/*

 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (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

 */

#include "des_locl.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 DES_cfb64_encrypt(const unsigned char *in, unsigned char *out,

                       long length, DES_key_schedule *schedule,

                       DES_cblock *ivec, int *num, int enc)

{

    register DES_LONG v0, v1;

    register long l = length;

    register int n = *num;

    DES_LONG ti[2];

    unsigned char *iv, c, cc;

    iv = &(*ivec)[0];

    if (enc) {

        while (l--) {

            if (n == 0) {

                c2l(iv, v0);

                ti[0] = v0;

                c2l(iv, v1);

                ti[1] = v1;

                DES_encrypt1(ti, schedule, DES_ENCRYPT);

                iv = &(*ivec)[0];

                v0 = ti[0];

                l2c(v0, iv);

                v0 = ti[1];

                l2c(v0, iv);

                iv = &(*ivec)[0];

            }

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

            *(out++) = c;

            iv[n] = c;

            n = (n + 1) & 0x07;

        }

    } else {

        while (l--) {

            if (n == 0) {

                c2l(iv, v0);

                ti[0] = v0;

                c2l(iv, v1);

                ti[1] = v1;

                DES_encrypt1(ti, schedule, DES_ENCRYPT);

                iv = &(*ivec)[0];

                v0 = ti[0];

                l2c(v0, iv);

                v0 = ti[1];

                l2c(v0, iv);

                iv = &(*ivec)[0];

            }

            cc = *(in++);

            c = iv[n];

            iv[n] = cc;

            *(out++) = c ^ cc;

            n = (n + 1) & 0x07;

        }

    }

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

    *num = n;

}