252 lines
7.5 KiB
C
252 lines
7.5 KiB
C
/* crypto/aes/aes_cfb.c -*- mode:C; c-file-style: "eay" -*- */
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/* ====================================================================
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* Copyright (c) 2002-2006 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* openssl-core@openssl.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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* ====================================================================
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*
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*/
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#ifndef AES_DEBUG
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# ifndef NDEBUG
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# define NDEBUG
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# endif
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#endif
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#include <assert.h>
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#include <openssl/aes.h>
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#include "aes_locl.h"
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#include "e_os.h"
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#define STRICT_ALIGNMENT
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#if defined(__i386) || defined(__i386__) || \
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defined(__x86_64) || defined(__x86_64__) || \
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defined(_M_IX86) || defined(_M_AMD64) || defined(_M_X64)
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# undef STRICT_ALIGNMENT
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#endif
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/* The input and output encrypted as though 128bit cfb mode is being
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* used. The extra state information to record how much of the
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* 128bit block we have used is contained in *num;
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*/
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void AES_cfb128_encrypt(const unsigned char *in, unsigned char *out,
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unsigned long length, const AES_KEY *key,
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unsigned char *ivec, int *num, const int enc) {
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unsigned int n;
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unsigned long l = 0;
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assert(in && out && key && ivec && num);
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n = *num;
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#if !defined(OPENSSL_SMALL_FOOTPRINT)
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if (AES_BLOCK_SIZE%sizeof(size_t) == 0) { /* always true actually */
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if (enc) {
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if (n) {
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while (length) {
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*(out++) = ivec[n] ^= *(in++);
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length--;
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if(!(n = (n + 1) % AES_BLOCK_SIZE))
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break;
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}
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}
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#if defined(STRICT_ALIGNMENT)
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if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
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goto enc_unaligned;
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#endif
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while ((l + AES_BLOCK_SIZE) <= length) {
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unsigned int i;
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AES_encrypt(ivec, ivec, key);
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for (i=0;i<AES_BLOCK_SIZE;i+=sizeof(size_t)) {
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*(size_t*)(out+l+i) =
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*(size_t*)(ivec+i) ^= *(size_t*)(in+l+i);
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}
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l += AES_BLOCK_SIZE;
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}
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if (l < length) {
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AES_encrypt(ivec, ivec, key);
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do { out[l] = ivec[n] ^= in[l];
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l++; n++;
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} while (l < length);
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}
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} else {
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if (n) {
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while (length) {
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unsigned char c;
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*(out++) = ivec[n] ^ (c = *(in++)); ivec[n] = c;
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length--;
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if(!(n = (n + 1) % AES_BLOCK_SIZE))
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break;
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}
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}
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#if defined(STRICT_ALIGNMENT)
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if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
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goto dec_unaligned;
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#endif
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while (l + AES_BLOCK_SIZE <= length) {
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unsigned int i;
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AES_encrypt(ivec, ivec, key);
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for (i=0;i<AES_BLOCK_SIZE;i+=sizeof(size_t)) {
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size_t t = *(size_t*)(in+l+i);
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*(size_t*)(out+l+i) = *(size_t*)(ivec+i) ^ t;
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*(size_t*)(ivec+i) = t;
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}
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l += AES_BLOCK_SIZE;
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}
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if (l < length) {
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AES_encrypt(ivec, ivec, key);
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do { unsigned char c;
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out[l] = ivec[n] ^ (c = in[l]); ivec[n] = c;
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l++; n++;
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} while (l < length);
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}
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}
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*num = n;
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return;
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}
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#endif
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/* this code would be commonly eliminated by x86* compiler */
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if (enc) {
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#if defined(STRICT_ALIGNMENT) && !defined(OPENSSL_SMALL_FOOTPRINT)
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enc_unaligned:
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#endif
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while (l<length) {
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if (n == 0) {
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AES_encrypt(ivec, ivec, key);
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}
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out[l] = ivec[n] ^= in[l];
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l++;
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n = (n+1) % AES_BLOCK_SIZE;
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}
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} else {
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#if defined(STRICT_ALIGNMENT) && !defined(OPENSSL_SMALL_FOOTPRINT)
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dec_unaligned:
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#endif
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while (l<length) {
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unsigned char c;
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if (n == 0) {
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AES_encrypt(ivec, ivec, key);
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}
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out[l] = ivec[n] ^ (c = in[l]); ivec[n] = c;
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l++;
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n = (n+1) % AES_BLOCK_SIZE;
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}
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}
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*num=n;
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}
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/* This expects a single block of size nbits for both in and out. Note that
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it corrupts any extra bits in the last byte of out */
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void AES_cfbr_encrypt_block(const unsigned char *in,unsigned char *out,
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const int nbits,const AES_KEY *key,
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unsigned char *ivec,const int enc)
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{
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int n,rem,num;
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unsigned char ovec[AES_BLOCK_SIZE*2 + 1]; /* +1 because we dererefence (but don't use) one byte off the end */
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if (nbits<=0 || nbits>128) return;
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/* fill in the first half of the new IV with the current IV */
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memcpy(ovec,ivec,AES_BLOCK_SIZE);
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/* construct the new IV */
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AES_encrypt(ivec,ivec,key);
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num = (nbits+7)/8;
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if (enc) /* encrypt the input */
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for(n=0 ; n < num ; ++n)
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out[n] = (ovec[AES_BLOCK_SIZE+n] = in[n] ^ ivec[n]);
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else /* decrypt the input */
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for(n=0 ; n < num ; ++n)
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out[n] = (ovec[AES_BLOCK_SIZE+n] = in[n]) ^ ivec[n];
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/* shift ovec left... */
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rem = nbits%8;
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num = nbits/8;
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if(rem==0)
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memcpy(ivec,ovec+num,AES_BLOCK_SIZE);
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else
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for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
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ivec[n] = ovec[n+num]<<rem | ovec[n+num+1]>>(8-rem);
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/* it is not necessary to cleanse ovec, since the IV is not secret */
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}
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/* N.B. This expects the input to be packed, MS bit first */
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void AES_cfb1_encrypt(const unsigned char *in, unsigned char *out,
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const unsigned long length, const AES_KEY *key,
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unsigned char *ivec, int *num, const int enc)
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{
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unsigned int n;
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unsigned char c[1],d[1];
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assert(in && out && key && ivec && num);
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assert(*num == 0);
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memset(out,0,(length+7)/8);
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for(n=0 ; n < length ; ++n)
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{
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c[0]=(in[n/8]&(1 << (7-n%8))) ? 0x80 : 0;
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AES_cfbr_encrypt_block(c,d,1,key,ivec,enc);
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out[n/8]=(out[n/8]&~(1 << (7-n%8)))|((d[0]&0x80) >> (n%8));
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}
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}
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void AES_cfb8_encrypt(const unsigned char *in, unsigned char *out,
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const unsigned long length, const AES_KEY *key,
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unsigned char *ivec, int *num, const int enc)
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{
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unsigned int n;
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assert(in && out && key && ivec && num);
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assert(*num == 0);
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for(n=0 ; n < length ; ++n)
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AES_cfbr_encrypt_block(&in[n],&out[n],8,key,ivec,enc);
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}
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