CipherManager.java

package net.rehacktive.waspdb.internals.collision;

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
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.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;


/**
 * Created by stefano on 06/08/2014.
 */
public class CipherManager {

    private int ITERATIONS = 10000;
    private int KEYSIZE = 256;

    public static String cipher_algorithm = "AES/CBC/PKCS7PADDING";
    public static String key_algorithm = "PBKDF2WithHmacSHA1";
    public static String secretKeyAlgorithm = "AES";

    protected Key key;

    protected static CipherManager instance = null;

    private CipherManager() {
//        Security.insertProviderAt(new org.spongycastle.jce.provider.BouncyCastleProvider(), 1);
//        Provider[] providers = Security.getProviders();
//        for (Provider provider : providers) {
//            Log.i("CRYPTO","provider: "+provider.getName());
//            Set<Provider.Service> services = provider.getServices();
//            for (Provider.Service service : services) {
//                Log.i("CRYPTO","  key_algorithm: "+service.getAlgorithm());
//            }
//        }
    }

    public static CipherManager getInstance(char[] p, byte[] s)  {
        if (instance == null) {
            instance = new CipherManager();
            try {
                instance.generateSK(p, s);
            }
            catch(Exception e) {
                e.printStackTrace();
                return null;
            }
        }
        return instance;
    }

    private void generateSK(char[] passPhrase, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, InvalidAlgorithmParameterException, InvalidKeyException {
        SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance(key_algorithm);

        KeySpec spec = new PBEKeySpec(passPhrase,salt,ITERATIONS, KEYSIZE);
        SecretKey secretKey = secretKeyFactory.generateSecret(spec);

        key = new SecretKeySpec(secretKey.getEncoded(), secretKeyAlgorithm);
    }

    protected Cipher getEncCipher() {
        try {
            Cipher cipher = Cipher.getInstance(cipher_algorithm);
            cipher.init(Cipher.ENCRYPT_MODE, key);

            return cipher;
        }catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    protected Cipher getDecCipher(byte[] iv) {
        try {
            Cipher cipher = Cipher.getInstance(cipher_algorithm);
            IvParameterSpec ivParams = new IvParameterSpec(iv);
            cipher.init(Cipher.DECRYPT_MODE, key, ivParams);

            return cipher;
        }catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

}