//
//  https://github.com/WelkinXie/AESCipher-Java
//

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;
import java.util.Base64.Decoder;
import java.util.Base64.Encoder;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import java.io.UnsupportedEncodingException;

public class AESCipher {
	
	private static final String IV_STRING = "A-16-Byte-String";
	private static final String charset = "UTF-8";
	 
	public static String aesEncryptString(String content, String key) throws InvalidKeyException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {
		byte[] contentBytes = content.getBytes(charset);
		byte[] keyBytes = key.getBytes(charset);
		byte[] encryptedBytes = aesEncryptBytes(contentBytes, keyBytes);
		Encoder encoder = Base64.getEncoder();
	    return encoder.encodeToString(encryptedBytes);
	}

	public static String aesDecryptString(String content, String key) throws InvalidKeyException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {
		Decoder decoder = Base64.getDecoder();
	    byte[] encryptedBytes = decoder.decode(content);
	    byte[] keyBytes = key.getBytes(charset);
		byte[] decryptedBytes = aesDecryptBytes(encryptedBytes, keyBytes);
	    return new String(decryptedBytes, charset);		
	}
	
	public static byte[] aesEncryptBytes(byte[] contentBytes, byte[] keyBytes) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {
	    return cipherOperation(contentBytes, keyBytes, Cipher.ENCRYPT_MODE);
	}
	
	public static byte[] aesDecryptBytes(byte[] contentBytes, byte[] keyBytes) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {
	    return cipherOperation(contentBytes, keyBytes, Cipher.DECRYPT_MODE);
	}
	
	private static byte[] cipherOperation(byte[] contentBytes, byte[] keyBytes, int mode) throws UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException {
		SecretKeySpec secretKey = new SecretKeySpec(keyBytes, "AES");
		
	    byte[] initParam = IV_STRING.getBytes(charset);
	    IvParameterSpec ivParameterSpec = new IvParameterSpec(initParam);

	    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
	    cipher.init(mode, secretKey, ivParameterSpec);

 	 	return cipher.doFinal(contentBytes);
	}

}