Encrypting and Decrypting String in Java

The Advanced Encryption Standard (AES), also known by its original name Rijndael (Dutch pronunciation: [ˈrɛindaːl]),^[5][6] is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST) in 2001.^[7]

Below is sample java code to encrypt and decrypt a string.

package com.kishore;

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

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Encrypt {

    protected final Logger LOGGER = LoggerFactory.getLogger(this.getClass());
    
    public static void main(String[] args) {
        String encryptString = "45634634";
        final String KEY = "kishore";
        Encrypt obj = new Encrypt();
        String encryptedString = obj.encrypt(encryptString, obj.encryptSecretKey(KEY));
        System.out.println("encryptedString: "+encryptedString);        
        String decyptedString = obj.decrypt(encryptedString, obj.encryptSecretKey(KEY));
        System.out.println("decyptedString: "+decyptedString);
    }
    public SecretKeySpec encryptSecretKey(final String secretKey) {
        MessageDigest sha = null;
        SecretKeySpec encryptApiSecret = null;
        try {
            byte[] key = secretKey.getBytes("UTF-8");
            sha = MessageDigest.getInstance("SHA-1");
            key = sha.digest(key);
            key = Arrays.copyOf(key, 16);
            encryptApiSecret = new SecretKeySpec(key, "AES");
        } catch (final NoSuchAlgorithmException e) {
            LOGGER.error("Exception occurred in encryptApiSecret",e);
        } catch (final UnsupportedEncodingException e) {
            LOGGER.error("Exception occurred in encryptApiSecret",e);
        }
        return encryptApiSecret;
    }
    
    public String decrypt(final String strToDecrypt, final SecretKeySpec secretKey) {
        String decryptedApiKey = "";
        try {
            final Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
            cipher.init(Cipher.DECRYPT_MODE, secretKey);
            byte[] c = Base64.decodeBase64(strToDecrypt.getBytes("UTF-8"));
            decryptedApiKey = new String(cipher.doFinal(c));
        } catch (final Exception e) {
            LOGGER.error("Exception occurred in decrypt",e);
        }
        return decryptedApiKey;
    }

    public String encrypt(final String strToDecrypt, final SecretKeySpec secretKey) {
        String encryptedApiKey = "";
        try {
            final Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
            cipher.init(Cipher.ENCRYPT_MODE, secretKey);
            byte[] c = cipher.doFinal(strToDecrypt.getBytes());
            encryptedApiKey = new String(Base64.encodeBase64(c));
        } catch (final Exception e) {
            LOGGER.error("Exception occurred in encrypt",e);
        }
        return encryptedApiKey;
    }

}