/*

 * Copyright 1995-2022 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

/*

 * DES low level APIs are deprecated for public use, but still ok for internal

 * use.

 */

#include "internal/deprecated.h"

#include "internal/e_os.h"

#include "des_local.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 assertion, */

    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;

}