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L'angolo della cultura |
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L'angolo della cultura |
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Microsoft CD Key Validation Explained
With the rush in of Windows'95, Microsoft has implemented a CD Key to help foil piracy and possibly regional tracking of software. With the CD Key in place, it makes it a PURE hassle cause if you're like me, I misplace my CD cases or one of my kids eats the sticker. Also HOW does this stop piracy? Here is an example, someone comes over and copies your Windows'95 CD and the KEY. Now that's really a solution. This document will cover details about the Microsoft CD Keys and how a CD Key is validated. C Source code will be provided to show how a key can be generated (written in Borland C++ 3.1).
The first 3 digits of the CD Key are garbage. They bear no value to the authentication of the key itself. Perhaps its a manufacturing or regional code. If you know what the first 3 digits mean, please email me at mindrape@goodnet.com
Example: XXX-0123456
|_| |_____|
| |
Garbage |
Key
Example: XXXXX-OEM-0123456-XXXXX
|_______| |_____| |___|
| | |
| Key |
|_______________|
|
|
Garbage
The algorythm to the validation routine is a VERY simple one. One can write a small amount of source code that will randomly generate valid CD Keys.
Lets use the following key as an example: 666-0077700 (Lucky 7's Key)
0 + 0 + 7 + 7 + 7 + 0 + 0 = 21
21 / 7 = 3.0
The source code included has been tested and verified. It requires no special parameters to compile.
> Cut here - FileName CDKey.c
/*
This source code contains a authentication routine that will
validate Microsoft CD Keys. It is meant that this source code
is a learning tool and not a PIRACY tool. It is also meant to
show how a large corporation like Microsoft spend MILLIONS of
dollars on development and come up with this protection scheme.
*BorlandC 3.1 was used to compile this successfully.
It is a crime to redistribute these routines in a commercial
venture of any kind without permission or licensing agreement.
C)opyright 1995 Damaged Cybernetics
If you have any questions or comments, please contact the
following ppl via the Internet:
Donald Moore (MindRape) mind@goodnet.com
Donald Staheli (Royce) staheli@goodnet.com
Web Page: www.goodnet.com/%7Estaheli
*/
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
/* Prototypes */
void help(void);
char ValidateCDKey(char *szKey);
/* definitions for ValidateCDKey function */
#define VALID_KEY 1 /* Yes this is a valid key */
#define INVALID_KEY 0 /* No this is not a valid key */
#define INVALID_CHAR -1 /* This key contains invalid characters */
#define INVALID_LENGTH -2 /* This key is the incorrect length */
/* Length of a Microsoft CD Key, this include the hyphen! */
#define MS_CD_KEY_LENGTH 11 /* XXX-0123456 */
#define OEM_CD_KEY_LENGTH 23 /* XXXXX-OEM-0123456-XXXXX */
#define REAL_KEY_LENGTH 7 /* length of the key is really 7 chars! */
#define REAL_MS_OFFSET 4 /* The MS CD REAL Key offset */
#define REAL_OEM_OFFSET 10 /* The OEM CD Real Key offset */
/*
char ValidateCDKey(char *szKey)
ENT: szKey - Char - Key to validate
RET: VALID_KEY - The key is valid
INVALID_KEY - The key is invalid
INVALID_LENGTH - The key is not a valid CD Key length
INVALID_CHAR - The key contains invalid characters
ValidateCDKey will take either a Microsoft or a Microsoft OEM CD Key
and verify of it's a authentic CD Key which can be used to unlock their
software when installing.
*/
char ValidateCDKey (char *szKey)
{
unsigned long ulCheckSum = 0L; /* Hold our checksum value here */
int iStrLength; /* Length of the CD Key */
int i = 0; /* dummy counter */
iStrLength = strlen(szKey);
/* is the key the correct length? */
if (iStrLength != MS_CD_KEY_LENGTH && iStrLength != OEM_CD_KEY_LENGTH)
return INVALID_LENGTH;
/* now move the pointer to the start of the REAL key */
szKey += iStrLength == MS_CD_KEY_LENGTH ? REAL_MS_OFFSET :
REAL_OEM_OFFSET;
/* now loop thru the CD Key, adding each digit to each other
* and then mod it by 7. If it's 0 we have a valid key!
*
* btw this routine can be optimized! It is written for sake of
* clairity.
*/
while (i < REAL_KEY_LENGTH)
{
if (isdigit(*szKey))
{
/* convert each char to it's actual decimal value by
* subtracting 48 and keep accumlating the values
*/
ulCheckSum += ((int) *szKey - 48);
}
else
return INVALID_CHAR; /* we hit a NON numeric character */
szKey++;
i++;
}
if (!(ulCheckSum % 7))
return VALID_KEY; /* This IS a valid Microsoft CD Key */
return INVALID_KEY; /* This IS NOT a valid Microsoft CD Key */
}
void help(void)
{
printf("This program will verify whether the CD Key you are using is a\n"
"a valid Microsoft CD Key. It is not meant to endorse PIRACY, but\n"
"to show a big company like Microsoft who has spent millions of\n"
"dollars and came up with this routine.\n"
"\nUsage: CDKey \n"
" i.e. Microsoft CD Key - CDKey 012-0123456\n"
" i.e. OEM CD Key - CDKey 01234-OEM-012345-01234\n"
);
exit(0);
}
void main(int argc,char *argv[])
{
puts("Microsoft CD Key Validation\n(C) 1995 Damaged Cybernetics (www.goodnet.com/%7Estaheli)\n");
if (argc != 2) /* opps user didn't pass any parameters */
help();
switch (ValidateCDKey(argv[1]))
{
case INVALID_CHAR : puts("This key is either not formatted properly or contains alphanumeric characters.");
break;
case INVALID_LENGTH : puts("This key is neither a valid length for a Microsoft or a OEM CD Key.");
break;
case INVALID_KEY : puts("This is NOT a valid Microsoft CD Key.");
break;
case VALID_KEY : puts("This is a VALID Microsoft CD Key.");
break;
}
}
---- Cut here ---
Email: mindrape@goodnet.com
staheli@goodnet.com
WWW: www.goodnet.com/%7Estaheli