CFB128,
MBEDTLS_CIPHER_CAMELLIA_128_CTR,
MBEDTLS_CIPHER_CAMELLIA_192_CTR,
MBEDTLS_CIPHER_CAMELLIA_256_CTR,
MBEDTLS_CIPHER_CAMELLIA_128_GCM,
MBEDTLS_CIPHER_CAMELLIA_192_GCM,
MBEDTLS_CIPHER_CAMELLIA_256_GCM,
MBEDTLS_CIPHER_DES_ECB,
MBEDTLS_CIPHER_DES_CBC,
MBEDTLS_CIPHER_DES_EDE_ECB,
MBEDTLS_CIPHER_DES_EDE_CBC,
MBEDTLS_CIPHER_DES_EDE3_ECB,
MBEDTLS_CIPHER_DES_EDE3_CBC,
MBEDTLS_CIPHER_BLOWFISH_ECB,
MBEDTLS_CIPHER_BLOWFISH_CBC,
MBEDTLS_CIPHER_BLOWFISH_CFB64,
MBEDTLS_CIPHER_BLOWFISH_CTR,
MBEDTLS_CIPHER_ARC4_128,
MBEDTLS_CIPHER_AES_128_CCM,
MBEDTLS_CIPHER_AES_192_CCM,
MBEDTLS_CIPHER_AES_256_CCM,
MBEDTLS_CIPHER_CAMELLIA_128_CCM,
MBEDTLS_CIPHER_CAMELLIA_192_CCM,
MBEDTLS_CIPHER_CAMELLIA_256_CCM,
} mbedtls_cipher_type_t;
typedef enum {
MBEDTLS_MODE_NONE = 0,
MBEDTLS_MODE_ECB,
MBEDTLS_MODE_CBC,
MBEDTLS_MODE_CFB,
MBEDTLS_MODE_OFB, /* Unused! */
MBEDTLS_MODE_CTR,
MBEDTLS_MODE_GCM,
MBEDTLS_MODE_STREAM,
MBEDTLS_MODE_CCM,
} mbedtls_cipher_mode_t;
typedef enum {
MBEDTLS_PADDING_PKCS7 = 0, /**< PKCS7 padding (default) */
MBEDTLS_PADDING_ONE_AND_ZEROS, /**< ISO/IEC 7816-4 padding */
MBEDTLS_PADDING_ZEROS_AND_LEN, /**< ANSI X.923 padding */
MBEDTLS_PADDING_ZEROS, /**< zero padding (not reversible!) */
MBEDTLS_PADDING_NONE, /**< never pad (full blocks only) */
} mbedtls_cipher_padding_t;
typedef enum {
MBEDTLS_OPERATION_NONE = -1,
MBEDTLS_DECRYPT = 0,
MBEDTLS_ENCRYPT,
} mbedtls_operation_t;
enum {
/** Undefined key length */
MBEDTLS_KEY_LENGTH_NONE = 0,
/** Key length, in bits (including parity), for DES keys */
MBEDTLS_KEY_LENGTH_DES = 64,
/** Key length, in bits (including parity), for DES in two key EDE */
MBEDTLS_KEY_LENGTH_DES_EDE = 128,
/** Key length, in bits (including parity), for DES in three-key EDE */
MBEDTLS_KEY_LENGTH_DES_EDE3 = 192,
};
/** Maximum length of any IV, in bytes */
#define MBEDTLS_MAX_IV_LENGTH 16
/** Maximum block size of any cipher, in bytes */
#define MBEDTLS_MAX_BLOCK_LENGTH 16
/**
* Base cipher information (opaque struct).
*/
typedef struct mbedtls_cipher_base_t mbedtls_cipher_base_t;
/**
* Cipher information. Allows cipher functions to be called in a generic way.
*/
typedef struct {
/** Full cipher identifier (e.g. MBEDTLS_CIPHER_AES_256_CBC) */
mbedtls_cipher_type_t type;
/** Cipher mode (e.g. MBEDTLS_MODE_CBC) */
mbedtls_cipher_mode_t mode;
/** Cipher key length, in bits (default length for variable sized ciphers)
* (Includes parity bits for ciphers like DES) */
unsigned int key_bitlen;
/** Name of the cipher */
const char * name;
/** IV/NONCE size, in bytes.
* For cipher that accept many sizes: recommended size */
unsigned int iv_size;
/** Flags for variable IV size, variable key size, etc. */
int flags;
/** block size, in bytes */
unsigned int block_size;
/** Base cipher information and functions */
const mbedtls_cipher_base_t *base;
} mbedtls_cipher_info_t;
/**
* Generic cipher context.
*/
typedef struct {
/** Information about the associated cipher */
const mbedtls_cipher_info_t *cipher_info;
/** Key length to use */
int key_bitlen;
/** Operation that the context's key has been initialised for */
mbedtls_operation_t operation;
#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
/** Padding functions to use, if relevant for cipher mode */
void (*add_padding)( unsigned char *output, size_t olen, size_t data_len );
int (*get_padding)( unsigned char *input, size_t ilen, size_t *data_len );
#endif
/** Buffer for data that hasn't been encrypted yet */
unsigned char unprocessed_data[MBEDTLS_MAX_BLOCK_LENGTH];
/** Number of bytes that still need processing */
size_t unprocessed_len;
/** Current IV or NONCE_COUNTER for CTR-mode */
unsigned char iv[MBEDTLS_MAX_IV_LENGTH];
/** IV size in bytes (for ciphers with variable-length IVs) */
size_t iv_size;
/** Cipher-specific context */
void *cipher_ctx;
} mbedtls_cipher_context_t;
/**
* \brief Returns the list of ciphers supported by the generic cipher module.
*
* \return a statically allocated array of ciphers, the last entry
* is 0.
*/
const int *mbedtls_cipher_list( void );
/**
* \brief Returns the cipher information structure associated
* with the given cipher name.
*
* \param cipher_name Name of the cipher to search for.
*
* \return the cipher information structure associated with the
* given cipher_name, or NULL if not found.
*/
const mbedtls_cipher_info_t *mbedtls_cipher_info_from_string( const char *cipher_name );
/**
* \brief Returns the cipher information structure associated
* with the given cipher type.
*
* \param cipher_type Type of the cipher to search for.
*
* \return the cipher information structure associated with the
* given cipher_type, or NULL if not found.
*/
const mbedtls_cipher_info_t *mbedtls_cipher_info_from_type( const mbedtls_cipher_type_t cipher_type );
/**
* \brief Returns the cipher information structure associated
* with the given cipher id, key size and mode.
*
* \param cipher_id Id of the cipher to search for
* (e.g. MBEDTLS_CIPHER_ID_AES)
* \param key_bitlen Length of the key in bits
* \param mode Cipher mode (e.g. MBEDTLS_MODE_CBC)
*
* \return the cipher information structure associated with the
* given cipher_type, or NULL if not found.
*/
const mbedtls_cipher_info_t *mbedtls_cipher_info_from_values( const mbedtls_cipher_id_t cipher_id,
int key_bitlen,
const mbedtls_cipher_mode_t mode );
/**
* \brief Initialize a cipher_context (as NONE)
*/
void mbedtls_cipher_init( mbedtls_cipher_context_t *ctx );
/**
* \brief Free and clear the cipher-specific context of ctx.
* Freeing ctx itself remains the responsibility of the
* caller.
*/
void mbedtls_cipher_free( mbedtls_cipher_context_t *ctx );
/**
* \brief Initialises and fills the cipher context structure with
* the appropriate values.
*
* \note Currently also clears structure. In future versions you
* will be required to call mbedtls_cipher_init() on the structure
* first.
*
* \param ctx context to initialise. May not be NULL.
* \param cipher_info cipher to use.
*
* \return 0 on success,
* MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on parameter failure,
* MBEDTLS_ERR_CIPHER_ALLOC_FAILED if allocation of the
* cipher-specific context failed.
*/
int mbedtls_cipher_setup( mbedtls_cipher_context_t *ctx, const mbedtls_cipher_info_t *cipher_info );
/**
* \brief Returns the block size of the given cipher.
*
* \param ctx cipher's context. Must have been initialised.
*
* \return size of the cipher's blocks, or 0 if ctx has not been
* initialised.
*/
static inline unsigned int mbedtls_cipher_get_block_size( const mbedtls_cipher_context_t *ctx )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return 0;
return ctx->cipher_info->block_size;
}
/**
* \brief Returns the mode of operation for the cipher.
* (e.g. MBEDTLS_MODE_CBC)
*
* \param ctx cipher's context. Must have been initialised.
*
* \return mode of operation, or MBEDTLS_MODE_NONE if ctx
* has not been initialised.
*/
static inline mbedtls_cipher_mode_t mbedtls_cipher_get_cipher_mode( const mbedtls_cipher_context_t *ctx )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return MBEDTLS_MODE_NONE;
return ctx->cipher_info->mode;
}
/**
* \brief Returns the size of the cipher's IV/NONCE in bytes.
*
* \param ctx cipher's context. Must have been initialised.
*
* \return If IV has not been set yet: (recommended) IV size
* (0 for ciphers not using IV/NONCE).
* If IV has already been set: actual size.
*/
static inline int mbedtls_cipher_get_iv_size( const mbedtls_cipher_context_t *ctx )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return 0;
if( ctx->iv_size != 0 )
return (int) ctx->iv_size;
return (int) ctx->cipher_info->iv_size;
}
/**
* \brief Returns the type of the given cipher.
*
* \param ctx cipher's context. Must have been initialised.
*
* \return type of the cipher, or MBEDTLS_CIPHER_NONE if ctx has
* not been initialised.
*/
static inline mbedtls_cipher_type_t mbedtls_cipher_get_type( const mbedtls_cipher_context_t *ctx )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return MBEDTLS_CIPHER_NONE;
return ctx->cipher_info->type;
}
/**
* \brief Returns the name of the given cipher, as a string.
*
* \param ctx cipher's context. Must have been initialised.
*
* \return name of the cipher, or NULL if ctx was not initialised.
*/
static inline const char *mbedtls_cipher_get_name( const mbedtls_cipher_context_t *ctx )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return 0;
return ctx->cipher_info->name;
}
/**
* \brief Returns the key length of the cipher.
*
* \param ctx cipher's context. Must have been initialised.
*
* \return cipher's key length, in bits, or
* MBEDTLS_KEY_LENGTH_NONE if ctx has not been
* initialised.
*/
static inline int mbedtls_cipher_get_key_bitlen( const mbedtls_cipher_context_t *ctx )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return MBEDTLS_KEY_LENGTH_NONE;
return (int) ctx->cipher_info->key_bitlen;
}
/**
* \brief Returns the operation of the given cipher.
*
* \param ctx cipher's context. Must have been initialised.
*
* \return operation (MBEDTLS_ENCRYPT or MBEDTLS_DECRYPT),
* or MBEDTLS_OPERATION_NONE if ctx has not been
* initialised.
*/
static inline mbedtls_operation_t mbedtls_cipher_get_operation( const mbedtls_cipher_context_t *ctx )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return MBEDTLS_OPERATION_NONE;
return ctx->operation;
}
/**
* \brief Set the key to use with the given context.
*
* \param ctx generic cipher context. May not be NULL. Must have been
* initialised using cipher_context_from_type or
* cipher_context_from_string.
* \param key The key to use.
* \param key_bitlen key length to use, in bits.
* \param operation Operation that the key will be used for, either
* MBEDTLS_ENCRYPT or MBEDTLS_DECRYPT.
*
* \returns 0 on success, MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA if
* parameter verification fails or a cipher specific
* error code.
*/
int mbedtls_cipher_setkey( mbedtls_cipher_context_t *ctx, const unsigned char *key,
int key_bitlen, const mbedtls_operation_t operation );
#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
/**
* \brief Set padding mode, for cipher modes that use padding.
* (Default: PKCS7 padding.)
*
* \param ctx generic cipher context
* \param mode padding mode
*
* \returns 0 on success, MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE
* if selected padding mode is not supported, or
* MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA if the cipher mode
* does not support padding.
*/
int mbedtls_cipher_set_padding_mode( mbedtls_cipher_context_t *ctx, mbedtls_cipher_padding_t mode );
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */
/**
* \brief Set the initialization vector (IV) or nonce
*
* \param ctx generic cipher context
* \param iv IV to use (or NONCE_COUNTER for CTR-mode ciphers)
* \param iv_len IV length for ciphers with variable-size IV;
* discarded by ciphers with fixed-size IV.
*
* \returns 0 on success, or MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA
*
* \note Some ciphers don't use IVs nor NONCE. For these
* ciphers, this function has no effect.
*/
int mbedtls_cipher_set_iv( mbedtls_cipher_context_t *ctx,
const unsigned char *iv, size_t iv_len );
/**
* \brief Finish preparation of the given context
*
* \param ctx generic cipher context
*
* \returns 0 on success, MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA
* if parameter verification fails.
*/
int mbedtls_cipher_reset( mbedtls_cipher_context_t *ctx );
#if defined(MBEDTLS_GCM_C)
/**
* \brief Add additional data (for AEAD ciphers).
* Currently only supported with GCM.
* Must be called exactly once, after mbedtls_cipher_reset().
*
* \param ctx generic cipher context
* \param ad Additional data to use.
* \param ad_len Length of ad.
*
* \return 0 on success, or a specific error code.
*/
int mbedtls_cipher_update_ad( mbedtls_cipher_context_t *ctx,
const unsigned char *ad, size_t ad_len );
#endif /* MBEDTLS_GCM_C */
/**
* \brief Generic cipher update function. Encrypts/decrypts
* using the given cipher context. Writes as many block
* size'd blocks of data as possible to output. Any data
* that cannot be written immediately will either be added
* to the next block, or flushed when cipher_final is
* called.
* Exception: for MBEDTLS_MODE_ECB, expects single block
* in size (e.g. 16 bytes for AES)
*
* \param ctx generic cipher context
* \param input buffer holding the input data
* \param ilen length of the input data
* \param output buffer for the output data. Should be able to hold at
* least ilen + block_size. Cannot be the same buffer as
* input!
* \param olen length of the output data, will be filled with the
* actual number of bytes written.
*
* \returns 0 on success, MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA if
* parameter verification fails,
* MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE on an
* unsupported mode for a cipher or a cipher specific
* error code.
*
* \note If the underlying cipher is GCM, all calls to this
* function, except the last one before mbedtls_cipher_finish(),
* must have ilen a multiple of the block size.
*/
int mbedtls_cipher_update( mbedtls_cipher_context_t *ctx, const unsigned char *input,
size_t ilen, unsigned char *output, size_t *olen );
/**
* \brief Generic cipher finalisation function. If data still
* needs to be flushed from an incomplete block, data
* contained within it will be padded with the size of
* the last block, and written to the output buffer.
*
* \param ctx Generic cipher context
* \param output buffer to write data to. Needs block_size available.
* \param olen length of the data written to the output buffer.
*
* \returns 0 on success, MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA if
* parameter verification fails,
* MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED if decryption
* expected a full block but was not provided one,
* MBEDTLS_ERR_CIPHER_INVALID_PADDING on invalid padding
* while decrypting or a cipher specific error code.
*/
int mbedtls_cipher_finish( mbedtls_cipher_context_t *ctx,
unsigned char *output, size_t *olen );
#if defined(MBEDTLS_GCM_C)
/**
* \brief Write tag for AEAD ciphers.
* Currently only supported with GCM.
* Must be called after mbedtls_cipher_finish().
*
* \param ctx Generic cipher context
* \param tag buffer to write the tag
* \param tag_len Length of the tag to write
*
* \return 0 on success, or a specific error code.
*/
int mbedtls_cipher_write_tag( mbedtls_cipher_context_t *ctx,
unsigned char *tag, size_t tag_len );
/**
* \brief Check tag for AEAD ciphers.
* Currently only supported with GCM.
* Must be called after mbedtls_cipher_finish().
*
* \param ctx Generic cipher context
* \param tag Buffer holding the tag
* \param tag_len Length of the tag to check
*
* \return 0 on success, or a specific error code.
*/
int mbedtls_cipher_check_tag( mbedtls_cipher_context_t *ctx,
const unsigned char *tag, size_t tag_len );
#endif /* MBEDTLS_GCM_C */
/**
* \brief Generic all-in-one encryption/decryption
* (for all ciphers except AEAD constructs).
*
* \param ctx generic cipher context
* \param iv IV to use (or NONCE_COUNTER for CTR-mode ciphers)
* \param iv_len IV length for ciphers with variable-size IV;
* discarded by ciphers with fixed-size IV.
* \param input buffer holding the input data
* \param ilen length of the input data
* \param output buffer for the output data. Should be able to hold at
* least ilen + block_size. Cannot be the same buffer as
* input!
* \param olen length of the output data, will be filled with the
* actual number of bytes written.
*
* \note Some ciphers don't use IVs nor NONCE. For these
* ciphers, use iv = NULL and iv_len = 0.
*
* \returns 0 on success, or
* MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA, or
* MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED if decryption
* expected a full block but was not provided one, or
* MBEDTLS_ERR_CIPHER_INVALID_PADDING on invalid padding
* while decrypting, or
* a cipher specific error code.
*/
int mbedtls_cipher_crypt( mbedtls_cipher_context_t *ctx,
const unsigned char *iv, size_t iv_len,
const unsigned char *input, size_t ilen,
unsigned char *output, size_t *olen );
#if defined(MBEDTLS_CIPHER_MODE_AEAD)
/**
* \brief Generic autenticated encryption (AEAD ciphers).
*
* \param ctx generic cipher context
* \param iv IV to use (or NONCE_COUNTER for CTR-mode ciphers)
* \param iv_len IV length for ciphers with variable-size IV;
* discarded by ciphers with fixed-size IV.
* \param ad Additional data to authenticate.
* \param ad_len Length of ad.
* \param input buffer holding the input data
* \param ilen length of the input data
* \param output buffer for the output data.
* Should be able to hold at least ilen.
* \param olen length of the output data, will be filled with the
* actual number of bytes written.
* \param tag buffer for the authentication tag
* \param tag_len desired tag length
*
* \returns 0 on success, or
* MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA, or
* a cipher specific error code.
*/
int mbedtls_cipher_auth_encrypt( mbedtls_cipher_context_t *ctx,
const unsigned char *iv, size_t iv_len,
const unsigned char *ad, size_t ad_len,
const unsigned char *input, size_t ilen,
unsigned char *output, size_t *olen,
unsigned char *tag, size_t tag_len );
/**
* \brief Generic autenticated decryption (AEAD ciphers).
*
* \param ctx generic cipher context
* \param iv IV to use (or NONCE_COUNTER for CTR-mode ciphers)
* \param iv_len IV length for ciphers with variable-size IV;
* discarded by ciphers with fixed-size IV.
* \param ad Additional data to be authenticated.
* \param ad_len Length of ad.
* \param input buffer holding the input data
* \param ilen length of the input data
* \param output buffer for the output data.
* Should be able to hold at least ilen.
* \param olen length of the output data, will be filled with the
* actual number of bytes written.
* \param tag buffer holding the authentication tag
* \param tag_len length of the authentication tag
*
* \returns 0 on success, or
* MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA, or
* MBEDTLS_ERR_CIPHER_AUTH_FAILED if data isn't authentic,
* or a cipher specific error code.
*
* \note If the data is not authentic, then the output buffer
* is zeroed out to prevent the unauthentic plaintext to
* be used by mistake, making this interface safer.
*/
int mbedtls_cipher_auth_decrypt( mbedtls_cipher_context_t *ctx,
const unsigned char *iv, size_t iv_len,
const unsigned char *ad, size_t ad_len,
const unsigned char *input, size_t ilen,
unsigned char *output, size_t *olen,
const unsigned char *tag, size_t tag_len );
#endif /* MBEDTLS_CIPHER_MODE_AEAD */
#ifdef __cplusplus
}
#endif
#endif /* MBEDTLS_CIPHER_H */