| /* |
| * AES-256 file encryption program |
| * |
| * Copyright (C) 2006-2010, Brainspark B.V. |
| * |
| * This file is part of PolarSSL (http://www.polarssl.org) |
| * Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org> |
| * |
| * All rights reserved. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License along |
| * with this program; if not, write to the Free Software Foundation, Inc., |
| * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| */ |
| |
| #ifndef _CRT_SECURE_NO_DEPRECATE |
| #define _CRT_SECURE_NO_DEPRECATE 1 |
| #endif |
| |
| #if defined(WIN32) |
| #include <windows.h> |
| #include <io.h> |
| #else |
| #include <sys/types.h> |
| #include <unistd.h> |
| #endif |
| |
| #include <string.h> |
| #include <stdlib.h> |
| #include <stdio.h> |
| #include <time.h> |
| |
| #include "polarssl/aes.h" |
| #include "polarssl/sha2.h" |
| |
| #define MODE_ENCRYPT 0 |
| #define MODE_DECRYPT 1 |
| |
| #define USAGE \ |
| "\n aescrypt2 <mode> <input filename> <output filename> <key>\n" \ |
| "\n <mode>: 0 = encrypt, 1 = decrypt\n" \ |
| "\n example: aescrypt2 0 file file.aes hex:E76B2413958B00E193\n" \ |
| "\n" |
| |
| int main( int argc, char *argv[] ) |
| { |
| int ret = 1, i, n; |
| int keylen, mode, lastn; |
| FILE *fkey, *fin = NULL, *fout = NULL; |
| |
| char *p; |
| unsigned char IV[16]; |
| unsigned char key[512]; |
| unsigned char digest[32]; |
| unsigned char buffer[1024]; |
| |
| aes_context aes_ctx; |
| sha2_context sha_ctx; |
| |
| #if defined(WIN32) |
| LARGE_INTEGER li_size; |
| __int64 filesize, offset; |
| #else |
| off_t filesize, offset; |
| #endif |
| |
| /* |
| * Parse the command-line arguments. |
| */ |
| if( argc != 5 ) |
| { |
| printf( USAGE ); |
| |
| #if defined(WIN32) |
| 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 ) |
| { |
| fprintf( stderr, "invalide operation mode\n" ); |
| goto exit; |
| } |
| |
| if( strcmp( argv[2], argv[3] ) == 0 ) |
| { |
| fprintf( stderr, "input and output filenames must differ\n" ); |
| goto exit; |
| } |
| |
| if( ( fin = fopen( argv[2], "rb" ) ) == NULL ) |
| { |
| fprintf( stderr, "fopen(%s,rb) failed\n", argv[2] ); |
| goto exit; |
| } |
| |
| if( ( fout = fopen( argv[3], "wb+" ) ) == NULL ) |
| { |
| fprintf( stderr, "fopen(%s,wb+) failed\n", argv[3] ); |
| goto exit; |
| } |
| |
| /* |
| * Read the secret key and clean the command line. |
| */ |
| if( ( fkey = fopen( argv[4], "rb" ) ) != NULL ) |
| { |
| keylen = fread( key, 1, sizeof( key ), fkey ); |
| fclose( fkey ); |
| } |
| else |
| { |
| if( memcmp( argv[4], "hex:", 4 ) == 0 ) |
| { |
| p = &argv[4][4]; |
| keylen = 0; |
| |
| while( sscanf( p, "%02X", &n ) > 0 && |
| keylen < (int) sizeof( key ) ) |
| { |
| key[keylen++] = (unsigned char) n; |
| p += 2; |
| } |
| } |
| else |
| { |
| keylen = strlen( argv[4] ); |
| |
| if( keylen > (int) sizeof( key ) ) |
| keylen = (int) sizeof( key ); |
| |
| memcpy( key, argv[4], keylen ); |
| } |
| } |
| |
| memset( argv[4], 0, strlen( argv[4] ) ); |
| |
| #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 ) |
| { |
| 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 |
| |
| if( fseek( fin, 0, SEEK_SET ) < 0 ) |
| { |
| fprintf( stderr, "fseek(0,SEEK_SET) failed\n" ); |
| goto exit; |
| } |
| |
| if( mode == MODE_ENCRYPT ) |
| { |
| /* |
| * Generate the initialization vector as: |
| * IV = SHA-256( filesize || filename )[0..15] |
| */ |
| for( i = 0; i < 8; i++ ) |
| buffer[i] = (unsigned char)( filesize >> ( i << 3 ) ); |
| |
| p = argv[2]; |
| |
| sha2_starts( &sha_ctx, 0 ); |
| sha2_update( &sha_ctx, buffer, 8 ); |
| sha2_update( &sha_ctx, (unsigned char *) p, strlen( p ) ); |
| sha2_finish( &sha_ctx, digest ); |
| |
| 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. |
| */ |
| if( fwrite( IV, 1, 16, fout ) != 16 ) |
| { |
| 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++ ) |
| { |
| sha2_starts( &sha_ctx, 0 ); |
| sha2_update( &sha_ctx, digest, 32 ); |
| sha2_update( &sha_ctx, key, keylen ); |
| sha2_finish( &sha_ctx, digest ); |
| } |
| |
| memset( key, 0, sizeof( key ) ); |
| aes_setkey_enc( &aes_ctx, digest, 256 ); |
| sha2_hmac_starts( &sha_ctx, digest, 32, 0 ); |
| |
| /* |
| * Encrypt and write the ciphertext. |
| */ |
| for( offset = 0; offset < filesize; offset += 16 ) |
| { |
| n = ( filesize - offset > 16 ) ? 16 : (int) |
| ( filesize - offset ); |
| |
| if( fread( buffer, 1, n, fin ) != (size_t) n ) |
| { |
| fprintf( stderr, "fread(%d bytes) failed\n", n ); |
| goto exit; |
| } |
| |
| for( i = 0; i < 16; i++ ) |
| buffer[i] = (unsigned char)( buffer[i] ^ IV[i] ); |
| |
| aes_crypt_ecb( &aes_ctx, AES_ENCRYPT, buffer, buffer ); |
| sha2_hmac_update( &sha_ctx, buffer, 16 ); |
| |
| if( fwrite( buffer, 1, 16, fout ) != 16 ) |
| { |
| fprintf( stderr, "fwrite(%d bytes) failed\n", 16 ); |
| goto exit; |
| } |
| |
| memcpy( IV, buffer, 16 ); |
| } |
| |
| /* |
| * Finally write the HMAC. |
| */ |
| sha2_hmac_finish( &sha_ctx, digest ); |
| |
| if( fwrite( digest, 1, 32, fout ) != 32 ) |
| { |
| fprintf( stderr, "fwrite(%d bytes) failed\n", 16 ); |
| goto exit; |
| } |
| } |
| |
| if( mode == MODE_DECRYPT ) |
| { |
| unsigned char tmp[16]; |
| |
| /* |
| * The encrypted file must be structured as follows: |
| * |
| * 00 .. 15 Initialization Vector |
| * 16 .. 31 AES Encrypted Block #1 |
| * .. |
| * N*16 .. (N+1)*16 - 1 AES Encrypted Block #N |
| * (N+1)*16 .. (N+1)*16 + 32 HMAC-SHA-256(ciphertext) |
| */ |
| if( filesize < 48 ) |
| { |
| fprintf( stderr, "File too short to be encrypted.\n" ); |
| goto exit; |
| } |
| |
| if( ( filesize & 0x0F ) != 0 ) |
| { |
| fprintf( stderr, "File size not a multiple of 16.\n" ); |
| goto exit; |
| } |
| |
| /* |
| * Substract the IV + HMAC length. |
| */ |
| filesize -= ( 16 + 32 ); |
| |
| /* |
| * Read the IV and original filesize modulo 16. |
| */ |
| if( fread( buffer, 1, 16, fin ) != 16 ) |
| { |
| fprintf( stderr, "fread(%d bytes) failed\n", 16 ); |
| goto exit; |
| } |
| |
| memcpy( IV, buffer, 16 ); |
| lastn = IV[15] & 0x0F; |
| |
| /* |
| * 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++ ) |
| { |
| sha2_starts( &sha_ctx, 0 ); |
| sha2_update( &sha_ctx, digest, 32 ); |
| sha2_update( &sha_ctx, key, keylen ); |
| sha2_finish( &sha_ctx, digest ); |
| } |
| |
| memset( key, 0, sizeof( key ) ); |
| aes_setkey_dec( &aes_ctx, digest, 256 ); |
| sha2_hmac_starts( &sha_ctx, digest, 32, 0 ); |
| |
| /* |
| * Decrypt and write the plaintext. |
| */ |
| for( offset = 0; offset < filesize; offset += 16 ) |
| { |
| if( fread( buffer, 1, 16, fin ) != 16 ) |
| { |
| fprintf( stderr, "fread(%d bytes) failed\n", 16 ); |
| goto exit; |
| } |
| |
| memcpy( tmp, buffer, 16 ); |
| |
| sha2_hmac_update( &sha_ctx, buffer, 16 ); |
| aes_crypt_ecb( &aes_ctx, AES_DECRYPT, buffer, buffer ); |
| |
| for( i = 0; i < 16; i++ ) |
| buffer[i] = (unsigned char)( buffer[i] ^ IV[i] ); |
| |
| memcpy( IV, tmp, 16 ); |
| |
| n = ( lastn > 0 && offset == filesize - 16 ) |
| ? lastn : 16; |
| |
| if( fwrite( buffer, 1, n, fout ) != (size_t) n ) |
| { |
| fprintf( stderr, "fwrite(%d bytes) failed\n", n ); |
| goto exit; |
| } |
| } |
| |
| /* |
| * Verify the message authentication code. |
| */ |
| sha2_hmac_finish( &sha_ctx, digest ); |
| |
| if( fread( buffer, 1, 32, fin ) != 32 ) |
| { |
| fprintf( stderr, "fread(%d bytes) failed\n", 32 ); |
| goto exit; |
| } |
| |
| if( memcmp( digest, buffer, 32 ) != 0 ) |
| { |
| fprintf( stderr, "HMAC check failed: wrong key, " |
| "or file corrupted.\n" ); |
| goto exit; |
| } |
| } |
| |
| ret = 0; |
| |
| exit: |
| if( fin ) |
| fclose( fin ); |
| if( fout ) |
| fclose( fout ); |
| |
| memset( buffer, 0, sizeof( buffer ) ); |
| memset( digest, 0, sizeof( digest ) ); |
| |
| memset( &aes_ctx, 0, sizeof( aes_context ) ); |
| memset( &sha_ctx, 0, sizeof( sha2_context ) ); |
| |
| return( ret ); |
| } |