Implement AES Encryption in Android

Question

I found this java AES encryption on the internet. Can I modify and use this java code in my android application? Actually I don't know whether it's suitable for my android device. If I can use it, does that mean that I can modify this java code?

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;
/**
Aes encryption
*/
public class AES
{

    private static SecretKeySpec secretKey ;
    private static byte[] key ;

    private static String decryptedString;
    private static String encryptedString;

    public static void setKey(String myKey){


        MessageDigest sha = null;
        try {
            key = myKey.getBytes("UTF-8");
            System.out.println(key.length);
            sha = MessageDigest.getInstance("SHA-1");
            key = sha.digest(key);
            key = Arrays.copyOf(key, 16); // use only first 128 bit
            System.out.println(key.length);
            System.out.println(new String(key,"UTF-8"));
            secretKey = new SecretKeySpec(key, "AES");


        } catch (NoSuchAlgorithmException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }



    }

    public static String getDecryptedString() {
        return decryptedString;
    }
    public static void setDecryptedString(String decryptedString) {
        AES.decryptedString = decryptedString;
    }
    public static String getEncryptedString() {
        return encryptedString;
    }
    public static void setEncryptedString(String encryptedString) {
        AES.encryptedString = encryptedString;
    }
    public static String encrypt(String strToEncrypt)
    {
        try
        {
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");

            cipher.init(Cipher.ENCRYPT_MODE, secretKey);


            setEncryptedString(Base64.encodeBase64String(cipher.doFinal(strToEncrypt.getBytes("UTF-8"))));

        }
        catch (Exception e)
        {

            System.out.println("Error while encrypting: "+e.toString());
        }
        return null;
    }
    public static String decrypt(String strToDecrypt)
    {
        try
        {
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");

            cipher.init(Cipher.DECRYPT_MODE, secretKey);
            setDecryptedString(new String(cipher.doFinal(Base64.decodeBase64(strToDecrypt))));

        }
        catch (Exception e)
        {

            System.out.println("Error while decrypting: "+e.toString());
        }
        return null;
    }
    public static void main(String args[])
    {
                final String strToEncrypt = "My text to encrypt";
                final String strPssword = "encryptor key";
                AES.setKey(strPssword);

                AES.encrypt(strToEncrypt.trim());

                System.out.println("String to Encrypt: " + strToEncrypt); 
                System.out.println("Encrypted: " + AES.getEncryptedString());

                final String strToDecrypt =  AES.getEncryptedString();
                AES.decrypt(strToDecrypt.trim());

                System.out.println("String To Decrypt : " + strToDecrypt);
                System.out.println("Decrypted : " + AES.getDecryptedString());

    }

}

source: http://aesencryption.net/

Could you please describe what you want to do? You can use any code anywhere. But will it do what you want? So what do you want to do? — qwerty_so
– qwerty_so, Commented Jan 5, 2015 at 18:17
i want to encrypt data from Android application into MySQL database using AES Encryption — MSR
– MSR, Commented Jan 5, 2015 at 18:26

aschattney · Accepted Answer · 2015-01-05 19:49:39Z

When i implemented AES encryption in an android application, i had to specify the provider BouncyCastle when instantiating the cipher.

Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding","BC");

you should consider using cbc mode since ecb mode is not really secure.

Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding","BC");

After little modification of your code, this should work:

import android.util.Base64;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Random;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
/**
Aes encryption
*/
public class AES
{

    private static SecretKeySpec secretKey ;
    private static byte[] key ;
    private static byte[] iv;
    private static String decryptedString;
    private static String encryptedString;

    public static void setKey(String myKey){


        MessageDigest sha = null;
        try {
            key = myKey.getBytes("UTF-8");
            System.out.println(key.length);
            sha = MessageDigest.getInstance("SHA-1");
            key = sha.digest(key);
            key = Arrays.copyOf(key, 16); // use only first 128 bit
            secretKey = new SecretKeySpec(key, "AES");
            iv = new byte[]{11,53,63,87,11,69,63,28,0,9,18,99,95,23,45,8};

        } catch (NoSuchAlgorithmException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }



    }

    public static String getDecryptedString() {
        return decryptedString;
    }
    public static void setDecryptedString(String decryptedString) {
        AES.decryptedString = decryptedString;
    }
    public static String getEncryptedString() {
        return encryptedString;
    }
    public static void setEncryptedString(String encryptedString) {
        AES.encryptedString = encryptedString;
    }
    public static String encrypt(String strToEncrypt)
    {
        try
        {
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding","BC");
            cipher.init(Cipher.ENCRYPT_MODE, secretKey,new IvParameterSpec(iv));
            setEncryptedString(Base64.encodeToString(cipher.doFinal(strToEncrypt.getBytes("UTF-8")),Base64.DEFAULT));

        }
        catch (Exception e)
        {

            System.out.println("Error while encrypting: "+e.toString());
        }
        return null;
    }
    public static String decrypt(String strToDecrypt)
    {
        try
        {
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7PADDING","BC");
            cipher.init(Cipher.DECRYPT_MODE, secretKey,new IvParameterSpec(iv));
            String decoded = new String(cipher.doFinal(Base64.decode(strToDecrypt,Base64.DEFAULT)), Charset.forName("UTF-8"));
            setDecryptedString(decoded);

        }
        catch (Exception e)
        {

            System.out.println("Error while decrypting: "+e.toString());
        }
        return null;
    }

}

at com.android.org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineInit(BaseBlockCipher.java:410)

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