<?php
/**
 * Created by PhpStorm.
 * User: sunil
 * Date: 28/11/18
 * Time: 12:39 PM
 */

namespace App;


use Illuminate\Http\Request;
use Illuminate\Support\Facades\Storage;

class AesCipher {

    private const OPENSSL_CIPHER_NAME = "aes-128-cbc";
    private const CIPHER_KEY_LEN = 16; //128 bits
    private static function fixKey($key) {

        if (strlen($key) < AesCipher::CIPHER_KEY_LEN) {
            //0 pad to len 16
            return str_pad("$key", AesCipher::CIPHER_KEY_LEN, "0");
        }

        if (strlen($key) > AesCipher::CIPHER_KEY_LEN) {
            //truncate to 16 bytes
            return substr($str, 0, AesCipher::CIPHER_KEY_LEN);
        }
        return $key;
    }
    /**
     * Encrypt data using AES Cipher (CBC) with 128 bit key
     *
     * @param type $key - key to use should be 16 bytes long (128 bits)
     * @param type $iv - initialization vector
     * @param type $data - data to encrypt
     * @return encrypted data in base64 encoding with iv attached at end after a :
     */
    static function encrypt($key, $iv, $data) {
        $encodedEncryptedData = base64_encode(openssl_encrypt($data, AesCipher::OPENSSL_CIPHER_NAME, AesCipher::fixKey($key), OPENSSL_RAW_DATA, $iv));
        $encodedIV = base64_encode($iv);
        $encryptedPayload = $encodedEncryptedData.":".$encodedIV;
        return $encryptedPayload;
    }
    /**
     * Decrypt data using AES Cipher (CBC) with 128 bit key
     *
     * @param type $key - key to use should be 16 bytes long (128 bits)
     * @param type $data - data to be decrypted in base64 encoding with iv attached at the end after a :
     * @return decrypted data
     */
    static function decrypt($key, $data) {
        $data = base64_decode($data);
        //$parts = explode(':', $data); //Separate Encrypted data from iv.
        $encrypted = array_slice($data,16);
        $iv = array_slice($data,-16);
        $decryptedData = openssl_decrypt(base64_decode($encrypted), AesCipher::OPENSSL_CIPHER_NAME, AesCipher::fixKey($key), OPENSSL_RAW_DATA, base64_decode($iv));
        return $decryptedData;
    }
};
$decrypted = AesCipher::decrypt('0123456789abcdef', 'G0a6cK+sxBkSwyCjcG4efA==:YWJjZGVmOTg3NjU0MzIxMA==');