package at.gv.egovernment.moa.id.util;

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;

import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;

import at.gv.egovernment.moa.id.BuildException;
import at.gv.egovernment.moa.id.config.auth.AuthConfigurationProvider;
import at.gv.egovernment.moa.logging.Logger;

public class SessionEncrytionUtil {

	static SecretKey secret = null;

	static {
		try {
			String key = AuthConfigurationProvider.getInstance().getMOASessionEncryptionKey();
			
			if (key != null) {
				SecretKeyFactory factory;

					factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
					KeySpec spec = new PBEKeySpec(key.toCharArray(), "TestSALT".getBytes(), 1024, 128);
					SecretKey tmp = factory.generateSecret(spec);
					secret = new SecretKeySpec(tmp.getEncoded(), "AES");
					
					
			} else {
				Logger.warn("MOASession encryption is deaktivated.");
			}
			
		} catch (Exception e) {
			Logger.warn("MOASession encryption can not be inizialized.", e);
		}
		
	}
	
	public static byte[] encrypt(byte[] data) throws BuildException {
		Cipher cipher;
		
		if (secret != null) {
			try {
				cipher = Cipher.getInstance("AES/ECB/"+"ISO10126Padding");
			    cipher.init(Cipher.ENCRYPT_MODE, secret);
				
			    Logger.debug("Encrypt MOASession");
			    return cipher.doFinal(data);
			    
			} catch (Exception e) {
				Logger.warn("MOASession is not encrypted",e);
				throw new BuildException("MOASession is not encrypted", new Object[]{}, e);
			}
		} else
			return data;
	}
	
	public static byte[] decrypt(byte[] data) throws BuildException {
		Cipher cipher;
		
		if (secret != null) {
			try {
				cipher = Cipher.getInstance("AES/ECB/"+"ISO10126Padding");
			    cipher.init(Cipher.DECRYPT_MODE, secret);
				
			    Logger.debug("Decrypt MOASession");
			    return cipher.doFinal(data);
			    
			} catch (Exception e) {
				Logger.warn("MOASession is not decrypted",e);
				throw new BuildException("MOASession is not decrypted", new Object[]{}, e);
			}
		} else
		return data;
	}
}