/* 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.

 */

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;

}