cbc128.c

/* ====================================================================
 * Copyright (c) 2008 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
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 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
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 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
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 * 5. Products derived from this software may not be called "OpenSSL"
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 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
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 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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#include <openssl/crypto.h>
#include "modes_lcl.h"
#include <string.h>

#ifndef MODES_DEBUG
# ifndef NDEBUG
#  define NDEBUG
# endif
#endif
#include <assert.h>

#ifndef STRICT_ALIGNMENT
#  define STRICT_ALIGNMENT 0
#endif

void CRYPTO_cbc128_encrypt(const unsigned char *in, unsigned char *out,
			size_t len, const void *key,
			unsigned char ivec[16], block128_f block)
{
	size_t n;
	const unsigned char *iv = ivec;

	assert(in && out && key && ivec);

#if !defined(OPENSSL_SMALL_FOOTPRINT)
	if (STRICT_ALIGNMENT &&
	    ((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) {
		while (len>=16) {
			for(n=0; n<16; ++n)
				out[n] = in[n] ^ iv[n];
			(*block)(out, out, key);
			iv = out;
			len -= 16;
			in  += 16;
			out += 16;
		}
	} else {
		while (len>=16) {
			for(n=0; n<16; n+=sizeof(size_t))
				*(size_t*)(out+n) =
				*(size_t*)(in+n) ^ *(size_t*)(iv+n);
			(*block)(out, out, key);
			iv = out;
			len -= 16;
			in  += 16;
			out += 16;
		}
	}
#endif
	while (len) {
		for(n=0; n<16 && n<len; ++n)
			out[n] = in[n] ^ iv[n];
		for(; n<16; ++n)
			out[n] = iv[n];
		(*block)(out, out, key);
		iv = out;
		if (len<=16) break;
		len -= 16;
		in  += 16;
		out += 16;
	}
	memcpy(ivec,iv,16);
}

void CRYPTO_cbc128_decrypt(const unsigned char *in, unsigned char *out,
			size_t len, const void *key,
			unsigned char ivec[16], block128_f block)
{
	size_t n;
	union { size_t t[16/sizeof(size_t)]; unsigned char c[16]; } tmp;

	assert(in && out && key && ivec);

#if !defined(OPENSSL_SMALL_FOOTPRINT)
	if (in != out) {
		const unsigned char *iv = ivec;

		if (STRICT_ALIGNMENT &&
		    ((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) {
			while (len>=16) {
				(*block)(in, out, key);
				for(n=0; n<16; ++n)
					out[n] ^= iv[n];
				iv = in;
				len -= 16;
				in  += 16;
				out += 16;
			}
		}
		else  if (16%sizeof(size_t) == 0) { /* always true */
			while (len>=16) {
				size_t *out_t=(size_t *)out, *iv_t=(size_t *)iv;

				(*block)(in, out, key);
				for(n=0; n<16/sizeof(size_t); n++)
					out_t[n] ^= iv_t[n];
				iv = in;
				len -= 16;
				in  += 16;
				out += 16;
			}
		}
		memcpy(ivec,iv,16);
	} else {
		if (STRICT_ALIGNMENT &&
		    ((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) {
			unsigned char c;
			while (len>=16) {
				(*block)(in, tmp.c, key);
				for(n=0; n<16; ++n) {
					c = in[n];
					out[n] = tmp.c[n] ^ ivec[n];
					ivec[n] = c;
				}
				len -= 16;
				in  += 16;
				out += 16;
			}
		}
		else if (16%sizeof(size_t) == 0) { /* always true */
			while (len>=16) {
				size_t c, *out_t=(size_t *)out, *ivec_t=(size_t *)ivec;
				const size_t *in_t=(const size_t *)in;

				(*block)(in, tmp.c, key);
				for(n=0; n<16/sizeof(size_t); n++) {
					c = in_t[n];
					out_t[n] = tmp.t[n] ^ ivec_t[n];
					ivec_t[n] = c;
				}
				len -= 16;
				in  += 16;
				out += 16;
			}
		}
	}
#endif
	while (len) {
		unsigned char c;
		(*block)(in, tmp.c, key);
		for(n=0; n<16 && n<len; ++n) {
			c = in[n];
			out[n] = tmp.c[n] ^ ivec[n];
			ivec[n] = c;
		}
		if (len<=16) {
			for (; n<16; ++n)
				ivec[n] = in[n];
			break;
		}
		len -= 16;
		in  += 16;
		out += 16;
	}
}