Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
//License from project: Apache License 

import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class Main {
    public static byte[] decipherAes256(byte[] encrypedPwdBytes, String password) throws NullPointerException {

        if (password == null || password.length() == 0) {
            throw new NullPointerException("Please give Password");
        }

        if (encrypedPwdBytes == null || encrypedPwdBytes.length <= 0) {
            throw new NullPointerException("Please give encrypedPwdBytes");
        }

        try {
            SecretKey key = getKey(password);

            // IMPORTANT TO GET SAME RESULTS ON iOS and ANDROID
            final byte[] iv = new byte[16];
            Arrays.fill(iv, (byte) 0x00);
            IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);

            // cipher is not thread safe
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
            cipher.init(Cipher.DECRYPT_MODE, key, ivParameterSpec);
            byte[] decryptedValueBytes = (cipher.doFinal(encrypedPwdBytes));

            return decryptedValueBytes;

        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (InvalidAlgorithmParameterException e) {
            e.printStackTrace();
        }
        return null;
    }

    private static SecretKeySpec getKey(String password) throws UnsupportedEncodingException {

        // You can change it to 128 if you wish
        int keyLength = 256;
        byte[] keyBytes = new byte[keyLength / 8];
        // explicitly fill with zeros
        Arrays.fill(keyBytes, (byte) 0x0);

        // if password is shorter then key length, it will be zero-padded
        // to key length
        byte[] passwordBytes = password.getBytes("UTF-8");
        int length = passwordBytes.length < keyBytes.length ? passwordBytes.length : keyBytes.length;
        System.arraycopy(passwordBytes, 0, keyBytes, 0, length);
        SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
        return key;
    }
}