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mbedtls/programs/aes/crypt_and_hash.c
Hanno Becker 9a1a151a1a Zeroize sensitive data in aescrypt2 and crypt_and_hash examples 
This commit replaces multiple `memset()` calls in the example
programs aes/aescrypt2.c and aes/crypt_and_hash.c by calls to
the reliable zeroization function `mbedtls_zeroize()`.

While not a security issue because the code is in the example
programs, it's bad practice and should be fixed.
2018-10-15 13:26:37 +01:00

565 lines
16 KiB
C
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/*
* \brief Generic file encryption program using generic wrappers for configured
* security.
*
* Copyright (C) 2006-2016, 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_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#include <stdlib.h>
#define mbedtls_fprintf fprintf
#define mbedtls_printf printf
#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
#endif /* MBEDTLS_PLATFORM_C */
#if defined(MBEDTLS_CIPHER_C) && defined(MBEDTLS_MD_C) && \
defined(MBEDTLS_FS_IO)
#include "mbedtls/cipher.h"
#include "mbedtls/md.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#endif
#if defined(_WIN32)
#include <windows.h>
#if !defined(_WIN32_WCE)
#include <io.h>
#endif
#else
#include <sys/types.h>
#include <unistd.h>
#endif
#define MODE_ENCRYPT 0
#define MODE_DECRYPT 1
#define USAGE \
"\n crypt_and_hash <mode> <input filename> <output filename> <cipher> <mbedtls_md> <key>\n" \
"\n <mode>: 0 = encrypt, 1 = decrypt\n" \
"\n example: crypt_and_hash 0 file file.aes AES-128-CBC SHA1 hex:E76B2413958B00E193\n" \
"\n"
#if !defined(MBEDTLS_CIPHER_C) || !defined(MBEDTLS_MD_C) || \
!defined(MBEDTLS_FS_IO)
int main( void )
{
mbedtls_printf("MBEDTLS_CIPHER_C and/or MBEDTLS_MD_C and/or MBEDTLS_FS_IO not defined.\n");
return( 0 );
}
#else
/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize( void *v, size_t n ) {
volatile unsigned char *p = v; while( n-- ) *p++ = 0;
}
int main( int argc, char *argv[] )
{
int ret = 1, i, n;
int exit_code = MBEDTLS_EXIT_FAILURE;
int mode;
size_t keylen, ilen, olen;
FILE *fkey, *fin = NULL, *fout = NULL;
char *p;
unsigned char IV[16];
unsigned char key[512];
unsigned char digest[MBEDTLS_MD_MAX_SIZE];
unsigned char buffer[1024];
unsigned char output[1024];
unsigned char diff;
const mbedtls_cipher_info_t *cipher_info;
const mbedtls_md_info_t *md_info;
mbedtls_cipher_context_t cipher_ctx;
mbedtls_md_context_t md_ctx;
#if defined(_WIN32_WCE)
long filesize, offset;
#elif defined(_WIN32)
LARGE_INTEGER li_size;
__int64 filesize, offset;
#else
off_t filesize, offset;
#endif
mbedtls_cipher_init( &cipher_ctx );
mbedtls_md_init( &md_ctx );
/*
* Parse the command-line arguments.
*/
if( argc != 7 )
{
const int *list;
mbedtls_printf( USAGE );
mbedtls_printf( "Available ciphers:\n" );
list = mbedtls_cipher_list();
while( *list )
{
cipher_info = mbedtls_cipher_info_from_type( *list );
mbedtls_printf( " %s\n", cipher_info->name );
list++;
}
mbedtls_printf( "\nAvailable message digests:\n" );
list = mbedtls_md_list();
while( *list )
{
md_info = mbedtls_md_info_from_type( *list );
mbedtls_printf( " %s\n", mbedtls_md_get_name( md_info ) );
list++;
}
#if defined(_WIN32)
mbedtls_printf( "\n Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
goto exit;
}
mode = atoi( argv[1] );
if( mode != MODE_ENCRYPT && mode != MODE_DECRYPT )
{
mbedtls_fprintf( stderr, "invalid operation mode\n" );
goto exit;
}
if( strcmp( argv[2], argv[3] ) == 0 )
{
mbedtls_fprintf( stderr, "input and output filenames must differ\n" );
goto exit;
}
if( ( fin = fopen( argv[2], "rb" ) ) == NULL )
{
mbedtls_fprintf( stderr, "fopen(%s,rb) failed\n", argv[2] );
goto exit;
}
if( ( fout = fopen( argv[3], "wb+" ) ) == NULL )
{
mbedtls_fprintf( stderr, "fopen(%s,wb+) failed\n", argv[3] );
goto exit;
}
/*
* Read the Cipher and MD from the command line
*/
cipher_info = mbedtls_cipher_info_from_string( argv[4] );
if( cipher_info == NULL )
{
mbedtls_fprintf( stderr, "Cipher '%s' not found\n", argv[4] );
goto exit;
}
if( ( ret = mbedtls_cipher_setup( &cipher_ctx, cipher_info) ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_cipher_setup failed\n" );
goto exit;
}
md_info = mbedtls_md_info_from_string( argv[5] );
if( md_info == NULL )
{
mbedtls_fprintf( stderr, "Message Digest '%s' not found\n", argv[5] );
goto exit;
}
if( mbedtls_md_setup( &md_ctx, md_info, 1 ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_md_setup failed\n" );
goto exit;
}
/*
* Read the secret key from file or command line
*/
if( ( fkey = fopen( argv[6], "rb" ) ) != NULL )
{
keylen = fread( key, 1, sizeof( key ), fkey );
fclose( fkey );
}
else
{
if( memcmp( argv[6], "hex:", 4 ) == 0 )
{
p = &argv[6][4];
keylen = 0;
while( sscanf( p, "%02X", &n ) > 0 &&
keylen < (int) sizeof( key ) )
{
key[keylen++] = (unsigned char) n;
p += 2;
}
}
else
{
keylen = strlen( argv[6] );
if( keylen > (int) sizeof( key ) )
keylen = (int) sizeof( key );
memcpy( key, argv[6], keylen );
}
}
#if defined(_WIN32_WCE)
filesize = fseek( fin, 0L, SEEK_END );
#else
#if defined(_WIN32)
/*
* Support large files (> 2Gb) on Win32
*/
li_size.QuadPart = 0;
li_size.LowPart =
SetFilePointer( (HANDLE) _get_osfhandle( _fileno( fin ) ),
li_size.LowPart, &li_size.HighPart, FILE_END );
if( li_size.LowPart == 0xFFFFFFFF && GetLastError() != NO_ERROR )
{
mbedtls_fprintf( stderr, "SetFilePointer(0,FILE_END) failed\n" );
goto exit;
}
filesize = li_size.QuadPart;
#else
if( ( filesize = lseek( fileno( fin ), 0, SEEK_END ) ) < 0 )
{
perror( "lseek" );
goto exit;
}
#endif
#endif
if( fseek( fin, 0, SEEK_SET ) < 0 )
{
mbedtls_fprintf( stderr, "fseek(0,SEEK_SET) failed\n" );
goto exit;
}
if( mode == MODE_ENCRYPT )
{
/*
* Generate the initialization vector as:
* IV = MD( filesize || filename )[0..15]
*/
for( i = 0; i < 8; i++ )
buffer[i] = (unsigned char)( filesize >> ( i << 3 ) );
p = argv[2];
mbedtls_md_starts( &md_ctx );
mbedtls_md_update( &md_ctx, buffer, 8 );
mbedtls_md_update( &md_ctx, (unsigned char *) p, strlen( p ) );
mbedtls_md_finish( &md_ctx, digest );
memcpy( IV, digest, 16 );
/*
* Append the IV at the beginning of the output.
*/
if( fwrite( IV, 1, 16, fout ) != 16 )
{
mbedtls_fprintf( stderr, "fwrite(%d bytes) failed\n", 16 );
goto exit;
}
/*
* Hash the IV and the secret key together 8192 times
* using the result to setup the AES context and HMAC.
*/
memset( digest, 0, 32 );
memcpy( digest, IV, 16 );
for( i = 0; i < 8192; i++ )
{
mbedtls_md_starts( &md_ctx );
mbedtls_md_update( &md_ctx, digest, 32 );
mbedtls_md_update( &md_ctx, key, keylen );
mbedtls_md_finish( &md_ctx, digest );
}
if( mbedtls_cipher_setkey( &cipher_ctx, digest, cipher_info->key_bitlen,
MBEDTLS_ENCRYPT ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_cipher_setkey() returned error\n");
goto exit;
}
if( mbedtls_cipher_set_iv( &cipher_ctx, IV, 16 ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_cipher_set_iv() returned error\n");
goto exit;
}
if( mbedtls_cipher_reset( &cipher_ctx ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_cipher_reset() returned error\n");
goto exit;
}
mbedtls_md_hmac_starts( &md_ctx, digest, 32 );
/*
* Encrypt and write the ciphertext.
*/
for( offset = 0; offset < filesize; offset += mbedtls_cipher_get_block_size( &cipher_ctx ) )
{
ilen = ( (unsigned int) filesize - offset > mbedtls_cipher_get_block_size( &cipher_ctx ) ) ?
mbedtls_cipher_get_block_size( &cipher_ctx ) : (unsigned int) ( filesize - offset );
if( fread( buffer, 1, ilen, fin ) != ilen )
{
mbedtls_fprintf( stderr, "fread(%ld bytes) failed\n", (long) ilen );
goto exit;
}
if( mbedtls_cipher_update( &cipher_ctx, buffer, ilen, output, &olen ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_cipher_update() returned error\n");
goto exit;
}
mbedtls_md_hmac_update( &md_ctx, output, olen );
if( fwrite( output, 1, olen, fout ) != olen )
{
mbedtls_fprintf( stderr, "fwrite(%ld bytes) failed\n", (long) olen );
goto exit;
}
}
if( mbedtls_cipher_finish( &cipher_ctx, output, &olen ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_cipher_finish() returned error\n" );
goto exit;
}
mbedtls_md_hmac_update( &md_ctx, output, olen );
if( fwrite( output, 1, olen, fout ) != olen )
{
mbedtls_fprintf( stderr, "fwrite(%ld bytes) failed\n", (long) olen );
goto exit;
}
/*
* Finally write the HMAC.
*/
mbedtls_md_hmac_finish( &md_ctx, digest );
if( fwrite( digest, 1, mbedtls_md_get_size( md_info ), fout ) != mbedtls_md_get_size( md_info ) )
{
mbedtls_fprintf( stderr, "fwrite(%d bytes) failed\n", mbedtls_md_get_size( md_info ) );
goto exit;
}
}
if( mode == MODE_DECRYPT )
{
/*
* The encrypted file must be structured as follows:
*
* 00 .. 15 Initialization Vector
* 16 .. 31 Encrypted Block #1
* ..
* N*16 .. (N+1)*16 - 1 Encrypted Block #N
* (N+1)*16 .. (N+1)*16 + n Hash(ciphertext)
*/
if( filesize < 16 + mbedtls_md_get_size( md_info ) )
{
mbedtls_fprintf( stderr, "File too short to be encrypted.\n" );
goto exit;
}
if( mbedtls_cipher_get_block_size( &cipher_ctx ) == 0 )
{
mbedtls_fprintf( stderr, "Invalid cipher block size: 0. \n" );
goto exit;
}
/*
* Check the file size.
*/
if( cipher_info->mode != MBEDTLS_MODE_GCM &&
( ( filesize - mbedtls_md_get_size( md_info ) ) %
mbedtls_cipher_get_block_size( &cipher_ctx ) ) != 0 )
{
mbedtls_fprintf( stderr, "File content not a multiple of the block size (%d).\n",
mbedtls_cipher_get_block_size( &cipher_ctx ));
goto exit;
}
/*
* Subtract the IV + HMAC length.
*/
filesize -= ( 16 + mbedtls_md_get_size( md_info ) );
/*
* Read the IV and original filesize modulo 16.
*/
if( fread( buffer, 1, 16, fin ) != 16 )
{
mbedtls_fprintf( stderr, "fread(%d bytes) failed\n", 16 );
goto exit;
}
memcpy( IV, buffer, 16 );
/*
* Hash the IV and the secret key together 8192 times
* using the result to setup the AES context and HMAC.
*/
memset( digest, 0, 32 );
memcpy( digest, IV, 16 );
for( i = 0; i < 8192; i++ )
{
mbedtls_md_starts( &md_ctx );
mbedtls_md_update( &md_ctx, digest, 32 );
mbedtls_md_update( &md_ctx, key, keylen );
mbedtls_md_finish( &md_ctx, digest );
}
if( mbedtls_cipher_setkey( &cipher_ctx, digest, cipher_info->key_bitlen,
MBEDTLS_DECRYPT ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_cipher_setkey() returned error\n" );
goto exit;
}
if( mbedtls_cipher_set_iv( &cipher_ctx, IV, 16 ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_cipher_set_iv() returned error\n" );
goto exit;
}
if( mbedtls_cipher_reset( &cipher_ctx ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_cipher_reset() returned error\n" );
goto exit;
}
mbedtls_md_hmac_starts( &md_ctx, digest, 32 );
/*
* Decrypt and write the plaintext.
*/
for( offset = 0; offset < filesize; offset += mbedtls_cipher_get_block_size( &cipher_ctx ) )
{
ilen = ( (unsigned int) filesize - offset > mbedtls_cipher_get_block_size( &cipher_ctx ) ) ?
mbedtls_cipher_get_block_size( &cipher_ctx ) : (unsigned int) ( filesize - offset );
if( fread( buffer, 1, ilen, fin ) != ilen )
{
mbedtls_fprintf( stderr, "fread(%d bytes) failed\n",
mbedtls_cipher_get_block_size( &cipher_ctx ) );
goto exit;
}
mbedtls_md_hmac_update( &md_ctx, buffer, ilen );
if( mbedtls_cipher_update( &cipher_ctx, buffer, ilen, output,
&olen ) != 0 )
{
mbedtls_fprintf( stderr, "mbedtls_cipher_update() returned error\n" );
goto exit;
}
if( fwrite( output, 1, olen, fout ) != olen )
{
mbedtls_fprintf( stderr, "fwrite(%ld bytes) failed\n", (long) olen );
goto exit;
}
}
/*
* Verify the message authentication code.
*/
mbedtls_md_hmac_finish( &md_ctx, digest );
if( fread( buffer, 1, mbedtls_md_get_size( md_info ), fin ) != mbedtls_md_get_size( md_info ) )
{
mbedtls_fprintf( stderr, "fread(%d bytes) failed\n", mbedtls_md_get_size( md_info ) );
goto exit;
}
/* Use constant-time buffer comparison */
diff = 0;
for( i = 0; i < mbedtls_md_get_size( md_info ); i++ )
diff |= digest[i] ^ buffer[i];
if( diff != 0 )
{
mbedtls_fprintf( stderr, "HMAC check failed: wrong key, "
"or file corrupted.\n" );
goto exit;
}
/*
* Write the final block of data
*/
mbedtls_cipher_finish( &cipher_ctx, output, &olen );
if( fwrite( output, 1, olen, fout ) != olen )
{
mbedtls_fprintf( stderr, "fwrite(%ld bytes) failed\n", (long) olen );
goto exit;
}
}
exit_code = MBEDTLS_EXIT_SUCCESS;
exit:
if( fin )
fclose( fin );
if( fout )
fclose( fout );
/* Zeroize all command line arguments to also cover
the case when the user has missed or reordered some,
in which case the key might not be in argv[6]. */
for( i = 0; i < argc; i++ )
mbedtls_zeroize( argv[i], strlen( argv[i] ) );
mbedtls_zeroize( IV, sizeof( IV ) );
mbedtls_zeroize( key, sizeof( key ) );
mbedtls_zeroize( buffer, sizeof( buffer ) );
mbedtls_zeroize( output, sizeof( output ) );
mbedtls_zeroize( digest, sizeof( digest ) );
mbedtls_cipher_free( &cipher_ctx );
mbedtls_md_free( &md_ctx );
return( exit_code );
}
#endif /* MBEDTLS_CIPHER_C && MBEDTLS_MD_C && MBEDTLS_FS_IO */
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