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/*
Copyright (C) 2008 Luigi Auriemma
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
http://www.gnu.org/licenses/gpl-2.0.txt
*/
// Code modified by Luigi Auriemma. for emulating the shameful customizations of MagicISO
// Code derived from the reference implementation of J.S.A.Kapp with deep modifications.
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <time.h>
typedef uint32_t word32;
/* rotate functions */
#define ROTL(x,s) ((x)<<(s) | (x)>>(32-(s)))
#define ROTR(x,s) ((x)>>(s) | (x)<<(32-(s)))
/* Magic Contants */
#define P 0xb7e15163
#define Q 0x9e3779b9
#define ANDVAL 31
#define KR(x) (2*((x)+1))
#define MAX(x, y) (((x) > (y)) ? (x) : (y))
void RC5decrypt(word32 *in, int len, int b, word32 *key) {
int i;
int t;
for(t = b << 2; len; len--) {
key += t + 1;
for (i = 0; i < t; i += 2) {
in[1] -= *key--;
in[1] = ROTR(in[1], in[0]&ANDVAL) ^ in[0];
in[0] -= *key--;
in[0] ^= 0x63a72efb;
in[0] = ROTR(in[0], in[1]&ANDVAL) ^ in[1];
}
in[1] -= *key--;
in[0] -= *key;
in += 2;
}
}
void RC5key(unsigned char *key, int b, word32 **ctx) {
int t = (b << 2) + 2;
int i;
int x = ((b-1)/sizeof(word32))+1;
int mix = 3 * (MAX(t,x));
word32 *L, *ky;
word32 A = 0, B = 0;
L = (word32 *) calloc((x+1), sizeof(word32));
memcpy((unsigned char *)L, key, b);
ky = (word32 *) calloc((t+1), sizeof(word32));
*ky = P;
/* Prep subkeys with magic Constants */
for(i = 1; i < t; i++)
ky[i] = ky[i-1] + Q;
for(i = 0; i < mix; i++) {
A = ky[i%t] = ROTL((ky[i%t] + A + B), 3&ANDVAL);
B = L[i%x] = ROTL((L[i%x] + A + B), ((A + B)&ANDVAL));
}
free(L);
*ctx = ky;
}
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