CryptoUtils.java

/*
 * This file is part of FTB Launcher.
 *
 * Copyright © 2012-2016, FTB Launcher Contributors <https://github.com/Slowpoke101/FTBLaunch/>
 * FTB Launcher is licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.ftb.util;

import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.util.Arrays;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.digest.DigestUtils;

import net.ftb.log.Logger;

public class CryptoUtils
{

	/**
	 * Newer implementation available if possible use {@link #decrypt(String str)}
	 * @param str string to decrypt
	 * @param key decryption key
	 * @return decrypted string or "" if fails
	 */
	@Deprecated
	public static String decryptLegacy (String str, byte[] key)
	{
		BigInteger in = new BigInteger(str, 16).xor(new BigInteger(1, key));
		try
		{
			return new String(in.toByteArray(), "utf8");
		}
		catch (UnsupportedEncodingException e)
		{
			return "";
		}
		catch (NumberFormatException e)
		{
			Logger.logError("Error occurred during legacy decryption");
			return "";
		}
	}

	/**
	 * Newer implementation available if possible use {@link #encrypt(String str)}
	 * @param str string to decrypt
	 * @param key decryption key
	 * @return decrypted string or "" if fails
	 */
	@Deprecated
	public static String encryptLegacy (String str, byte[] key)
	{
		BigInteger str2;
		try
		{
			str2 = new BigInteger(str.getBytes("utf8")).xor(new BigInteger(1, key));
		}
		catch (UnsupportedEncodingException e)
		{
			return "";
		}
		return String.format("%040x", str2);
	}

	/**
	 * Method to AES decrypt string if fails, will attempt to use {@link #decryptLegacy(String str, byte[] key)}
	 * @param str string to decrypt
	 * @return decrypted string or "" if legacy fails
	 */
	public static String decrypt (String str)
	{
		byte[] keyMac = OSUtils.getMacAddress();
		byte[] keyHardware = OSUtils.getHardwareID();
		String s;
		try
		{
			Cipher aes = Cipher.getInstance("AES");
			if (keyHardware != null && keyHardware.length > 0)
			{
				Logger.logDebug("trying with hardware id");
				try
				{
					aes.init(Cipher.DECRYPT_MODE, new SecretKeySpec(pad(keyHardware), "AES"));
					s = new String(aes.doFinal(Base64.decodeBase64(str)), "utf8");
					if (s.startsWith("FDT:") && s.length() > 4)
					{
						Logger.logDebug("hardware id ok");
						return s.split(":", 2)[1];// it was decrypted with HW UUID
					}
				}
				catch (Exception e)
				{
					Logger.logDebug("foo", e);
				}
			}

			// did not open, try again with old mac based key
			Logger.logDebug("Tryinng with mac address");
			aes.init(Cipher.DECRYPT_MODE, new SecretKeySpec(pad(keyMac), "AES"));
			s = new String(aes.doFinal(Base64.decodeBase64(str)), "utf8");
			if (s.startsWith("FDT:") && s.length() > 4)
			{
				Logger.logDebug("mac address ok");
				return s.split(":", 2)[1];// we don't want the decryption test
			}
			else
			{
				Logger.logDebug("Trying some legacy");
				return decryptLegacy(str, keyMac);
			}
		}
		catch (Exception e)
		{
			Logger.logError("Error Decrypting information, attempting legacy decryption", e);
			return decryptLegacy(str, keyMac);
		}
	}

	/**
	 * Method to AES encrypt string if fails, will attempt to use {@link #encryptLegacy(String str, byte[] key)}
	 * @param str string to encrypt
	 * @return encrypted string or "" if legacy fails
	 */
	public static String encrypt (String str)
	{
		byte[] keyMac = OSUtils.getMacAddress();
		byte[] keyHardware = OSUtils.getHardwareID();
		try
		{
			Cipher aes = Cipher.getInstance("AES");
			if (keyHardware != null && keyHardware.length > 0)
			{
				Logger.logDebug("trying hardware id");
				aes.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(pad(keyHardware), "AES"));
				Logger.logDebug("hardware id ok");
				return Base64.encodeBase64String(aes.doFinal(("FDT:" + str).getBytes("utf8")));
			}
			Logger.logDebug("trying mac address");
			aes.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(pad(keyMac), "AES"));
			Logger.logDebug("mac address ok");
			return Base64.encodeBase64String(aes.doFinal(("FDT:" + str).getBytes("utf8")));
		}
		catch (Exception e)
		{
			Logger.logError("Error Encrypting information, reverting to legacy format", e);
			return encryptLegacy(str, keyMac);
		}
	}

	/**
	 * method to pad AES keys by using the sha1Hex hash on them
	 * @param key key to pad
	 * @return padded key
	 */
	public static byte[] pad (byte[] key)
	{
		try
		{
			return Arrays.copyOf(DigestUtils.sha1Hex(key).getBytes("utf8"), 16);
		}
		catch (UnsupportedEncodingException e)
		{
			Logger.logError("error encoding padded key!", e);
			return Arrays.copyOf(DigestUtils.sha1Hex(key).getBytes(), 16);
		}
	}
}