116 lines
2.6 KiB
C
116 lines
2.6 KiB
C
#include "stdafx.h"
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#include "Random.h"
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#include "Generator.h"
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#include <Time.h>
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static const TCHAR szBaseChars[] = _T("BCDFGHJKMPQRTVWXY346789");
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static const BYTE base = (sizeof(szBaseChars) / sizeof(TCHAR)) - 1;
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static const UINT64 uPrivKey[] = { 0x0a0d212073, 0x7468676972, 0x20736e617274 };
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// Create an Adler32 checksum according to the provided szInput.
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static DWORD
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ck_adler32(LPCTSTR szInput,
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DWORD dwLen)
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{
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DWORD a = 1,
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b = 0,
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i;
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for (i = 0; i < dwLen; i++) {
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// XXX: This is a really naive way to "convert" to ANSI
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a += szInput[i] & 0xff;
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b += a;
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}
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a %= 65521;
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b %= 65521;
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return ((b << 16) | a);
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}
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// Encode a number as a "sanitized Microsoft" base-23 string
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static BOOL
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EncodeNumber(LPVOID lpIn,
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DWORD dwSize,
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LPTSTR szOut)
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{
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UINT64 uNum = 0;
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TCHAR *ptr = szOut + 5;
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if (!lpIn || !szOut) return FALSE;
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if (dwSize > 8) return FALSE;
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// XXX: Win32 is always little endian, so should be fine?
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CopyMemory(&uNum, lpIn, dwSize);
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*(ptr + 1) = 0;
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do {
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*ptr-- = szBaseChars[uNum % base];
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uNum /= base;
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} while (ptr >= szOut);
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return TRUE;
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}
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BOOL
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GenerateKey(LPCTSTR szInput,
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LPTSTR szOut)
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{
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/* In the original implementation, this just generated random
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* "digits." I went too far with the bit, so now the "keys" have
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* some procedural generation! They're still structured similarly:
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*
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* XXXXX-YYYYY-ZZZZZ
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*
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* XXXXX is a random DWORD (shifted right 2 bytes to look more
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* random) and XORed by the first private key QWORD.
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* YYYYY is an Adler32 checksum of the user input, XORed by the
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* second private key QWORD.
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* Finally, ZZZZZ is the Adler32 checksum of "XXXXX-YYYYY", XORed
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* by the third private key QWORD.
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*/
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static BOOL bSeeded = FALSE;
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UINT64 uRandom;
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UINT64 dwChecksum, dwFinalSum;
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LPTSTR szPtr = szOut;
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if (!szInput || !szOut) return FALSE;
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if (!bSeeded) {
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xorsrand((unsigned)time(NULL));
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bSeeded = TRUE;
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}
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// generate segment one
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uRandom = ((xorrand() & 0xffff) << 16) ^ uPrivKey[0];
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if (!EncodeNumber(&uRandom, sizeof(UINT64), szPtr)) {
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return FALSE;
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}
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szPtr += 5;
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*szPtr++ = _T('-');
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// ... and segment 2
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dwChecksum = ck_adler32(szInput, (DWORD)_tcslen(szInput)) ^
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uPrivKey[1];
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if (!EncodeNumber(&dwChecksum, sizeof(DWORD), szPtr)) {
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return FALSE;
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}
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szPtr += 5;
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*szPtr++ = _T('-');
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// ... finally, segment 3
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dwFinalSum = ck_adler32(szOut, 11) ^ uPrivKey[2];
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if (!EncodeNumber(&dwFinalSum, sizeof(DWORD), szPtr)) {
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return FALSE;
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}
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szPtr += 5;
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*szPtr = 0;
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return TRUE;
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} |