/* 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.

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 * 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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 *    acknowledgment:

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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;

 */

EXPORT_C 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 */

EXPORT_C 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 */

EXPORT_C 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);

    memset(out,0,(length+7)/8);

    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));

	}

    }

EXPORT_C 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);

    }