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mbedtls/library/cipher.c
Andres Amaya Garcia 6a54336897 Fix integer overflows in buffer bound checks 
Fix potential integer overflows in the following functions:
  * mbedtls_md2_update() to be bypassed and cause
  * mbedtls_cipher_update()
  * mbedtls_ctr_drbg_reseed()
This overflows would mainly be exploitable in 32-bit systems and could
cause buffer bound checks to be bypassed.
2017-02-15 23:31:07 +02:00

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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 <= block_size - ctx->unprocessed_len ) ||
( ctx->operation == MBEDTLS_ENCRYPT &&
ilen < block_size - ctx->unprocessed_len ) )
{
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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