Secure communication PHP (phpseclib) and C# (Unity 3D)

Question

im trying to establish secure RSA connection between PHP server and Unity 3D game (in Web Player). At the end of process $rsa->decrypt() return "false" :-(

Server generate RSA keys and send public key to Unity:

$rsa = new Crypt_RSA();
$rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1);
$rsa->setPrivateKeyFormat(CRYPT_RSA_PRIVATE_FORMAT_PKCS1);
$rsa->setPublicKeyFormat(CRYPT_RSA_PUBLIC_FORMAT_PKCS1);

$keys = $rsa->createKey(512);
extract($keys);
$rsa->loadKey($publickey);
$_SESSION["privatekey"] = $privatekey;

$this->payload->Modulus = base64_encode($rsa->modulus);
$this->payload->Exponent = base64_encode($rsa->publicExponent);

This generate JSON:

{"Modulus":"MTE5MjcyOTYyNjQzMTIzODQ1MTI4MjE2ODA3OTY2MDE5MDQwODQ1NTc0MDIzMDI0NDQ5MjAzMDY4NDgxNTkyNzk5MTc0MzYxMzI4MDA3Njk0MjI4NjAyMzAwODA4MDI5MzkwOTk2MjUyMTg5OTkwNDgwNzg3MDcwMjk4MjkxMjcxNjQ1NzMzNDg0MTcxNTc0MDM3ODM0NjE3ODE=","Exponent":"NjU1Mzc="}

Unity ENCODER:

var N = JSON.Parse (generatedJSON); //im using SimpleJSON library
var publicKey = new RSAParameters ();
publicKey.Modulus = Convert.FromBase64String(N ["Modulus"].Value);
publicKey.Exponent = Convert.FromBase64String(N ["Exponent"].Value);

var csp = new RSACryptoServiceProvider(512);
csp.ImportParameters(publicKey);
var plainTextData = "Hello Wordl"; //here come AES key generator (not implemented yet)
var bytesPlainTextData = System.Text.Encoding.Unicode.GetBytes(plainTextData);
var bytesCypherText = csp.Encrypt(bytesPlainTextData, false);
var cypherText = Convert.ToBase64String(bytesCypherText);

Unity response:

Nqsno9tTXWr4UfwoXQcHwzwnusvdKWpVGoakSsVECh3lH/3bNaPKY9LzZ9iZIs8RI9e5EI+GvegnxrW5xoqnyrDHbF8AuWh9Hndnn0OS5SV/kiYeBT6Wn9pxwjq5MoixM3geushHpvGTDQV0NOLcsXTdv8tG0CvFZip31GpMp9C/OalxolpaUvk65YBJ0dJcyNiuD08PQJAupJXKnVgfLZ0i1GrjQ7guHO6OmEUKDyQcZ5Sf/6yJry3Mhv2R4ioR/jU+mL4tLKuix5+/XKmBjg==

And server DECODER:

$rsa = new Crypt_RSA();
$rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1);
$rsa->setPrivateKeyFormat(CRYPT_RSA_PRIVATE_FORMAT_PKCS1);
$rsa->setPublicKeyFormat(CRYPT_RSA_PUBLIC_FORMAT_PKCS1);

$rsa->loadKey($_SESSION["privatekey"]);
$message = $_POST["unityResponse"];
$ciphertext = base64_decode($message);

$this->payload->message = $rsa->decrypt($ciphertext);

Return "Decryption error in..." :(

I think general problem is in C#... Can you help me?

Answer 1

SOLVED!

By another way - XML key format

Server code:

$rsa = new Crypt_RSA();
$rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1);
$rsa->setPrivateKeyFormat(CRYPT_RSA_PRIVATE_FORMAT_XML);
$rsa->setPublicKeyFormat(CRYPT_RSA_PUBLIC_FORMAT_XML);

$keys = $rsa->createKey(1024);
extract($keys);
$rsa->loadKey($publickey);
$_SESSION["privatekey"] = $privatekey;
$this->payload->publickey = $publickey;

Generate JSON:

{"publickey":"<RSAKeyValue>\r\n  <Modulus>sCL/O7uUl4T32nUxZhKj1svDG88k4jkGsh/7IiFX/kTbj3mXmtYPLn5xTyLxEt9FxA/aoVxBmh1k7wA7lvcu5z4Avw6+AA/j793iDEhGdfvmXmHxm05xkjYO+LZ449YGDst9DUDO8SDA948Rld+eA187d/nhVPPAmun7RbLXBrs=</Modulus>\r\n  <Exponent>AQAB</Exponent>\r\n</RSAKeyValue>"}

Unity Web Player code:

var N = JSON.Parse (generatedJSON);
var csp = new RSACryptoServiceProvider(1024);
csp.FromXmlString (N ["publickey"]);
var plainTextData = "Hello from Web Player";
var bytesPlainTextData = System.Text.Encoding.Unicode.GetBytes(plainTextData);
var bytesCypherText = csp.Encrypt(bytesPlainTextData, false);
var cypherText = Convert.ToBase64String(bytesCypherText);

And finally Server Decryption:

$rsa = new Crypt_RSA();
$rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1);
$rsa->setPrivateKeyFormat(CRYPT_RSA_PRIVATE_FORMAT_XML);
$rsa->setPublicKeyFormat(CRYPT_RSA_PUBLIC_FORMAT_XML);

$rsa->loadKey($_SESSION["privatekey"]);
$cypherText= $_POST["cypherText"];
$bytesCipherText = base64_decode($message);
$this->payload->encrypted = $rsa->decrypt($bytesCipherText);

And you get JSON:

{"message":"Hello from Web Player"}

Thanks for perfect phpsec library! Its epic!