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mbedtls/programs/aes/crypt_and_hash.c
Hanno Becker f601ec5f34 Reliably zeroize sensitive data in Crypt-and-Hash sample application 
The AES sample application programs/aes/crypt_and_hash could miss
zeroizing the stack-based key buffer in case of an error during
operation. This commit fixes this and also clears all command line
arguments (one of which might be the key) before exit.
2017-07-28 22:28:08 +01:00

554 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>
#define mbedtls_fprintf fprintf
#define mbedtls_printf printf
#endif
#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
int main( int argc, char *argv[] )
{
int ret = 1, i, n;
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 and clean the 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;
}
}
ret = 0;
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++ )
memset( argv[i], 0, strlen( argv[i] ) );
memset( IV, 0, sizeof( IV ) );
memset( key, 0, sizeof( key ) );
memset( buffer, 0, sizeof( buffer ) );
memset( output, 0, sizeof( output ) );
memset( digest, 0, sizeof( digest ) );
mbedtls_cipher_free( &cipher_ctx );
mbedtls_md_free( &md_ctx );
return( ret );
}
#endif /* MBEDTLS_CIPHER_C && MBEDTLS_MD_C && MBEDTLS_FS_IO */
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