JoaoSerra

/*
 *
 * Copyright (c) 2009, Mulder3
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Mulder3 <mulder3@mulder3.net>
 *
 */

import java.io.*;
import java.security.spec.AlgorithmParameterSpec;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.Cipher;


public class TV2xmlDecrypt {

    public static void main(String[] args) {

           System.out.println("Microsoft Mediaroom XML decrypt by Mulder3 <mulder3@mulder3.net>");
           if (args.length!=3 || args[2].length()!=32){
               System.out.println("Usage: TV2xmlDecrypt inFile outFile AESkey(16bytes hex string without spaces or colons)");
               System.out.println("Example: TV2xmlDecrypt LoginEx_encrypted.bin LoginEx.xml 0123456789ABCDEF0123456789ABCDEF");
               System.exit(0);
           }
           System.out.println("Trying to decrypt "+args[0]+"...");
           try{
                FileInputStream inFile = new FileInputStream(new File(args[0]));
                FileOutputStream outFile = new FileOutputStream(new File(args[1]));
                decryptTV2xml(inFile, outFile, args[3]);
                inFile.close();
                outFile.close();
           } catch(Exception e){
                e.printStackTrace();
           }
           System.out.println("File successfully decrypted... saved to "+args[1]+"...");
    }

    public static void decryptTV2xml(FileInputStream in, FileOutputStream out, String aeskey) throws Exception {

        boolean isFirstBock = true;
        int offset = 0;
        int padding = 0;
        byte[] buffer;
        byte[] buffer2;
        byte[] decryptedXML = null;
        byte[] iv = new byte[16];
        byte[] OMAC1signature = new byte[16];
        SecretKeySpec key = new SecretKeySpec(hexToByteArray(aeskey), "AES");

        while(true){
            if (isFirstBock){
              buffer = new byte[1+16+8+4096+16]; //padding/version byte + 16bytes iv + 8bytes ramdom data + 4096 bytes encrypted block + 16bytes OMAC1 signature
              offset = in.read(buffer, 0, (1+16+8+4096+16));
              if (offset==-1) break;
              if (((buffer[0] >> 4) & 15) != 1){ System.out.println("ERROR: Stream version unknown"); System.exit(0);}
              padding = buffer[0] & 15;
              if (padding > 15){ System.out.println("ERROR: Invalid padding specified"); System.exit(0);}
              System.arraycopy(buffer, 1, iv, 0, 16);
              System.arraycopy(buffer, offset-16, OMAC1signature, 0, 16);
              buffer2 = new byte[offset-(1+16+8+16)]; //padding/version byte + 16bytes iv + 8bytes ramdom data + 16bytes OMAC1 signature
              System.arraycopy(buffer, (1+16+8), buffer2, 0, offset-(1+16+8+16));
              //VerifyOMAC1signature(OMAC1signature,buffer2); //NOT IMPLEMENTED!!
              decryptedXML=decryptAesBlock(buffer2,iv, key, padding);
              out.write(decryptedXML, 0, decryptedXML.length);
              isFirstBock=false;

            } else {

              buffer = new byte[1+4096+16]; //padding/version byte + 4096 bytes encrypted block + 16bytes OMAC1 signature
              offset = in.read(buffer, 0, (1+4096+16));
              if (offset==-1) break;
              if (((buffer[0] >> 4) & 15) != 1){ System.out.println("ERROR: Stream version unknown"); System.exit(0);}
              padding = buffer[0] & 15;
              if (padding > 15){ System.out.println("ERROR: Invalid padding specified"); System.exit(0);}
              System.arraycopy(buffer, offset-16, OMAC1signature, 0, 16);
              buffer2 = new byte[offset-(1+16)]; //padding/version byte + 16bytes OMAC1 signature
              System.arraycopy(buffer, 1, buffer2, 0, offset-(1+16));
              //VerifyOMAC1signature(OMAC1signature,buffer2); //NOT IMPLEMENTED!!!
              decryptedXML=decryptAesBlock(buffer2,iv, key,padding);
              out.write(decryptedXML, 0, decryptedXML.length);

            }
        }
    }

    private static byte[] decryptAesBlock(byte[] block, byte[] iv, SecretKeySpec key, int padding) throws Exception { // Java crypto subsystem throws a bunch of checked exceptions, so, i didn't bother to declare them all... it's a bad practice, i know...

        Cipher decipher;
        AlgorithmParameterSpec ivSpec = new IvParameterSpec(iv);
        byte[] decryptedData = new byte[block.length];
        byte[] result = new byte[block.length-padding];
        decipher = Cipher.getInstance("AES/CBC/NoPadding");
        decipher.init(Cipher.DECRYPT_MODE, key, ivSpec);
        decryptedData=decipher.doFinal(block, 0, block.length);
        System.arraycopy(decryptedData, 0, result, 0, decryptedData.length-padding);

        return result;
    }

    private static byte[] hexToByteArray(String hexString) {
        String s = hexString.toLowerCase();
        byte[] data = new byte[s.length() / 2];
        for (int i = 0; i < s.length(); i += 2) {
          data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i+1), 16));
        }
        return data;
    }

}