Question

Please advise for encryption in flash that can be decrypted easily in PHP.

Answer 1

For Flash you can http://code.google.com/p/as3crypto/ it supports

• RSA
• DES
• AES
• Blowfish –
• MD5
• SHA
• X509
• RC4

PHP you can use mycrypt http://www.php.net/manual/en/mcrypt.examples.php RSA, DES, AES, Blowfish, MD5, SHA, X509, RC4 all the above encryption also supported

Flash Class Example

package
{
        import flash.display.Sprite;
        import flash.utils.ByteArray;

        import com.hurlant.crypto.symmetric.ICipher;
        import com.hurlant.crypto.symmetric.IVMode;
        import com.hurlant.crypto.symmetric.IMode;
        import com.hurlant.crypto.symmetric.NullPad;
        import com.hurlant.crypto.symmetric.PKCS5;
        import com.hurlant.crypto.symmetric.IPad;
        import com.hurlant.util.Base64;
        import com.hurlant.util.Hex;
        import com.hurlant.crypto.Crypto;

        public class CryptoCode extends Sprite
        {
                private var type:String='simple-des-ecb';
                private var key:ByteArray;

                public function CryptoCode()
                {
                        init();
                }

                private function init():void
                {
                        key = Hex.toArray(Hex.fromString('TESTTEST'));// can only be 8 characters long

                        trace(encrypt('TEST TEST'));
                        trace(decrypt(encrypt('TEST TEST'));
                }

                private function encrypt(txt:String = ''):String
                {
                        var data:ByteArray = Hex.toArray(Hex.fromString(txt));

                        var pad:IPad = new PKCS5;
                        var mode:ICipher = Crypto.getCipher(type, key, pad);
                        pad.setBlockSize(mode.getBlockSize());
                        mode.encrypt(data);
                        return Base64.encodeByteArray(data);
                }
                private function decrypt(txt:String = ''):String
                {
                        var data:ByteArray = Base64.decodeToByteArray(txt);
                        var pad:IPad = new PKCS5;
                        var mode:ICipher = Crypto.getCipher(type, key, pad);
                        pad.setBlockSize(mode.getBlockSize());
                        mode.decrypt(data);
                        return Hex.toString(Hex.fromArray(data));
                }
        }

}

PHP Class Example

class Crypt
{
        var $key = NULL;
        var $iv = NULL;
        var $iv_size = NULL;

        function Crypt()
        {
                $this->init();
        }

        function init($key = "")
        {
                $this->key = ($key != "") ? $key : "";

                $this->algorithm = MCRYPT_DES;
                $this->mode = MCRYPT_MODE_ECB;

                $this->iv_size = mcrypt_get_iv_size($this->algorithm, $this->mode);
                $this->iv = mcrypt_create_iv($this->iv_size, MCRYPT_RAND);
        }

        function encrypt($data)
        {
                $size = mcrypt_get_block_size($this->algorithm, $this->mode);
                $data = $this->pkcs5_pad($data, $size);
                return base64_encode(mcrypt_encrypt($this->algorithm, $this->key, $data, $this->mode, $this->iv));
        }

        function decrypt($data)
        {
                return $this->pkcs5_unpad(rtrim(mcrypt_decrypt($this->algorithm, $this->key, base64_decode($data), $this->mode, $this->iv)));
        }

        function pkcs5_pad($text, $blocksize)
        {
                $pad = $blocksize - (strlen($text) % $blocksize);
                return $text . str_repeat(chr($pad), $pad);
        }

        function pkcs5_unpad($text)
        {
                $pad = ord($text{strlen($text)-1});
                if ($pad > strlen($text)) return false;
                if (strspn($text, chr($pad), strlen($text) - $pad) != $pad) return false;
                return substr($text, 0, -1 * $pad);
        }
}

Usage flash

// instance of crypto class
 private var _crypto : CryptoCode;
 public var myLoader : URLLoader;

// create instance with encryption key
 _crypto = new CryptoCode("PASSWORD");

// send crypted string to php script
 var variables : URLVariables = new URLVariables();
 variables.message = _crypto.encrypt(tosend_in.text);

// create request with POST method
 var request : URLRequest = new URLRequest("http://www.lecrabe.net/wordpress/demo/crypt/scripts/testcrypto.php");
 request.method = URLRequestMethod.POST;
 request.data = variables;

 // send request
 myLoader.load(request);

Usage PHP

include_once "lib/cryptlib.php";

// init a new instance of Crypto Class
$crypto = new Crypt;

// init with the encryption key
$result = $crypto->init("PASSWORD");

// get the POST data
$messagefromflash = $_POST ["message"];

// decrypt data
$decrypted_messagefromflash = $crypto->decrypt(utf8_decode($messagefromflash));