i_skey.c
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/*
* 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_lcl.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;
}