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mbedtls/library/cipher.c
Simon Butcher 0c79073a8b Refactor and change CMAC interface 
Change the CMAC interface to match the mbedtls_md_hmac_xxxx() interface. This
changes the overall design of the CMAC interface to make it more consistent with
the existing HMAC interface, and will allow incremental updates of input data
rather than requiring all data to be presented at once, which is what the
current interface requires.
2016-10-13 13:51:11 +01:00

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26 KiB
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/**
* \file cipher.c
*
* \brief Generic cipher wrapper for mbed TLS
*
* \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)
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_CIPHER_C)
#include "mbedtls/cipher.h"
#include "mbedtls/cipher_internal.h"
#include <stdlib.h>
#include <string.h>
#if defined(MBEDTLS_GCM_C)
#include "mbedtls/gcm.h"
#endif
#if defined(MBEDTLS_CCM_C)
#include "mbedtls/ccm.h"
#endif
#if defined(MBEDTLS_CMAC_C)
#include "mbedtls/cmac.h"
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif
#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER)
#define MBEDTLS_CIPHER_MODE_STREAM
#endif
/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize( void *v, size_t n ) {
volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0;
}
static int supported_init = 0;
const int *mbedtls_cipher_list( void )
{
const mbedtls_cipher_definition_t *def;
int *type;
if( ! supported_init )
{
def = mbedtls_cipher_definitions;
type = mbedtls_cipher_supported;
while( def->type != 0 )
*type++ = (*def++).type;
*type = 0;
supported_init = 1;
}
return( mbedtls_cipher_supported );
}
const mbedtls_cipher_info_t *mbedtls_cipher_info_from_type( const mbedtls_cipher_type_t cipher_type )
{
const mbedtls_cipher_definition_t *def;
for( def = mbedtls_cipher_definitions; def->info != NULL; def++ )
if( def->type == cipher_type )
return( def->info );
return( NULL );
}
const mbedtls_cipher_info_t *mbedtls_cipher_info_from_string( const char *cipher_name )
{
const mbedtls_cipher_definition_t *def;
if( NULL == cipher_name )
return( NULL );
for( def = mbedtls_cipher_definitions; def->info != NULL; def++ )
if( ! strcmp( def->info->name, cipher_name ) )
return( def->info );
return( NULL );
}
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 )
{
const mbedtls_cipher_definition_t *def;
for( def = mbedtls_cipher_definitions; def->info != NULL; def++ )
if( def->info->base->cipher == cipher_id &&
def->info->key_bitlen == (unsigned) key_bitlen &&
def->info->mode == mode )
return( def->info );
return( NULL );
}
void mbedtls_cipher_init( mbedtls_cipher_context_t *ctx )
{
memset( ctx, 0, sizeof( mbedtls_cipher_context_t ) );
}
void mbedtls_cipher_free( mbedtls_cipher_context_t *ctx )
{
if( ctx == NULL )
return;
#if defined(MBEDTLS_CMAC_C)
if( ctx->cmac_ctx )
{
mbedtls_zeroize( ctx->cmac_ctx, sizeof( mbedtls_cmac_context_t ) );
mbedtls_free( ctx->cmac_ctx );
}
#endif
if( ctx->cipher_ctx )
ctx->cipher_info->base->ctx_free_func( ctx->cipher_ctx );
mbedtls_zeroize( ctx, sizeof(mbedtls_cipher_context_t) );
}
int mbedtls_cipher_setup( mbedtls_cipher_context_t *ctx, const mbedtls_cipher_info_t *cipher_info )
{
if( NULL == cipher_info || NULL == ctx )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
memset( ctx, 0, sizeof( mbedtls_cipher_context_t ) );
if( NULL == ( ctx->cipher_ctx = cipher_info->base->ctx_alloc_func() ) )
return( MBEDTLS_ERR_CIPHER_ALLOC_FAILED );
ctx->cipher_info = cipher_info;
#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
/*
* Ignore possible errors caused by a cipher mode that doesn't use padding
*/
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
(void) mbedtls_cipher_set_padding_mode( ctx, MBEDTLS_PADDING_PKCS7 );
#else
(void) mbedtls_cipher_set_padding_mode( ctx, MBEDTLS_PADDING_NONE );
#endif
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */
return( 0 );
}
int mbedtls_cipher_setkey( mbedtls_cipher_context_t *ctx, const unsigned char *key,
int key_bitlen, const mbedtls_operation_t operation )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
if( ( ctx->cipher_info->flags & MBEDTLS_CIPHER_VARIABLE_KEY_LEN ) == 0 &&
(int) ctx->cipher_info->key_bitlen != key_bitlen )
{
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
}
ctx->key_bitlen = key_bitlen;
ctx->operation = operation;
/*
* For CFB and CTR mode always use the encryption key schedule
*/
if( MBEDTLS_ENCRYPT == operation ||
MBEDTLS_MODE_CFB == ctx->cipher_info->mode ||
MBEDTLS_MODE_CTR == ctx->cipher_info->mode )
{
return ctx->cipher_info->base->setkey_enc_func( ctx->cipher_ctx, key,
ctx->key_bitlen );
}
if( MBEDTLS_DECRYPT == operation )
return ctx->cipher_info->base->setkey_dec_func( ctx->cipher_ctx, key,
ctx->key_bitlen );
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
}
int mbedtls_cipher_set_iv( mbedtls_cipher_context_t *ctx,
const unsigned char *iv, size_t iv_len )
{
size_t actual_iv_size;
if( NULL == ctx || NULL == ctx->cipher_info || NULL == iv )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
/* avoid buffer overflow in ctx->iv */
if( iv_len > MBEDTLS_MAX_IV_LENGTH )
return( MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE );
if( ( ctx->cipher_info->flags & MBEDTLS_CIPHER_VARIABLE_IV_LEN ) != 0 )
actual_iv_size = iv_len;
else
{
actual_iv_size = ctx->cipher_info->iv_size;
/* avoid reading past the end of input buffer */
if( actual_iv_size > iv_len )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
}
memcpy( ctx->iv, iv, actual_iv_size );
ctx->iv_size = actual_iv_size;
return( 0 );
}
int mbedtls_cipher_reset( mbedtls_cipher_context_t *ctx )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
ctx->unprocessed_len = 0;
return( 0 );
}
#if defined(MBEDTLS_GCM_C)
int mbedtls_cipher_update_ad( mbedtls_cipher_context_t *ctx,
const unsigned char *ad, size_t ad_len )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
if( MBEDTLS_MODE_GCM == ctx->cipher_info->mode )
{
return mbedtls_gcm_starts( (mbedtls_gcm_context *) ctx->cipher_ctx, ctx->operation,
ctx->iv, ctx->iv_size, ad, ad_len );
}
return( 0 );
}
#endif /* MBEDTLS_GCM_C */
int mbedtls_cipher_update( mbedtls_cipher_context_t *ctx, const unsigned char *input,
size_t ilen, unsigned char *output, size_t *olen )
{
int ret;
size_t block_size = 0;
if( NULL == ctx || NULL == ctx->cipher_info || NULL == olen )
{
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
}
*olen = 0;
block_size = mbedtls_cipher_get_block_size( ctx );
if( ctx->cipher_info->mode == MBEDTLS_MODE_ECB )
{
if( ilen != block_size )
return( MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED );
*olen = ilen;
if( 0 != ( ret = ctx->cipher_info->base->ecb_func( ctx->cipher_ctx,
ctx->operation, input, output ) ) )
{
return( ret );
}
return( 0 );
}
#if defined(MBEDTLS_GCM_C)
if( ctx->cipher_info->mode == MBEDTLS_MODE_GCM )
{
*olen = ilen;
return mbedtls_gcm_update( (mbedtls_gcm_context *) ctx->cipher_ctx, ilen, input,
output );
}
#endif
if ( 0 == block_size )
{
return MBEDTLS_ERR_CIPHER_INVALID_CONTEXT;
}
if( input == output &&
( ctx->unprocessed_len != 0 || ilen % block_size ) )
{
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
}
#if defined(MBEDTLS_CIPHER_MODE_CBC)
if( ctx->cipher_info->mode == MBEDTLS_MODE_CBC )
{
size_t copy_len = 0;
/*
* If there is not enough data for a full block, cache it.
*/
if( ( ctx->operation == MBEDTLS_DECRYPT &&
ilen + ctx->unprocessed_len <= block_size ) ||
( ctx->operation == MBEDTLS_ENCRYPT &&
ilen + ctx->unprocessed_len < block_size ) )
{
memcpy( &( ctx->unprocessed_data[ctx->unprocessed_len] ), input,
ilen );
ctx->unprocessed_len += ilen;
return( 0 );
}
/*
* Process cached data first
*/
if( 0 != ctx->unprocessed_len )
{
copy_len = block_size - ctx->unprocessed_len;
memcpy( &( ctx->unprocessed_data[ctx->unprocessed_len] ), input,
copy_len );
if( 0 != ( ret = ctx->cipher_info->base->cbc_func( ctx->cipher_ctx,
ctx->operation, block_size, ctx->iv,
ctx->unprocessed_data, output ) ) )
{
return( ret );
}
*olen += block_size;
output += block_size;
ctx->unprocessed_len = 0;
input += copy_len;
ilen -= copy_len;
}
/*
* Cache final, incomplete block
*/
if( 0 != ilen )
{
if( 0 == block_size )
{
return MBEDTLS_ERR_CIPHER_INVALID_CONTEXT;
}
copy_len = ilen % block_size;
if( copy_len == 0 && ctx->operation == MBEDTLS_DECRYPT )
copy_len = block_size;
memcpy( ctx->unprocessed_data, &( input[ilen - copy_len] ),
copy_len );
ctx->unprocessed_len += copy_len;
ilen -= copy_len;
}
/*
* Process remaining full blocks
*/
if( ilen )
{
if( 0 != ( ret = ctx->cipher_info->base->cbc_func( ctx->cipher_ctx,
ctx->operation, ilen, ctx->iv, input, output ) ) )
{
return( ret );
}
*olen += ilen;
}
return( 0 );
}
#endif /* MBEDTLS_CIPHER_MODE_CBC */
#if defined(MBEDTLS_CIPHER_MODE_CFB)
if( ctx->cipher_info->mode == MBEDTLS_MODE_CFB )
{
if( 0 != ( ret = ctx->cipher_info->base->cfb_func( ctx->cipher_ctx,
ctx->operation, ilen, &ctx->unprocessed_len, ctx->iv,
input, output ) ) )
{
return( ret );
}
*olen = ilen;
return( 0 );
}
#endif /* MBEDTLS_CIPHER_MODE_CFB */
#if defined(MBEDTLS_CIPHER_MODE_CTR)
if( ctx->cipher_info->mode == MBEDTLS_MODE_CTR )
{
if( 0 != ( ret = ctx->cipher_info->base->ctr_func( ctx->cipher_ctx,
ilen, &ctx->unprocessed_len, ctx->iv,
ctx->unprocessed_data, input, output ) ) )
{
return( ret );
}
*olen = ilen;
return( 0 );
}
#endif /* MBEDTLS_CIPHER_MODE_CTR */
#if defined(MBEDTLS_CIPHER_MODE_STREAM)
if( ctx->cipher_info->mode == MBEDTLS_MODE_STREAM )
{
if( 0 != ( ret = ctx->cipher_info->base->stream_func( ctx->cipher_ctx,
ilen, input, output ) ) )
{
return( ret );
}
*olen = ilen;
return( 0 );
}
#endif /* MBEDTLS_CIPHER_MODE_STREAM */
return( MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE );
}
#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
/*
* PKCS7 (and PKCS5) padding: fill with ll bytes, with ll = padding_len
*/
static void add_pkcs_padding( unsigned char *output, size_t output_len,
size_t data_len )
{
size_t padding_len = output_len - data_len;
unsigned char i;
for( i = 0; i < padding_len; i++ )
output[data_len + i] = (unsigned char) padding_len;
}
static int get_pkcs_padding( unsigned char *input, size_t input_len,
size_t *data_len )
{
size_t i, pad_idx;
unsigned char padding_len, bad = 0;
if( NULL == input || NULL == data_len )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
padding_len = input[input_len - 1];
*data_len = input_len - padding_len;
/* Avoid logical || since it results in a branch */
bad |= padding_len > input_len;
bad |= padding_len == 0;
/* The number of bytes checked must be independent of padding_len,
* so pick input_len, which is usually 8 or 16 (one block) */
pad_idx = input_len - padding_len;
for( i = 0; i < input_len; i++ )
bad |= ( input[i] ^ padding_len ) * ( i >= pad_idx );
return( MBEDTLS_ERR_CIPHER_INVALID_PADDING * ( bad != 0 ) );
}
#endif /* MBEDTLS_CIPHER_PADDING_PKCS7 */
#if defined(MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS)
/*
* One and zeros padding: fill with 80 00 ... 00
*/
static void add_one_and_zeros_padding( unsigned char *output,
size_t output_len, size_t data_len )
{
size_t padding_len = output_len - data_len;
unsigned char i = 0;
output[data_len] = 0x80;
for( i = 1; i < padding_len; i++ )
output[data_len + i] = 0x00;
}
static int get_one_and_zeros_padding( unsigned char *input, size_t input_len,
size_t *data_len )
{
size_t i;
unsigned char done = 0, prev_done, bad;
if( NULL == input || NULL == data_len )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
bad = 0xFF;
*data_len = 0;
for( i = input_len; i > 0; i-- )
{
prev_done = done;
done |= ( input[i-1] != 0 );
*data_len |= ( i - 1 ) * ( done != prev_done );
bad &= ( input[i-1] ^ 0x80 ) | ( done == prev_done );
}
return( MBEDTLS_ERR_CIPHER_INVALID_PADDING * ( bad != 0 ) );
}
#endif /* MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS */
#if defined(MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN)
/*
* Zeros and len padding: fill with 00 ... 00 ll, where ll is padding length
*/
static void add_zeros_and_len_padding( unsigned char *output,
size_t output_len, size_t data_len )
{
size_t padding_len = output_len - data_len;
unsigned char i = 0;
for( i = 1; i < padding_len; i++ )
output[data_len + i - 1] = 0x00;
output[output_len - 1] = (unsigned char) padding_len;
}
static int get_zeros_and_len_padding( unsigned char *input, size_t input_len,
size_t *data_len )
{
size_t i, pad_idx;
unsigned char padding_len, bad = 0;
if( NULL == input || NULL == data_len )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
padding_len = input[input_len - 1];
*data_len = input_len - padding_len;
/* Avoid logical || since it results in a branch */
bad |= padding_len > input_len;
bad |= padding_len == 0;
/* The number of bytes checked must be independent of padding_len */
pad_idx = input_len - padding_len;
for( i = 0; i < input_len - 1; i++ )
bad |= input[i] * ( i >= pad_idx );
return( MBEDTLS_ERR_CIPHER_INVALID_PADDING * ( bad != 0 ) );
}
#endif /* MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN */
#if defined(MBEDTLS_CIPHER_PADDING_ZEROS)
/*
* Zero padding: fill with 00 ... 00
*/
static void add_zeros_padding( unsigned char *output,
size_t output_len, size_t data_len )
{
size_t i;
for( i = data_len; i < output_len; i++ )
output[i] = 0x00;
}
static int get_zeros_padding( unsigned char *input, size_t input_len,
size_t *data_len )
{
size_t i;
unsigned char done = 0, prev_done;
if( NULL == input || NULL == data_len )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
*data_len = 0;
for( i = input_len; i > 0; i-- )
{
prev_done = done;
done |= ( input[i-1] != 0 );
*data_len |= i * ( done != prev_done );
}
return( 0 );
}
#endif /* MBEDTLS_CIPHER_PADDING_ZEROS */
/*
* No padding: don't pad :)
*
* There is no add_padding function (check for NULL in mbedtls_cipher_finish)
* but a trivial get_padding function
*/
static int get_no_padding( unsigned char *input, size_t input_len,
size_t *data_len )
{
if( NULL == input || NULL == data_len )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
*data_len = input_len;
return( 0 );
}
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */
int mbedtls_cipher_finish( mbedtls_cipher_context_t *ctx,
unsigned char *output, size_t *olen )
{
if( NULL == ctx || NULL == ctx->cipher_info || NULL == olen )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
*olen = 0;
if( MBEDTLS_MODE_CFB == ctx->cipher_info->mode ||
MBEDTLS_MODE_CTR == ctx->cipher_info->mode ||
MBEDTLS_MODE_GCM == ctx->cipher_info->mode ||
MBEDTLS_MODE_STREAM == ctx->cipher_info->mode )
{
return( 0 );
}
if( MBEDTLS_MODE_ECB == ctx->cipher_info->mode )
{
if( ctx->unprocessed_len != 0 )
return( MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED );
return( 0 );
}
#if defined(MBEDTLS_CIPHER_MODE_CBC)
if( MBEDTLS_MODE_CBC == ctx->cipher_info->mode )
{
int ret = 0;
if( MBEDTLS_ENCRYPT == ctx->operation )
{
/* check for 'no padding' mode */
if( NULL == ctx->add_padding )
{
if( 0 != ctx->unprocessed_len )
return( MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED );
return( 0 );
}
ctx->add_padding( ctx->unprocessed_data, mbedtls_cipher_get_iv_size( ctx ),
ctx->unprocessed_len );
}
else if( mbedtls_cipher_get_block_size( ctx ) != ctx->unprocessed_len )
{
/*
* For decrypt operations, expect a full block,
* or an empty block if no padding
*/
if( NULL == ctx->add_padding && 0 == ctx->unprocessed_len )
return( 0 );
return( MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED );
}
/* cipher block */
if( 0 != ( ret = ctx->cipher_info->base->cbc_func( ctx->cipher_ctx,
ctx->operation, mbedtls_cipher_get_block_size( ctx ), ctx->iv,
ctx->unprocessed_data, output ) ) )
{
return( ret );
}
/* Set output size for decryption */
if( MBEDTLS_DECRYPT == ctx->operation )
return ctx->get_padding( output, mbedtls_cipher_get_block_size( ctx ),
olen );
/* Set output size for encryption */
*olen = mbedtls_cipher_get_block_size( ctx );
return( 0 );
}
#else
((void) output);
#endif /* MBEDTLS_CIPHER_MODE_CBC */
return( MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE );
}
#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
int mbedtls_cipher_set_padding_mode( mbedtls_cipher_context_t *ctx, mbedtls_cipher_padding_t mode )
{
if( NULL == ctx ||
MBEDTLS_MODE_CBC != ctx->cipher_info->mode )
{
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
}
switch( mode )
{
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
case MBEDTLS_PADDING_PKCS7:
ctx->add_padding = add_pkcs_padding;
ctx->get_padding = get_pkcs_padding;
break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS)
case MBEDTLS_PADDING_ONE_AND_ZEROS:
ctx->add_padding = add_one_and_zeros_padding;
ctx->get_padding = get_one_and_zeros_padding;
break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN)
case MBEDTLS_PADDING_ZEROS_AND_LEN:
ctx->add_padding = add_zeros_and_len_padding;
ctx->get_padding = get_zeros_and_len_padding;
break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ZEROS)
case MBEDTLS_PADDING_ZEROS:
ctx->add_padding = add_zeros_padding;
ctx->get_padding = get_zeros_padding;
break;
#endif
case MBEDTLS_PADDING_NONE:
ctx->add_padding = NULL;
ctx->get_padding = get_no_padding;
break;
default:
return( MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE );
}
return( 0 );
}
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */
#if defined(MBEDTLS_GCM_C)
int mbedtls_cipher_write_tag( mbedtls_cipher_context_t *ctx,
unsigned char *tag, size_t tag_len )
{
if( NULL == ctx || NULL == ctx->cipher_info || NULL == tag )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
if( MBEDTLS_ENCRYPT != ctx->operation )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
if( MBEDTLS_MODE_GCM == ctx->cipher_info->mode )
return mbedtls_gcm_finish( (mbedtls_gcm_context *) ctx->cipher_ctx, tag, tag_len );
return( 0 );
}
int mbedtls_cipher_check_tag( mbedtls_cipher_context_t *ctx,
const unsigned char *tag, size_t tag_len )
{
int ret;
if( NULL == ctx || NULL == ctx->cipher_info ||
MBEDTLS_DECRYPT != ctx->operation )
{
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
}
if( MBEDTLS_MODE_GCM == ctx->cipher_info->mode )
{
unsigned char check_tag[16];
size_t i;
int diff;
if( tag_len > sizeof( check_tag ) )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
if( 0 != ( ret = mbedtls_gcm_finish( (mbedtls_gcm_context *) ctx->cipher_ctx,
check_tag, tag_len ) ) )
{
return( ret );
}
/* Check the tag in "constant-time" */
for( diff = 0, i = 0; i < tag_len; i++ )
diff |= tag[i] ^ check_tag[i];
if( diff != 0 )
return( MBEDTLS_ERR_CIPHER_AUTH_FAILED );
return( 0 );
}
return( 0 );
}
#endif /* MBEDTLS_GCM_C */
/*
* Packet-oriented wrapper for non-AEAD modes
*/
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 )
{
int ret;
size_t finish_olen;
if( ( ret = mbedtls_cipher_set_iv( ctx, iv, iv_len ) ) != 0 )
return( ret );
if( ( ret = mbedtls_cipher_reset( ctx ) ) != 0 )
return( ret );
if( ( ret = mbedtls_cipher_update( ctx, input, ilen, output, olen ) ) != 0 )
return( ret );
if( ( ret = mbedtls_cipher_finish( ctx, output + *olen, &finish_olen ) ) != 0 )
return( ret );
*olen += finish_olen;
return( 0 );
}
#if defined(MBEDTLS_CIPHER_MODE_AEAD)
/*
* Packet-oriented encryption for AEAD modes
*/
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 )
{
#if defined(MBEDTLS_GCM_C)
if( MBEDTLS_MODE_GCM == ctx->cipher_info->mode )
{
*olen = ilen;
return( mbedtls_gcm_crypt_and_tag( ctx->cipher_ctx, MBEDTLS_GCM_ENCRYPT, ilen,
iv, iv_len, ad, ad_len, input, output,
tag_len, tag ) );
}
#endif /* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CCM_C)
if( MBEDTLS_MODE_CCM == ctx->cipher_info->mode )
{
*olen = ilen;
return( mbedtls_ccm_encrypt_and_tag( ctx->cipher_ctx, ilen,
iv, iv_len, ad, ad_len, input, output,
tag, tag_len ) );
}
#endif /* MBEDTLS_CCM_C */
return( MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE );
}
/*
* Packet-oriented decryption for AEAD modes
*/
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 )
{
#if defined(MBEDTLS_GCM_C)
if( MBEDTLS_MODE_GCM == ctx->cipher_info->mode )
{
int ret;
*olen = ilen;
ret = mbedtls_gcm_auth_decrypt( ctx->cipher_ctx, ilen,
iv, iv_len, ad, ad_len,
tag, tag_len, input, output );
if( ret == MBEDTLS_ERR_GCM_AUTH_FAILED )
ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;
return( ret );
}
#endif /* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CCM_C)
if( MBEDTLS_MODE_CCM == ctx->cipher_info->mode )
{
int ret;
*olen = ilen;
ret = mbedtls_ccm_auth_decrypt( ctx->cipher_ctx, ilen,
iv, iv_len, ad, ad_len,
input, output, tag, tag_len );
if( ret == MBEDTLS_ERR_CCM_AUTH_FAILED )
ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;
return( ret );
}
#endif /* MBEDTLS_CCM_C */
return( MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE );
}
#endif /* MBEDTLS_CIPHER_MODE_AEAD */
#endif /* MBEDTLS_CIPHER_C */
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