<?php
namespace ACES\Common;

use ACES\Common\Exception\EncryptExceptoin;
use ACES\Common\Exception\DecryptException;

/**
 * Key Encryption Class
 *
 * <P>
 *
 * @version 1.0
 */

class KeyEncryption {
    const RANDOM_SIZE = 16;
    const ZERO_IV = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
    
    public static function encrypt($mkey, $pt) 
    {
        $rsec = Crypto::secureRandom(self::RANDOM_SIZE);
        $iv = str_pad($rsec, Crypto::CIPHER_IV_SIZE, "\x00");
        
        $ct_data = openssl_encrypt($pt, Crypto::CIPHER_METHOD_AES_128_CBC, $mkey->getKey(), OPENSSL_RAW_DATA, $iv);
        if ($ct_data === FALSE)
            throw new EncryptExceptoin("Key encryption error. Cipher method: " . Crypto::CIPHER_METHOD_AES_128_CBC);
        
        $ct = $rsec . $ct_data;
        
        return $ct;
    }
    
    public static function decrypt($mkey, $ct)
    {
        $rsec = substr($ct, 0, self::RANDOM_SIZE);
        $ct_data = substr($ct, self::RANDOM_SIZE, strlen($ct) - self::RANDOM_SIZE);
        $iv = str_pad($rsec, Crypto::CIPHER_IV_SIZE, "\x00");
        
        $pt = openssl_decrypt($ct_data, Crypto::CIPHER_METHOD_AES_128_CBC, $mkey->getKey(), OPENSSL_RAW_DATA, $iv);
        
        if ($pt === FALSE)
            throw new DecryptException("Key decryption error. Cipher method: " . Crypto::CIPHER_METHOD_AES_128_CBC);
        
        
        return $pt;
    }
    
    public static function wrap($mkey, $dkey)
    {
        $ct = openssl_encrypt(
            $dkey, 
            Crypto::CIPHER_METHOD_AES_128_CBC, 
            $mkey->getKey(),
            OPENSSL_RAW_DATA|OPENSSL_ZERO_PADDING,
            self::ZERO_IV);
        if($ct === FALSE){
            throw new EncryptExceptoin("Key encryption error. Cipher method: " . Crypto::CIPHER_METHOD_AES_128_CBC);
        }
        
        return $ct;
    }
    
    public static function unwrap($mkey, $ct)
    {
        $pt = openssl_decrypt(
            $ct, 
            Crypto::CIPHER_METHOD_AES_128_CBC, 
            $mkey->getKey(), 
            OPENSSL_RAW_DATA|OPENSSL_ZERO_PADDING, 
            self::ZERO_IV);
        if($pt === FALSE){
            throw new DecryptException("Key decryption error, Cipher method: " . Crypto::CIPHER_METHOD_AES_128_CBC);
        }
        
        return $pt;
    }
}