yuzu-emu/mbedtls
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Fix for #441 - crypt and hash gcm (#546)

Browse source 
* Fix crypt_and_hash to support decrypting GCM encrypted files

* Fix documentation in crypt_and_hash for the generic case

* Remove unused lastn from crypt_and_hash

lastn is not used with the cipher layer as it already provides padding
and understanding of length of the original data.
This commit is contained in:
Paul Bakker 2016-09-02 22:44:09 +02:00 committed by Simon Butcher
parent cf8c1f4ddb
commit 243f48e1e2
1 changed files with 15 additions and 23 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

38
programs/aes/crypt_and_hash.c
View file

@ -2,7 +2,7 @@
* \brief Generic file encryption program using generic wrappers for configured * \brief Generic file encryption program using generic wrappers for configured
* security. * security.
* *
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0 * SPDX-License-Identifier: Apache-2.0
* *
* Licensed under the Apache License, Version 2.0 (the "License"); you may * Licensed under the Apache License, Version 2.0 (the "License"); you may
@ -74,7 +74,7 @@ int main( void )
int main( int argc, char *argv[] ) int main( int argc, char *argv[] )
{ {
int ret = 1, i, n; int ret = 1, i, n;
int mode, lastn; int mode;
size_t keylen, ilen, olen; size_t keylen, ilen, olen;
FILE *fkey, *fin = NULL, *fout = NULL; FILE *fkey, *fin = NULL, *fout = NULL;
@ -264,7 +264,7 @@ int main( int argc, char *argv[] )
{ {
/* /*
* Generate the initialization vector as: * Generate the initialization vector as:
* IV = SHA-256( filesize || filename )[0..15] * IV = MD( filesize || filename )[0..15]
*/ */
for( i = 0; i < 8; i++ ) for( i = 0; i < 8; i++ )
buffer[i] = (unsigned char)( filesize >> ( i << 3 ) ); buffer[i] = (unsigned char)( filesize >> ( i << 3 ) );
@ -278,15 +278,6 @@ int main( int argc, char *argv[] )
memcpy( IV, digest, 16 ); memcpy( IV, digest, 16 );
/*
* The last four bits in the IV are actually used
* to store the file size modulo the AES block size.
*/
lastn = (int)( filesize & 0x0F );
IV[15] = (unsigned char)
( ( IV[15] & 0xF0 ) | lastn );
/* /*
* Append the IV at the beginning of the output. * Append the IV at the beginning of the output.
*/ */
@ -393,10 +384,10 @@ int main( int argc, char *argv[] )
* The encrypted file must be structured as follows: * The encrypted file must be structured as follows:
* *
* 00 .. 15 Initialization Vector * 00 .. 15 Initialization Vector
* 16 .. 31 AES Encrypted Block #1 * 16 .. 31 Encrypted Block #1
* .. * ..
* N*16 .. (N+1)*16 - 1 AES Encrypted Block #N * N*16 .. (N+1)*16 - 1 Encrypted Block #N
* (N+1)*16 .. (N+1)*16 + 32 HMAC-SHA-256(ciphertext) * (N+1)*16 .. (N+1)*16 + n Hash(ciphertext)
*/ */
if( filesize < 16 + mbedtls_md_get_size( md_info ) ) if( filesize < 16 + mbedtls_md_get_size( md_info ) )
{ {
@ -413,7 +404,8 @@ int main( int argc, char *argv[] )
/* /*
* Check the file size. * Check the file size.
*/ */
if( ( ( filesize - mbedtls_md_get_size( md_info ) ) % if( cipher_info->mode != MBEDTLS_MODE_GCM &&
( ( filesize - mbedtls_md_get_size( md_info ) ) %
mbedtls_cipher_get_block_size( &cipher_ctx ) ) != 0 ) mbedtls_cipher_get_block_size( &cipher_ctx ) ) != 0 )
{ {
mbedtls_fprintf( stderr, "File content not a multiple of the block size (%d).\n", mbedtls_fprintf( stderr, "File content not a multiple of the block size (%d).\n",
@ -436,7 +428,6 @@ int main( int argc, char *argv[] )
} }
memcpy( IV, buffer, 16 ); memcpy( IV, buffer, 16 );
lastn = IV[15] & 0x0F;
/* /*
* Hash the IV and the secret key together 8192 times * Hash the IV and the secret key together 8192 times
@ -481,18 +472,19 @@ int main( int argc, char *argv[] )
*/ */
for( offset = 0; offset < filesize; offset += mbedtls_cipher_get_block_size( &cipher_ctx ) ) for( offset = 0; offset < filesize; offset += mbedtls_cipher_get_block_size( &cipher_ctx ) )
{ {
if( fread( buffer, 1, mbedtls_cipher_get_block_size( &cipher_ctx ), fin ) != ilen = ( (unsigned int) filesize - offset > mbedtls_cipher_get_block_size( &cipher_ctx ) ) ?
(size_t) 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_fprintf( stderr, "fread(%d bytes) failed\n",
mbedtls_cipher_get_block_size( &cipher_ctx ) ); mbedtls_cipher_get_block_size( &cipher_ctx ) );
goto exit; goto exit;
} }
mbedtls_md_hmac_update( &md_ctx, buffer, mbedtls_cipher_get_block_size( &cipher_ctx ) ); mbedtls_md_hmac_update( &md_ctx, buffer, ilen );
if( mbedtls_cipher_update( &cipher_ctx, buffer, if( mbedtls_cipher_update( &cipher_ctx, buffer, ilen, output,
mbedtls_cipher_get_block_size( &cipher_ctx ), &olen ) != 0 )
output, &olen ) != 0 )
{ {
mbedtls_fprintf( stderr, "mbedtls_cipher_update() returned error\n" ); mbedtls_fprintf( stderr, "mbedtls_cipher_update() returned error\n" );
goto exit; goto exit;