mirror of
https://github.com/xcat2/xcat-dep.git
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102 lines
2.6 KiB
C
102 lines
2.6 KiB
C
/*
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* Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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FILE_LICENCE ( GPL2_OR_LATER );
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#include <string.h>
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#include <assert.h>
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#include <ipxe/crypto.h>
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#include <ipxe/cbc.h>
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/** @file
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*
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* Cipher-block chaining
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*
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*/
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/**
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* XOR data blocks
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*
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* @v src Input data
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* @v dst Second input data and output data buffer
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* @v len Length of data
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*/
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static void cbc_xor ( const void *src, void *dst, size_t len ) {
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const uint32_t *srcl = src;
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uint32_t *dstl = dst;
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unsigned int i;
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/* Assume that block sizes will always be dword-aligned, for speed */
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assert ( ( len % sizeof ( *srcl ) ) == 0 );
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for ( i = 0 ; i < ( len / sizeof ( *srcl ) ) ; i++ )
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dstl[i] ^= srcl[i];
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}
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/**
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* Encrypt data
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*
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* @v ctx Context
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* @v src Data to encrypt
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* @v dst Buffer for encrypted data
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* @v len Length of data
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* @v raw_cipher Underlying cipher algorithm
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* @v cbc_ctx CBC context
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*/
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void cbc_encrypt ( void *ctx, const void *src, void *dst, size_t len,
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struct cipher_algorithm *raw_cipher, void *cbc_ctx ) {
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size_t blocksize = raw_cipher->blocksize;
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assert ( ( len % blocksize ) == 0 );
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while ( len ) {
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cbc_xor ( src, cbc_ctx, blocksize );
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cipher_encrypt ( raw_cipher, ctx, cbc_ctx, dst, blocksize );
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memcpy ( cbc_ctx, dst, blocksize );
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dst += blocksize;
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src += blocksize;
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len -= blocksize;
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}
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}
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/**
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* Decrypt data
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*
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* @v ctx Context
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* @v src Data to decrypt
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* @v dst Buffer for decrypted data
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* @v len Length of data
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* @v raw_cipher Underlying cipher algorithm
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* @v cbc_ctx CBC context
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*/
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void cbc_decrypt ( void *ctx, const void *src, void *dst, size_t len,
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struct cipher_algorithm *raw_cipher, void *cbc_ctx ) {
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size_t blocksize = raw_cipher->blocksize;
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assert ( ( len % blocksize ) == 0 );
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while ( len ) {
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cipher_decrypt ( raw_cipher, ctx, src, dst, blocksize );
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cbc_xor ( cbc_ctx, dst, blocksize );
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memcpy ( cbc_ctx, src, blocksize );
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dst += blocksize;
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src += blocksize;
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len -= blocksize;
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}
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}
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