/* crypto/des/cfb_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 "e_os.h"

 #include "des_locl.h"

 #include <assert.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.

  */

 /* Until Aug 1 2003 this function did not correctly implement CFB-r, so it

  * will not be compatible with any encryption prior to that date. Ben. */

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

 		     long length, DES_key_schedule *schedule, DES_cblock *ivec,

 		     int enc)

 	{

 	register DES_LONG d0,d1,v0,v1;

 	register unsigned long l=length;

 	register int num=numbits/8,n=(numbits+7)/8,i,rem=numbits%8;

 	DES_LONG ti[2];

 	unsigned char *iv;

 #ifndef L_ENDIAN

 	unsigned char ovec[16];

 #else

 	unsigned int  sh[4];

 	unsigned char *ovec=(unsigned char *)sh;

 	/* I kind of count that compiler optimizes away this assertioni,*/

 	assert (sizeof(sh[0])==4);	/* as this holds true for all,	*/

 					/* but 16-bit platforms...	*/

 #endif

 	if (numbits<=0 || numbits > 64) return;

 	iv = &(*ivec)[0];

 	c2l(iv,v0);

 	c2l(iv,v1);

 	if (enc)

 		{

 		while (l >= (unsigned long)n)

 			{

 			l-=n;

 			ti[0]=v0;

 			ti[1]=v1;

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

 			c2ln(in,d0,d1,n);

 			in+=n;

 			d0^=ti[0];

 			d1^=ti[1];

 			l2cn(d0,d1,out,n);

 			out+=n;

 			/* 30-08-94 - eay - changed because l>>32 and

 			 * l<<32 are bad under gcc :-( */

 			if (numbits == 32)

 				{ v0=v1; v1=d0; }

 			else if (numbits == 64)

 				{ v0=d0; v1=d1; }

 			else

 				{

 #ifndef L_ENDIAN

 				iv=&ovec[0];

 				l2c(v0,iv);

 				l2c(v1,iv);

 				l2c(d0,iv);

 				l2c(d1,iv);

 #else

 				sh[0]=v0, sh[1]=v1, sh[2]=d0, sh[3]=d1;

 #endif

 				if (rem==0)

 					memmove(ovec,ovec+num,8);

 				else

 					for(i=0 ; i < 8 ; ++i)

 						ovec[i]=ovec[i+num]<<rem |

 							ovec[i+num+1]>>(8-rem);

 #ifdef L_ENDIAN

 				v0=sh[0], v1=sh[1];

 #else

 				iv=&ovec[0];

 				c2l(iv,v0);

 				c2l(iv,v1);

 #endif

 				}

 			}

 		}

 	else

 		{

 		while (l >= (unsigned long)n)

 			{

 			l-=n;

 			ti[0]=v0;

 			ti[1]=v1;

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

 			c2ln(in,d0,d1,n);

 			in+=n;

 			/* 30-08-94 - eay - changed because l>>32 and

 			 * l<<32 are bad under gcc :-( */

 			if (numbits == 32)

 				{ v0=v1; v1=d0; }

 			else if (numbits == 64)

 				{ v0=d0; v1=d1; }

 			else

 				{

 #ifndef L_ENDIAN

 				iv=&ovec[0];

 				l2c(v0,iv);

 				l2c(v1,iv);

 				l2c(d0,iv);

 				l2c(d1,iv);

 #else

 				sh[0]=v0, sh[1]=v1, sh[2]=d0, sh[3]=d1;

 #endif

 				if (rem==0)

 					memmove(ovec,ovec+num,8);

 				else

 					for(i=0 ; i < 8 ; ++i)

 						ovec[i]=ovec[i+num]<<rem |

 							ovec[i+num+1]>>(8-rem);

 #ifdef L_ENDIAN

 				v0=sh[0], v1=sh[1];

 #else

 				iv=&ovec[0];

 				c2l(iv,v0);

 				c2l(iv,v1);

 #endif

 				}

 			d0^=ti[0];

 			d1^=ti[1];

 			l2cn(d0,d1,out,n);

 			out+=n;

 			}

 		}

 	iv = &(*ivec)[0];

 	l2c(v0,iv);

 	l2c(v1,iv);

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

 	}