/* crypto/des/ofb_enc.c */

 /* 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.]

  */

 #include "des_locl.h"

 /* The input and output are loaded in multiples of 8 bits.

  * What this means is that if you hame numbits=12 and length=2

  * the first 12 bits will be retrieved from the first byte and half

  * the second.  The second 12 bits will come from the 3rd and half the 4th

  * byte.

  */

 EXPORT_C void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits,

 		     long length, DES_key_schedule *schedule,

 		     DES_cblock *ivec)

 	{

 	register DES_LONG d0,d1,vv0,vv1,v0,v1,n=(numbits+7)/8;

 	register DES_LONG mask0,mask1;

 	register long l=length;

 	register int num=numbits;

 	DES_LONG ti[2];

 	unsigned char *iv;

 	if (num > 64) return;

 	if (num > 32)

 		{

 		mask0=0xffffffffL;

 		if (num >= 64)

 			mask1=mask0;

 		else

 			mask1=(1L<<(num-32))-1;

 		}

 	else

 		{

 		if (num == 32)

 			mask0=0xffffffffL;

 		else

 			mask0=(1L<<num)-1;

 		mask1=0x00000000L;

 		}

 	iv = &(*ivec)[0];

 	c2l(iv,v0);

 	c2l(iv,v1);

 	ti[0]=v0;

 	ti[1]=v1;

 	while (l-- > 0)

 		{

 		ti[0]=v0;

 		ti[1]=v1;

 		DES_encrypt1((DES_LONG *)ti,schedule,DES_ENCRYPT);

 		vv0=ti[0];

 		vv1=ti[1];

 		c2ln(in,d0,d1,n);

 		in+=n;

 		d0=(d0^vv0)&mask0;

 		d1=(d1^vv1)&mask1;

 		l2cn(d0,d1,out,n);

 		out+=n;

 		if (num == 32)

 			{ v0=v1; v1=vv0; }

 		else if (num == 64)

 				{ v0=vv0; v1=vv1; }

 		else if (num > 32) /* && num != 64 */

 			{

 			v0=((v1>>(num-32))|(vv0<<(64-num)))&0xffffffffL;

 			v1=((vv0>>(num-32))|(vv1<<(64-num)))&0xffffffffL;

 			}

 		else /* num < 32 */

 			{

 			v0=((v0>>num)|(v1<<(32-num)))&0xffffffffL;

 			v1=((v1>>num)|(vv0<<(32-num)))&0xffffffffL;

 			}

 		}

 	iv = &(*ivec)[0];

 	l2c(v0,iv);

 	l2c(v1,iv);

 	v0=v1=d0=d1=ti[0]=ti[1]=vv0=vv1=0;

 	}