1 /* 2 * Copyright (C) 2009 Michael Brown <mbrown (at) fensystems.co.uk>. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License as 6 * published by the Free Software Foundation; either version 2 of the 7 * License, or any later version. 8 * 9 * This program is distributed in the hope that it will be useful, but 10 * WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 17 */ 18 19 FILE_LICENCE ( GPL2_OR_LATER ); 20 21 #include <string.h> 22 #include <assert.h> 23 #include <gpxe/crypto.h> 24 #include <gpxe/cbc.h> 25 26 /** @file 27 * 28 * Cipher-block chaining 29 * 30 */ 31 32 /** 33 * XOR data blocks 34 * 35 * @v src Input data 36 * @v dst Second input data and output data buffer 37 * @v len Length of data 38 */ 39 static void cbc_xor ( const void *src, void *dst, size_t len ) { 40 const uint32_t *srcl = src; 41 uint32_t *dstl = dst; 42 unsigned int i; 43 44 /* Assume that block sizes will always be dword-aligned, for speed */ 45 assert ( ( len % sizeof ( *srcl ) ) == 0 ); 46 47 for ( i = 0 ; i < ( len / sizeof ( *srcl ) ) ; i++ ) 48 dstl[i] ^= srcl[i]; 49 } 50 51 /** 52 * Encrypt data 53 * 54 * @v ctx Context 55 * @v src Data to encrypt 56 * @v dst Buffer for encrypted data 57 * @v len Length of data 58 * @v raw_cipher Underlying cipher algorithm 59 * @v cbc_ctx CBC context 60 */ 61 void cbc_encrypt ( void *ctx, const void *src, void *dst, size_t len, 62 struct cipher_algorithm *raw_cipher, void *cbc_ctx ) { 63 size_t blocksize = raw_cipher->blocksize; 64 65 assert ( ( len % blocksize ) == 0 ); 66 67 while ( len ) { 68 cbc_xor ( src, cbc_ctx, blocksize ); 69 cipher_encrypt ( raw_cipher, ctx, cbc_ctx, dst, blocksize ); 70 memcpy ( cbc_ctx, dst, blocksize ); 71 dst += blocksize; 72 src += blocksize; 73 len -= blocksize; 74 } 75 } 76 77 /** 78 * Decrypt data 79 * 80 * @v ctx Context 81 * @v src Data to decrypt 82 * @v dst Buffer for decrypted data 83 * @v len Length of data 84 * @v raw_cipher Underlying cipher algorithm 85 * @v cbc_ctx CBC context 86 */ 87 void cbc_decrypt ( void *ctx, const void *src, void *dst, size_t len, 88 struct cipher_algorithm *raw_cipher, void *cbc_ctx ) { 89 size_t blocksize = raw_cipher->blocksize; 90 91 assert ( ( len % blocksize ) == 0 ); 92 93 while ( len ) { 94 cipher_decrypt ( raw_cipher, ctx, src, dst, blocksize ); 95 cbc_xor ( cbc_ctx, dst, blocksize ); 96 memcpy ( cbc_ctx, src, blocksize ); 97 dst += blocksize; 98 src += blocksize; 99 len -= blocksize; 100 } 101 } 102
