/*

 * 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 <openssl/idea.h>

#include "idea_local.h"

static IDEA_INT inverse(unsigned int xin);

void IDEA_set_encrypt_key(const unsigned char *key, IDEA_KEY_SCHEDULE *ks)

{

    int i;

    register IDEA_INT *kt, *kf, r0, r1, r2;

    kt = &(ks->data[0][0]);

    n2s(key, kt[0]);

    n2s(key, kt[1]);

    n2s(key, kt[2]);

    n2s(key, kt[3]);

    n2s(key, kt[4]);

    n2s(key, kt[5]);

    n2s(key, kt[6]);

    n2s(key, kt[7]);

    kf = kt;

    kt += 8;

    for (i = 0; i < 6; i++) {

        r2 = kf[1];

        r1 = kf[2];

        *(kt++) = ((r2 << 9) | (r1 >> 7)) & 0xffff;

        r0 = kf[3];

        *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;

        r1 = kf[4];

        *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;

        r0 = kf[5];

        *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;

        r1 = kf[6];

        *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;

        r0 = kf[7];

        *(kt++) = ((r1 << 9) | (r0 >> 7)) & 0xffff;

        r1 = kf[0];

        if (i >= 5)

            break;

        *(kt++) = ((r0 << 9) | (r1 >> 7)) & 0xffff;

        *(kt++) = ((r1 << 9) | (r2 >> 7)) & 0xffff;

        kf += 8;

    }

}

void IDEA_set_decrypt_key(IDEA_KEY_SCHEDULE *ek, IDEA_KEY_SCHEDULE *dk)

{

    int r;

    register IDEA_INT *fp, *tp, t;

    tp = &(dk->data[0][0]);

    fp = &(ek->data[8][0]);

    for (r = 0; r < 9; r++) {

        *(tp++) = inverse(fp[0]);

        *(tp++) = ((int)(0x10000L - fp[2]) & 0xffff);

        *(tp++) = ((int)(0x10000L - fp[1]) & 0xffff);

        *(tp++) = inverse(fp[3]);

        if (r == 8)

            break;

        fp -= 6;

        *(tp++) = fp[4];

        *(tp++) = fp[5];

    }

    tp = &(dk->data[0][0]);

    t = tp[1];

    tp[1] = tp[2];

    tp[2] = t;

    t = tp[49];

    tp[49] = tp[50];

    tp[50] = t;

}

/* taken directly from the 'paper' I'll have a look at it later */

static IDEA_INT inverse(unsigned int xin)

{

    long n1, n2, q, r, b1, b2, t;

    if (xin == 0)

        b2 = 0;

    else {

        n1 = 0x10001;

        n2 = xin;

        b2 = 1;

        b1 = 0;

        do {

            r = (n1 % n2);

            q = (n1 - r) / n2;

            if (r == 0) {

                if (b2 < 0)

                    b2 = 0x10001 + b2;

            } else {

                n1 = n2;

                n2 = r;

                t = b2;

                b2 = b1 - q * b2;

                b1 = t;

            }

        } while (r != 0);

    }

    return (IDEA_INT)b2;

}