EncDecJDBCPass.java

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import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;
/**
 *
 * @author aksarav
 */
public class EncDecJDBCPass {
    
    private static final String ALGORITHM = "AES";

    private static final String defaultSecretKey = "PHRASETOREPLACE";

    private Key secretKeySpec;

    public EncDecJDBCPass() throws InvalidKeyException, NoSuchAlgorithmException, NoSuchPaddingException,
            UnsupportedEncodingException {
        this(null);
    }

    public EncDecJDBCPass(String secretKey) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
            UnsupportedEncodingException {
        this.secretKeySpec = generateKey(secretKey);
    }

    public String encrypt(String plainText) throws InvalidKeyException, NoSuchAlgorithmException,
            NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
        byte[] encrypted = cipher.doFinal(plainText.getBytes("UTF-8"));
        return asHexString(encrypted);
    }

    public String decrypt(String encryptedString) throws InvalidKeyException, IllegalBlockSizeException,
            BadPaddingException, NoSuchAlgorithmException, NoSuchPaddingException {
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
        byte[] original = cipher.doFinal(toByteArray(encryptedString));
        return new String(original);
    }

    private Key generateKey(String secretKey) throws UnsupportedEncodingException, NoSuchAlgorithmException {
        if (secretKey == null) {
            secretKey = defaultSecretKey;
        }
        byte[] key = (secretKey).getBytes("UTF-8");
        MessageDigest sha = MessageDigest.getInstance("SHA-1");
        key = sha.digest(key);
        key = Arrays.copyOf(key, 16); // use only the first 128 bit
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        kgen.init(128); // 192 and 256 bits may not be available

        return new SecretKeySpec(key, ALGORITHM);
    }

    private final String asHexString(byte buf[]) {
        StringBuffer strbuf = new StringBuffer(buf.length * 2);
        int i;
        for (i = 0; i < buf.length; i++) {
            if (((int) buf[i] & 0xff) < 0x10) {
                strbuf.append("0");
            }
            strbuf.append(Long.toString((int) buf[i] & 0xff, 16));
        }
        return strbuf.toString();
    }

    private final byte[] toByteArray(String hexString) {
        int arrLength = hexString.length() >> 1;
        byte buf[] = new byte[arrLength];
        for (int ii = 0; ii < arrLength; ii++) {
            int index = ii << 1;
            String l_digit = hexString.substring(index, index + 2);
            buf[ii] = (byte) Integer.parseInt(l_digit, 16);
        }
        return buf;
    }

    public static void main(String[] args) throws Exception {
        if (args.length == 1 || args.length == 2) {
            String plainText = args[0];
            String secretKey = args.length == 2 ? args[1] : null;
            EncDecJDBCPass aes = null;
            if (secretKey == null) {
                aes = new EncDecJDBCPass();
            } else {
                aes = new EncDecJDBCPass(secretKey);
            }
            String encryptedString = aes.encrypt(plainText);
            System.out.println("=> ENCRYPTED PASSWORD : " + encryptedString);
        } else {
            System.out.println("USAGE: java -jar SecureTomcatJDBC.jar StringToEncrypt");
        }
    }

    
}