crypto/cast/c_skey.c

/*
 * Copyright 1995-2020 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
 */

/*
 * CAST low level APIs are deprecated for public use, but still ok for
 * internal use.
 */
#include "internal/deprecated.h"

#include <openssl/cast.h>
#include "cast_local.h"
#include "cast_s.h"

#define CAST_exp(l,A,a,n) \
        A[n/4]=l; \
        a[n+3]=(l    )&0xff; \
        a[n+2]=(l>> 8)&0xff; \
        a[n+1]=(l>>16)&0xff; \
        a[n+0]=(l>>24)&0xff;

#define S4 CAST_S_table4
#define S5 CAST_S_table5
#define S6 CAST_S_table6
#define S7 CAST_S_table7

void CAST_set_key(CAST_KEY *key, int len, const unsigned char *data)
{
    CAST_LONG x[16];
    CAST_LONG z[16];
    CAST_LONG k[32];
    CAST_LONG X[4], Z[4];
    CAST_LONG l, *K;
    int i;

    for (i = 0; i < 16; i++)
        x[i] = 0;
    if (len > 16)
        len = 16;
    for (i = 0; i < len; i++)
        x[i] = data[i];
    if (len <= 10)
        key->short_key = 1;
    else
        key->short_key = 0;

    K = &k[0];
    X[0] = ((x[0] << 24) | (x[1] << 16) | (x[2] << 8) | x[3]) & 0xffffffffL;
    X[1] = ((x[4] << 24) | (x[5] << 16) | (x[6] << 8) | x[7]) & 0xffffffffL;
    X[2] = ((x[8] << 24) | (x[9] << 16) | (x[10] << 8) | x[11]) & 0xffffffffL;
    X[3] =
        ((x[12] << 24) | (x[13] << 16) | (x[14] << 8) | x[15]) & 0xffffffffL;

    for (;;) {
        l = X[0] ^ S4[x[13]] ^ S5[x[15]] ^ S6[x[12]] ^ S7[x[14]] ^ S6[x[8]];
        CAST_exp(l, Z, z, 0);
        l = X[2] ^ S4[z[0]] ^ S5[z[2]] ^ S6[z[1]] ^ S7[z[3]] ^ S7[x[10]];
        CAST_exp(l, Z, z, 4);
        l = X[3] ^ S4[z[7]] ^ S5[z[6]] ^ S6[z[5]] ^ S7[z[4]] ^ S4[x[9]];
        CAST_exp(l, Z, z, 8);
        l = X[1] ^ S4[z[10]] ^ S5[z[9]] ^ S6[z[11]] ^ S7[z[8]] ^ S5[x[11]];
        CAST_exp(l, Z, z, 12);

        K[0] = S4[z[8]] ^ S5[z[9]] ^ S6[z[7]] ^ S7[z[6]] ^ S4[z[2]];
        K[1] = S4[z[10]] ^ S5[z[11]] ^ S6[z[5]] ^ S7[z[4]] ^ S5[z[6]];
        K[2] = S4[z[12]] ^ S5[z[13]] ^ S6[z[3]] ^ S7[z[2]] ^ S6[z[9]];
        K[3] = S4[z[14]] ^ S5[z[15]] ^ S6[z[1]] ^ S7[z[0]] ^ S7[z[12]];

        l = Z[2] ^ S4[z[5]] ^ S5[z[7]] ^ S6[z[4]] ^ S7[z[6]] ^ S6[z[0]];
        CAST_exp(l, X, x, 0);
        l = Z[0] ^ S4[x[0]] ^ S5[x[2]] ^ S6[x[1]] ^ S7[x[3]] ^ S7[z[2]];
        CAST_exp(l, X, x, 4);
        l = Z[1] ^ S4[x[7]] ^ S5[x[6]] ^ S6[x[5]] ^ S7[x[4]] ^ S4[z[1]];
        CAST_exp(l, X, x, 8);
        l = Z[3] ^ S4[x[10]] ^ S5[x[9]] ^ S6[x[11]] ^ S7[x[8]] ^ S5[z[3]];
        CAST_exp(l, X, x, 12);

        K[4] = S4[x[3]] ^ S5[x[2]] ^ S6[x[12]] ^ S7[x[13]] ^ S4[x[8]];
        K[5] = S4[x[1]] ^ S5[x[0]] ^ S6[x[14]] ^ S7[x[15]] ^ S5[x[13]];
        K[6] = S4[x[7]] ^ S5[x[6]] ^ S6[x[8]] ^ S7[x[9]] ^ S6[x[3]];
        K[7] = S4[x[5]] ^ S5[x[4]] ^ S6[x[10]] ^ S7[x[11]] ^ S7[x[7]];

        l = X[0] ^ S4[x[13]] ^ S5[x[15]] ^ S6[x[12]] ^ S7[x[14]] ^ S6[x[8]];
        CAST_exp(l, Z, z, 0);
        l = X[2] ^ S4[z[0]] ^ S5[z[2]] ^ S6[z[1]] ^ S7[z[3]] ^ S7[x[10]];
        CAST_exp(l, Z, z, 4);
        l = X[3] ^ S4[z[7]] ^ S5[z[6]] ^ S6[z[5]] ^ S7[z[4]] ^ S4[x[9]];
        CAST_exp(l, Z, z, 8);
        l = X[1] ^ S4[z[10]] ^ S5[z[9]] ^ S6[z[11]] ^ S7[z[8]] ^ S5[x[11]];
        CAST_exp(l, Z, z, 12);

        K[8] = S4[z[3]] ^ S5[z[2]] ^ S6[z[12]] ^ S7[z[13]] ^ S4[z[9]];
        K[9] = S4[z[1]] ^ S5[z[0]] ^ S6[z[14]] ^ S7[z[15]] ^ S5[z[12]];
        K[10] = S4[z[7]] ^ S5[z[6]] ^ S6[z[8]] ^ S7[z[9]] ^ S6[z[2]];
        K[11] = S4[z[5]] ^ S5[z[4]] ^ S6[z[10]] ^ S7[z[11]] ^ S7[z[6]];

        l = Z[2] ^ S4[z[5]] ^ S5[z[7]] ^ S6[z[4]] ^ S7[z[6]] ^ S6[z[0]];
        CAST_exp(l, X, x, 0);
        l = Z[0] ^ S4[x[0]] ^ S5[x[2]] ^ S6[x[1]] ^ S7[x[3]] ^ S7[z[2]];
        CAST_exp(l, X, x, 4);
        l = Z[1] ^ S4[x[7]] ^ S5[x[6]] ^ S6[x[5]] ^ S7[x[4]] ^ S4[z[1]];
        CAST_exp(l, X, x, 8);
        l = Z[3] ^ S4[x[10]] ^ S5[x[9]] ^ S6[x[11]] ^ S7[x[8]] ^ S5[z[3]];
        CAST_exp(l, X, x, 12);

        K[12] = S4[x[8]] ^ S5[x[9]] ^ S6[x[7]] ^ S7[x[6]] ^ S4[x[3]];
        K[13] = S4[x[10]] ^ S5[x[11]] ^ S6[x[5]] ^ S7[x[4]] ^ S5[x[7]];
        K[14] = S4[x[12]] ^ S5[x[13]] ^ S6[x[3]] ^ S7[x[2]] ^ S6[x[8]];
        K[15] = S4[x[14]] ^ S5[x[15]] ^ S6[x[1]] ^ S7[x[0]] ^ S7[x[13]];
        if (K != k)
            break;
        K += 16;
    }

    for (i = 0; i < 16; i++) {
        key->data[i * 2] = k[i];
        key->data[i * 2 + 1] = ((k[i + 16]) + 16) & 0x1f;
    }
}