cl.niclabs.tscrypto.common.messages.EncryptedData.java Source code

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Here is the source code for cl.niclabs.tscrypto.common.messages.EncryptedData.java

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/*
Copyright 2013 NIC Chile Research Labs
This file is part of TsCrypto.
    
TsCrypto is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
    
TsCrypto is distributed in the hope that 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 TsCrypto.  If not, see <http://www.gnu.org/licenses/>.
 */

package cl.niclabs.tscrypto.common.messages;

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

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import cl.niclabs.tscrypto.common.messages.TSMessage;
import org.apache.commons.codec.binary.Base64;

import com.google.gson.Gson;
import com.google.gson.JsonSyntaxException;

import cl.niclabs.tscrypto.common.encryption.KeyChain;
import cl.niclabs.tscrypto.common.encryption.KeyTool;
import cl.niclabs.tscrypto.common.utils.Util;

public class EncryptedData extends TSMessage {
    private static final int KEYSIZE_AES = 128;

    /** data encrypted using AES */
    public String encryptedData;
    /** AES key encrypted with RSA's public key specified by the alias */
    public String encryptedKey;
    /** alias of the RSA's public key used to encrypt/decrypt the AES key */
    public String rsaKeyAlias;

    /**
     * Constructor for encrypted data
     * @param rsaKeyAlias alias of the RSA's public key of the receiver
     * @param blob data to be encrypted
     */
    public EncryptedData(String rsaKeyAlias, byte[] blob) {
        super("encrypted-data", "1.0");
        this.rsaKeyAlias = rsaKeyAlias;
        addData(blob);
    }

    /**
     * Returns a decrypted version of the included data
     * @return
     * @throws NoSuchAlgorithmException
     * @throws NoSuchPaddingException
     * @throws InvalidKeyException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     */
    public byte[] decrypt() throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
            IllegalBlockSizeException, BadPaddingException {

        byte[] plainAESKey = KeyChain.getInstance().decrypt(rsaKeyAlias, encryptedKey);
        SecretKeySpec skeySpec = new SecretKeySpec(plainAESKey, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        return cipher.doFinal(Base64.decodeBase64(encryptedData));
    }

    private byte[] encryptAES(SecretKeySpec skeySpec, byte[] data) {

        byte[] encrypted = null;

        try {
            // Instantiate the cipher
            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec);

            encrypted = cipher.doFinal(data);
        } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException
                | BadPaddingException e) {
            e.printStackTrace();
        }

        return encrypted;
    }

    private static SecretKeySpec generateAESKey() {
        SecretKeySpec skeySpec = null;
        try {
            KeyGenerator keyGen = KeyGenerator.getInstance("AES");
            keyGen.init(KEYSIZE_AES);

            // Generate the secret key specs.
            SecretKey secretKey = keyGen.generateKey();

            skeySpec = new SecretKeySpec(secretKey.getEncoded(), "AES");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }

        return skeySpec;
    }

    private byte[] encrypt(byte[] data) {
        return KeyTool.getInstance().encrypt(this.rsaKeyAlias, data);
    }

    private void addData(byte[] blob) {
        SecretKeySpec skeySpec = generateAESKey();
        encryptedData = new String(Base64.encodeBase64(encryptAES(skeySpec, blob)));
        encryptedKey = new String(Base64.encodeBase64(encrypt(skeySpec.getEncoded())));
    }

}