/* ====================================================================
* 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.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* 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.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 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/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
*/
#include <openssl/crypto.h>
#include "modes_lcl.h"
#include <string.h>
#ifndef MODES_DEBUG
# ifndef NDEBUG
# define NDEBUG
# endif
#endif
#include <assert.h>
/* The input and output encrypted as though 128bit cfb mode is being
* used. The extra state information to record how much of the
* 128bit block we have used is contained in *num;
*/
void CRYPTO_cfb128_encrypt(const unsigned char *in, unsigned char *out,
size_t len, const void *key,
unsigned char ivec[16], int *num,
int enc, block128_f block)
{
unsigned int n;
size_t l = 0;
assert(in && out && key && ivec && num);
n = *num;
if (enc) {
#if !defined(OPENSSL_SMALL_FOOTPRINT)
if (16%sizeof(size_t) == 0) do { /* always true actually */
while (n && len) {
*(out++) = ivec[n] ^= *(in++);
--len;
n = (n+1) % 16;
}
#if defined(STRICT_ALIGNMENT)
if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
break;
#endif
while (len>=16) {
(*block)(ivec, ivec, key);
for (; n<16; n+=sizeof(size_t)) {
*(size_t*)(out+n) =
*(size_t*)(ivec+n) ^= *(size_t*)(in+n);
}
len -= 16;
out += 16;
in += 16;
n = 0;
}
if (len) {
(*block)(ivec, ivec, key);
while (len--) {
out[n] = ivec[n] ^= in[n];
++n;
}
}
*num = n;
return;
} while (0);
/* the rest would be commonly eliminated by x86* compiler */
#endif
while (l<len) {
if (n == 0) {
(*block)(ivec, ivec, key);
}
out[l] = ivec[n] ^= in[l];
++l;
n = (n+1) % 16;
}
*num = n;
} else {
#if !defined(OPENSSL_SMALL_FOOTPRINT)
if (16%sizeof(size_t) == 0) do { /* always true actually */
while (n && len) {
unsigned char c;
*(out++) = ivec[n] ^ (c = *(in++)); ivec[n] = c;
--len;
n = (n+1) % 16;
}
#if defined(STRICT_ALIGNMENT)
if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
break;
#endif
while (len>=16) {
(*block)(ivec, ivec, key);
for (; n<16; n+=sizeof(size_t)) {
size_t t = *(size_t*)(in+n);
*(size_t*)(out+n) = *(size_t*)(ivec+n) ^ t;
*(size_t*)(ivec+n) = t;
}
len -= 16;
out += 16;
in += 16;
n = 0;
}
if (len) {
(*block)(ivec, ivec, key);
while (len--) {
unsigned char c;
out[n] = ivec[n] ^ (c = in[n]); ivec[n] = c;
++n;
}
}
*num = n;
return;
} while (0);
/* the rest would be commonly eliminated by x86* compiler */
#endif
while (l<len) {
unsigned char c;
if (n == 0) {
(*block)(ivec, ivec, key);
}
out[l] = ivec[n] ^ (c = in[l]); ivec[n] = c;
++l;
n = (n+1) % 16;
}
*num=n;
}
}
/* This expects a single block of size nbits for both in and out. Note that
it corrupts any extra bits in the last byte of out */
static void cfbr_encrypt_block(const unsigned char *in,unsigned char *out,
int nbits,const void *key,
unsigned char ivec[16],int enc,
block128_f block)
{
int n,rem,num;
unsigned char ovec[16*2 + 1]; /* +1 because we dererefence (but don't use) one byte off the end */
if (nbits<=0 || nbits>128) return;
/* fill in the first half of the new IV with the current IV */
memcpy(ovec,ivec,16);
/* construct the new IV */
(*block)(ivec,ivec,key);
num = (nbits+7)/8;
if (enc) /* encrypt the input */
for(n=0 ; n < num ; ++n)
out[n] = (ovec[16+n] = in[n] ^ ivec[n]);
else /* decrypt the input */
for(n=0 ; n < num ; ++n)
out[n] = (ovec[16+n] = in[n]) ^ ivec[n];
/* shift ovec left... */
rem = nbits%8;
num = nbits/8;
if(rem==0)
memcpy(ivec,ovec+num,16);
else
for(n=0 ; n < 16 ; ++n)
ivec[n] = ovec[n+num]<<rem | ovec[n+num+1]>>(8-rem);
/* it is not necessary to cleanse ovec, since the IV is not secret */
}
/* N.B. This expects the input to be packed, MS bit first */
void CRYPTO_cfb128_1_encrypt(const unsigned char *in, unsigned char *out,
size_t bits, const void *key,
unsigned char ivec[16], int *num,
int enc, block128_f block)
{
size_t n;
unsigned char c[1],d[1];
assert(in && out && key && ivec && num);
assert(*num == 0);
for(n=0 ; n<bits ; ++n)
{
c[0]=(in[n/8]&(1 << (7-n%8))) ? 0x80 : 0;
cfbr_encrypt_block(c,d,1,key,ivec,enc,block);
out[n/8]=(out[n/8]&~(1 << (unsigned int)(7-n%8))) |
((d[0]&0x80) >> (unsigned int)(n%8));
}
}
void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
size_t length, const void *key,
unsigned char ivec[16], int *num,
int enc, block128_f block)
{
size_t n;
assert(in && out && key && ivec && num);
assert(*num == 0);
for(n=0 ; n<length ; ++n)
cfbr_encrypt_block(&in[n],&out[n],8,key,ivec,enc,block);
}