My Java keygen

[chickenbutt]

Was messing around in Java and wrote this up. Improvements?

public final class KeyDecoder
{
  private static int CalculateHash(String licenseName)
  {
	int hash = 0;	for (int i = 0; i < licenseName.length(); i++)
	{
	  int xorValue = licenseName.charAt(i);
	  int rotateSequence = xorValue;	  for (int j = 0; j < 4; j++)
	  {
		int rotateLeft = rotateSequence & 0x3;
		int shiftLeft = rotateLeft;
		int shiftRight = 32 - rotateLeft;
		int rotatedBits = hash >>> shiftRight;		hash = hash << shiftLeft | rotatedBits;
		hash ^= xorValue;		rotateSequence >>= 2;
	  }
	}	return hash + 1 & 0xFFFF;
  }  public static short[] getInfoArray(String registrationName, String registrationCode)
  {
	short[] infoArray = (short[])null;	if ((registrationName != null) && (registrationCode != null))
	{
	  registrationName = registrationName.toUpperCase().trim();
	  registrationCode = registrationCode.toUpperCase().trim();	  StringBuffer sb = new StringBuffer();
	  for (int i = 0; i < registrationCode.length(); i++)
	  {
		char ch = registrationCode.charAt(i);
		if (!Character.isLetter(ch)) {
		  continue;
		}
		sb.append(ch);
	  }	  registrationCode = sb.toString();
	  int registrationCodeLen = registrationCode.length();	  if ((registrationName.length() > 0) && (registrationCodeLen > 0))
	  {
		Vector dataWordList = new Vector();		int checksum = 0;		int offset = 0;
		int chCode = 65;		while (offset < registrationCodeLen)
		{
		  int dataWord = 0;		  for (int i = 0; i < 4; i++)
		  {
			if (offset >= registrationCodeLen)
			  continue;
			int ch = registrationCode.charAt(offset++);			int chDiff = ch >= chCode ? ch - chCode : ch + 26 - chCode;
			dataWord = dataWord << 4 | chDiff - 1;
			chCode = ch;
		  }		  checksum += dataWord;		  dataWordList.add(new Integer(dataWord));
		}		Integer HashCode = (Integer)dataWordList.get(1);
		Integer CheckSum = (Integer)dataWordList.get(dataWordList.size() - 1);		int tCheckSum = CheckSum.intValue();
		if ((checksum - tCheckSum & 0xFFFF) == tCheckSum)
		{
		  int tHashCode = HashCode.intValue();
		  if (tHashCode == CalculateHash(registrationName))
		  {
			int nitems = dataWordList.size() - 3;
			if (nitems > 0)
			{
			  Integer dataWord = (Integer)dataWordList.get(0);
			  int randomNumber = dataWord.intValue() & 0xFFFF;			  infoArray = new short[nitems];
			  for (int i = 0; i < nitems; i++)
			  {
				dataWord = (Integer)dataWordList.get(2 + i);
				infoArray[i] = (short)((dataWord.intValue() ^ randomNumber) & 0xFFFF);
			  }
			}
		  }
		}
	  }
	}	return infoArray;
  }  public static boolean getInfoArray(String registrationName, String registrationCode, short[] infoArray)
  {
	int[] dataWordList = (int[])null;
	int numDataWords = 0;
	int checksum = 0;	boolean validFlag = true;	if ((registrationName != null) && (registrationCode != null))
	{
	  registrationName = registrationName.toUpperCase().trim();
	  registrationCode = registrationCode.toUpperCase().trim();	  StringBuffer sb = new StringBuffer();
	  for (int i = 0; i < registrationCode.length(); i++)
	  {
		char ch = registrationCode.charAt(i);
		if ((ch < 'A') || (ch > 'Z'))
		  continue;
		sb.append(ch);
	  }	  registrationCode = sb.toString();
	} else {
	  validFlag = false;
	}	if (validFlag) {
	  int registrationCodeLen = registrationCode.length();	  if ((registrationName.length() > 0) && (registrationCodeLen > 0))
	  {
		dataWordList = new int[infoArray.length + 3];		int offset = 0;
		int chCode = 65;		while (offset < registrationCodeLen)
		{
		  int dataWord = 0;		  for (int i = 0; i < 4; i++)
		  {
			if (offset >= registrationCodeLen)
			  continue;
			int ch = registrationCode.charAt(offset++);
			int chDiff = ch >= chCode ? ch - chCode : ch + 26 - chCode;
			dataWord = dataWord << 4 | chDiff - 1;
			chCode = ch;
		  }		  checksum += dataWord;		  if (numDataWords < dataWordList.length)
			dataWordList[(numDataWords++)] = dataWord;
		  else
			validFlag = false;
		}
	  }
	  else {
		validFlag = false;
	  }
	}	if (validFlag) {
	  int tCheckSum = dataWordList[(numDataWords - 1)];	  if ((checksum - tCheckSum & 0xFFFF) == tCheckSum) {
		int tHashCode = dataWordList[1];		if (tHashCode == CalculateHash(registrationName)) {
		  int nitems = numDataWords - 3;
		  if (nitems > 0) {
			int randomNumber = dataWordList[0] & 0xFFFF;			for (int i = 0; i < nitems; i++)
			{
			  int dataWord = dataWordList[(2 + i)];
			  infoArray[i] = (short)((dataWord ^ randomNumber) & 0xFFFF);
			}
		  } else {
			validFlag = false;
		  }
		} else {
		  validFlag = false;
		}
	  } else {
		validFlag = false;
	  }
	}	return validFlag;
  }
}public final class KeyDecoder
{
  private static int CalculateHash(String licenseName)
  {
	int hash = 0;	for (int i = 0; i < licenseName.length(); i++)
	{
	  int xorValue = licenseName.charAt(i);
	  int rotateSequence = xorValue;	  for (int j = 0; j < 4; j++)
	  {
		int rotateLeft = rotateSequence & 0x3;
		int shiftLeft = rotateLeft;
		int shiftRight = 32 - rotateLeft;
		int rotatedBits = hash >>> shiftRight;		hash = hash << shiftLeft | rotatedBits;
		hash ^= xorValue;		rotateSequence >>= 2;
	  }
	}	return hash + 1 & 0xFFFF;
  }  public static short[] getInfoArray(String registrationName, String registrationCode)
  {
	short[] infoArray = (short[])null;	if ((registrationName != null) && (registrationCode != null))
	{
	  registrationName = registrationName.toUpperCase().trim();
	  registrationCode = registrationCode.toUpperCase().trim();	  StringBuffer sb = new StringBuffer();
	  for (int i = 0; i < registrationCode.length(); i++)
	  {
		char ch = registrationCode.charAt(i);
		if (!Character.isLetter(ch)) {
		  continue;
		}
		sb.append(ch);
	  }	  registrationCode = sb.toString();
	  int registrationCodeLen = registrationCode.length();	  if ((registrationName.length() > 0) && (registrationCodeLen > 0))
	  {
		Vector dataWordList = new Vector();		int checksum = 0;		int offset = 0;
		int chCode = 65;		while (offset < registrationCodeLen)
		{
		  int dataWord = 0;		  for (int i = 0; i < 4; i++)
		  {
			if (offset >= registrationCodeLen)
			  continue;
			int ch = registrationCode.charAt(offset++);			int chDiff = ch >= chCode ? ch - chCode : ch + 26 - chCode;
			dataWord = dataWord << 4 | chDiff - 1;
			chCode = ch;
		  }		  checksum += dataWord;		  dataWordList.add(new Integer(dataWord));
		}		Integer HashCode = (Integer)dataWordList.get(1);
		Integer CheckSum = (Integer)dataWordList.get(dataWordList.size() - 1);		int tCheckSum = CheckSum.intValue();
		if ((checksum - tCheckSum & 0xFFFF) == tCheckSum)
		{
		  int tHashCode = HashCode.intValue();
		  if (tHashCode == CalculateHash(registrationName))
		  {
			int nitems = dataWordList.size() - 3;
			if (nitems > 0)
			{
			  Integer dataWord = (Integer)dataWordList.get(0);
			  int randomNumber = dataWord.intValue() & 0xFFFF;			  infoArray = new short[nitems];
			  for (int i = 0; i < nitems; i++)
			  {
				dataWord = (Integer)dataWordList.get(2 + i);
				infoArray[i] = (short)((dataWord.intValue() ^ randomNumber) & 0xFFFF);
			  }
			}
		  }
		}
	  }
	}	return infoArray;
  }  public static boolean getInfoArray(String registrationName, String registrationCode, short[] infoArray)
  {
	int[] dataWordList = (int[])null;
	int numDataWords = 0;
	int checksum = 0;	boolean validFlag = true;	if ((registrationName != null) && (registrationCode != null))
	{
	  registrationName = registrationName.toUpperCase().trim();
	  registrationCode = registrationCode.toUpperCase().trim();	  StringBuffer sb = new StringBuffer();
	  for (int i = 0; i < registrationCode.length(); i++)
	  {
		char ch = registrationCode.charAt(i);
		if ((ch < 'A') || (ch > 'Z'))
		  continue;
		sb.append(ch);
	  }	  registrationCode = sb.toString();
	} else {
	  validFlag = false;
	}	if (validFlag) {
	  int registrationCodeLen = registrationCode.length();	  if ((registrationName.length() > 0) && (registrationCodeLen > 0))
	  {
		dataWordList = new int[infoArray.length + 3];		int offset = 0;
		int chCode = 65;		while (offset < registrationCodeLen)
		{
		  int dataWord = 0;		  for (int i = 0; i < 4; i++)
		  {
			if (offset >= registrationCodeLen)
			  continue;
			int ch = registrationCode.charAt(offset++);
			int chDiff = ch >= chCode ? ch - chCode : ch + 26 - chCode;
			dataWord = dataWord << 4 | chDiff - 1;
			chCode = ch;
		  }		  checksum += dataWord;		  if (numDataWords < dataWordList.length)
			dataWordList[(numDataWords++)] = dataWord;
		  else
			validFlag = false;
		}
	  }
	  else {
		validFlag = false;
	  }
	}	if (validFlag) {
	  int tCheckSum = dataWordList[(numDataWords - 1)];	  if ((checksum - tCheckSum & 0xFFFF) == tCheckSum) {
		int tHashCode = dataWordList[1];		if (tHashCode == CalculateHash(registrationName)) {
		  int nitems = numDataWords - 3;
		  if (nitems > 0) {
			int randomNumber = dataWordList[0] & 0xFFFF;			for (int i = 0; i < nitems; i++)
			{
			  int dataWord = dataWordList[(2 + i)];
			  infoArray[i] = (short)((dataWord ^ randomNumber) & 0xFFFF);
			}
		  } else {
			validFlag = false;
		  }
		} else {
		  validFlag = false;
		}
	  } else {
		validFlag = false;
	  }
	}	return validFlag;
  }
}  private void CheckRegistered()
  {
	int todaysDate = (int)(System.currentTimeMillis() / 86400000L);	aboutMessage = null;	if ((username != null) && (username.length() > 0))
	{
	  if ((registrationCode != null) && (registrationCode.length() > 0))
	  {
		short[] infoArray = new short[2];
		if (KeyDecoder.getInfoArray(username, registrationCode, infoArray)) {
		  expiryDate = infoArray[0];
		  iEdition = infoArray[1];		  if ((iEdition >= 0) && (iEdition <= 2)) {
			boolean keyValid = true;
			expiryDate = infoArray[0];			if (expiryDate > 0) {
			  if (expiryDate >= 15286) {
				registeredFlag = true;
			  } else {
				Date date = new Date(expiryDate * 24L * 60L * 60L * 1000L);
				Calendar cal = Calendar.getInstance();
				cal.setTime(date);				int ccyy = cal.get(1);
				int month = cal.get(2);
				int day = cal.get(5);				registerMessage = String.format("Registration code not valid for Product released after %d/%d/%4d", new Object[] { Integer.valueOf(day), Integer.valueOf(month), Integer.valueOf(ccyy) });
				registeredFlag = false;
			  }
			} else if (expiryDate < 0) {
			  if (todaysDate <= -expiryDate) {
				registeredFlag = true;
			  } else {
				Date date = new Date(-expiryDate * 24L * 60L * 60L * 1000L);
				Calendar cal = Calendar.getInstance();
				cal.setTime(date);				int ccyy = cal.get(1);
				int month = cal.get(2);
				int day = cal.get(5);				registerMessage = String.format("Registration code expired on %d/%d/%4d", new Object[] { Integer.valueOf(day), Integer.valueOf(month), Integer.valueOf(ccyy) });
				registeredFlag = false;
			  }
			} else {
			  registerMessage = "Registration code has expired";
			  registeredFlag = false;
			}
		  } else {
			boolean keyValid = false;
			registerMessage = "Registration code is not valid for this product";
			registeredFlag = false;
		  }
		} else {
		  registerMessage = "*** Invalid Key ***";
		  registeredFlag = false;
		}
	  }
	  else
	  {
		registerMessage = "Missing registration code";
		registeredFlag = false;
	  }
	}
	else
	{
	  registerMessage = "Missing username";
	  registeredFlag = false;
	}	if (registeredFlag)
	{
	  switch (iEdition)
	  {
	  case -1:
		setTitle(version + " (Unregistered Edition)");
		break;
	  case 0:
		setTitle(version + " (Personal Edition)");
		break;
	  case 1:
		setTitle(version + " (Business Edition)");
		break;
	  case 2:
		setTitle(version + " (GameCreators Edition)");
		break;
	  default:
		setTitle(version + " (Unknown Edition)");
	  }	  this.registerMenuItem.setVisible(false);
	  this.registerMenuItem.setVisible(true);
	}
	else
	{
	  setTitle(version + " - Trial Version");
	  this.registerMenuItem.setVisible(true);
	}
  }

[Killboy]

Anything not working as expected?

[chickenbutt]

Anything not working as expected?

no. It's actually weak, the hashing function is just a shift+decode function, and the rest just converts underlying segments into date and edition info.

If I was doing a serious one it'd be export friendly RSA off of a HWID that go to a one-time server check which returns a key file that is sent through some RSA+HWID based decryption routines on-load, all under a good control-flow+crypt protector. I think JVM actually has a DRM API, or at least J2ME does I think, that has crypto and some isolation. Isolation is the key though, unfortunatly x86 has none that isn't accessble through debug+trace, except on newer Intel which is only accessible to rich vendors, and I think has been defeated.