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/******
gcdkeyc.c
GameSpy CDKey SDK Client Code
Copyright 1999-2007 GameSpy Industries, Inc
devsupport@gamespy.com
******
Please see the GameSpy CDKey SDK documentation for more
information
******/
#include "../md5.h"
#include "gcdkeyc.h"
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define RAWSIZE 512
#ifdef __cplusplus
extern "C" {
#endif
// method = 0 for normal auth response from game server
// method = 1 for reauth response originating from keymaster
void gcd_compute_response(char *cdkey, char *challenge, char response[RESPONSE_SIZE], CDResponseMethod method)
{
char rawout[RAWSIZE];
unsigned int anyrandom;
char randstr[9];
/* check to make sure we weren't passed a huge cd key/challenge */
if (strlen(cdkey) * 2 + strlen(challenge) + 8 >= RAWSIZE)
{
strcpy(response,"CD Key or challenge too long");
return;
}
/* make sure we are randomized */
srand((unsigned int)time(NULL) ^ 0x33333333);
/* Since RAND_MAX is 16 bit on many systems, make sure we get a 32 bit number */
anyrandom = (rand() << 16 | rand());
sprintf(randstr,"%.8x",anyrandom);
/* auth response = MD5(cdkey + random mod 0xffff + challenge) */
/* reauth response = MD5(challenge + random mode 0xffff + cdkey) */
if (method == 0)
sprintf(rawout, "%s%d%s",cdkey, anyrandom % 0xFFFF , challenge );
else
sprintf(rawout, "%s%d%s",challenge, anyrandom % 0xFFFF, cdkey);
/* do the cd key md5 */
MD5Digest((unsigned char *)cdkey, strlen(cdkey), response);
/* add the random value */
strcpy(&response[32], randstr);
/* do the response md5 */
MD5Digest((unsigned char *)rawout, strlen(rawout), &response[40]);
}
#ifdef __cplusplus
}
#endif
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