aes_cfb.c
/* crypto/aes/aes_cfb.c -*- mode:C; c-file-style: "eay" -*- */
/* ====================================================================
* Copyright (c) 1998-2002 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
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* 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/)"
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* 5. Products derived from this software may not be called "OpenSSL"
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* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* 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 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 acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS 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 AUTHOR OR 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.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
#ifndef AES_DEBUG
# ifndef NDEBUG
# define NDEBUG
# endif
#endif
#include <assert.h>
#include <openssl/aes.h>
#include "aes_locl.h"
#include "e_os.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 AES_cfb128_encrypt(const unsigned char *in, unsigned char *out,
const unsigned long length, const AES_KEY *key,
unsigned char *ivec, int *num, const int enc)
{
unsigned int n;
unsigned long l = length;
unsigned char c;
assert(in && out && key && ivec && num);
n = *num;
if (enc) {
while (l--) {
if (n == 0) {
AES_encrypt(ivec, ivec, key);
}
ivec[n] = *(out++) = *(in++) ^ ivec[n];
n = (n + 1) % AES_BLOCK_SIZE;
}
} else {
while (l--) {
if (n == 0) {
AES_encrypt(ivec, ivec, key);
}
c = *(in);
*(out++) = *(in++) ^ ivec[n];
ivec[n] = c;
n = (n + 1) % AES_BLOCK_SIZE;
}
}
*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
*/
void AES_cfbr_encrypt_block(const unsigned char *in, unsigned char *out,
const int nbits, const AES_KEY *key,
unsigned char *ivec, const int enc)
{
int n, rem, num;
unsigned char ovec[AES_BLOCK_SIZE * 2];
if (nbits <= 0 || nbits > 128)
return;
/* fill in the first half of the new IV with the current IV */
memcpy(ovec, ivec, AES_BLOCK_SIZE);
/* construct the new IV */
AES_encrypt(ivec, ivec, key);
num = (nbits + 7) / 8;
if (enc) /* encrypt the input */
for (n = 0; n < num; ++n)
out[n] = (ovec[AES_BLOCK_SIZE + n] = in[n] ^ ivec[n]);
else /* decrypt the input */
for (n = 0; n < num; ++n)
out[n] = (ovec[AES_BLOCK_SIZE + n] = in[n]) ^ ivec[n];
/* shift ovec left... */
rem = nbits % 8;
num = nbits / 8;
if (rem == 0)
memcpy(ivec, ovec + num, AES_BLOCK_SIZE);
else
for (n = 0; n < AES_BLOCK_SIZE; ++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 AES_cfb1_encrypt(const unsigned char *in, unsigned char *out,
const unsigned long length, const AES_KEY *key,
unsigned char *ivec, int *num, const int enc)
{
unsigned int n;
unsigned char c[1], d[1];
assert(in && out && key && ivec && num);
assert(*num == 0);
for (n = 0; n < length; ++n) {
c[0] = (in[n / 8] & (1 << (7 - n % 8))) ? 0x80 : 0;
AES_cfbr_encrypt_block(c, d, 1, key, ivec, enc);
out[n / 8] =
(out[n / 8] & ~(1 << (7 - n % 8))) | ((d[0] & 0x80) >> (n % 8));
}
}
void AES_cfb8_encrypt(const unsigned char *in, unsigned char *out,
const unsigned long length, const AES_KEY *key,
unsigned char *ivec, int *num, const int enc)
{
unsigned int n;
assert(in && out && key && ivec && num);
assert(*num == 0);
for (n = 0; n < length; ++n)
AES_cfbr_encrypt_block(&in[n], &out[n], 8, key, ivec, enc);
}
