AESDemo

/*
Taken from: http://stackoverflow.com/questions/8731671/aesdecryption-in-blackberry
*/

import javax.crypto.*;
import javax.crypto.spec.SecretKeySpec;
import java.io.*;
import java.security.NoSuchAlgorithmException;
import java.security.MessageDigest;
import java.security.*;

class AESDemo {
    private static Cipher eCipher, dCipher;
    private static byte[] buf = new byte[1024];

    private static byte[] getMD5(String input){
        try {
            byte[] bytesOfMessage = input.getBytes("UTF-8");
            MessageDigest md = MessageDigest.getInstance("MD5");
            return md.digest(bytesOfMessage);
        }
        catch (Exception e){
            return null;
        }
    }

    private static void init_crypto(String key){
        SecretKeySpec skey = new SecretKeySpec(getMD5(key), "AES");

        try {
            Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
            eCipher = Cipher.getInstance("AES/ECB/PKCS7Padding", "BC");
            dCipher = Cipher.getInstance("AES/ECB/PKCS7Padding", "BC");

            eCipher.init(Cipher.ENCRYPT_MODE, skey);
            dCipher.init(Cipher.DECRYPT_MODE, skey);
        }
        catch (Exception e){
            e.printStackTrace();
        }
    }



    public static void encrypt(File fin, File fout){

        try {
                    InputStream in = new FileInputStream(fin);
            OutputStream out = new FileOutputStream(fout);
            out = new CipherOutputStream(out, eCipher);

            int numRead = 0;
            while ((numRead = in.read(buf)) >= 0){
                out.write(buf, 0, numRead);
            }
            out.close();
        }
        catch (IOException e){
            e.printStackTrace();
        }
    }


    public static void decrypt(File fin, File fout){

        try {
            InputStream in = new FileInputStream(fin);
            OutputStream out = new FileOutputStream(fout);
            in = new CipherInputStream(in, dCipher);

            int numRead = 0;
            while ((numRead = in.read(buf)) >= 0) {
                out.write(buf, 0, numRead);
            }
            out.close();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static byte[] readFile(File file) throws IOException {

        byte []buffer = new byte[(int) file.length()];
        InputStream ios = null;
        try {
            ios = new FileInputStream(file);
            if ( ios.read(buffer) == -1 ) {
                throw new IOException("EOF reached while trying to read the whole file");
            }
        }
        finally {
            try {
                if ( ios != null ) ios.close();
            }
            catch ( IOException e) {
            }
        }

        return buffer;
    }

    public static void main(String args[]) throws IOException, Exception{
        String mode = args[0];
        init_crypto("Hello world");

        if (mode.equals("-e")) encrypt(new File(args[1]), new File(args[2]));
        else if (mode.equals("-d")) decrypt(new File(args[1]), new File(args[2]));
    }
}