/* $OpenBSD: c_cfb64.c,v 1.5 2014/10/28 07:35:58 jsg Exp $ */

/* 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 <openssl/cast.h>

#include "cast_lcl.h"

/* The input and output encrypted as though 64bit cfb mode is being

 * used.  The extra state information to record how much of the

 * 64bit block we have used is contained in *num;

 */

void CAST_cfb64_encrypt(const unsigned char *in, unsigned char *out,

      long length, const CAST_KEY *schedule, unsigned char *ivec,

      int *num, int enc)

  {

  CAST_LONG v0,v1,t;

  int n= *num;

  long l=length;

  CAST_LONG ti[2];

  unsigned char *iv,c,cc;

  iv=ivec;

  if (enc)

    {

    while (l--)

      {

      if (n == 0)

        {

        n2l(iv,v0); ti[0]=v0;

        n2l(iv,v1); ti[1]=v1;

        CAST_encrypt((CAST_LONG *)ti,schedule);

        iv=ivec;

        t=ti[0]; l2n(t,iv);

        t=ti[1]; l2n(t,iv);

        iv=ivec;

        }

      c= *(in++)^iv[n];

      *(out++)=c;

      iv[n]=c;

      n=(n+1)&0x07;

      }

    }

  else

    {

    while (l--)

      {

      if (n == 0)

        {

        n2l(iv,v0); ti[0]=v0;

        n2l(iv,v1); ti[1]=v1;

        CAST_encrypt((CAST_LONG *)ti,schedule);

        iv=ivec;

        t=ti[0]; l2n(t,iv);

        t=ti[1]; l2n(t,iv);

        iv=ivec;

        }

      cc= *(in++);

      c=iv[n];

      iv[n]=cc;

      *(out++)=c^cc;

      n=(n+1)&0x07;

      }

    }

  v0=v1=ti[0]=ti[1]=t=c=cc=0;

  *num=n;

  }