Secure token created in node different from .net - node.js

Question

I'm trying to implement reCaptcha Secure Tokens in nodejs.
Looked at the examples made in Java and in .NET and created this version for node:
exports.getSecureToken = function() {
var algorithm = 'aes-128-ecb';
var tokenObj = { session_id: 'ab0069ec-3c2c-436c-868b-43c7a10db229'/*uuid.v4()*/, ts_ms: 1446560931992/*(new Date()).getTime()*/ };
var text = JSON.stringify(tokenObj);
var shaHash = new Buffer(crypto.createHash('sha1').update('6LeyNOTTVALIDH2RLNaivqrrpm2zh56Y3uHqOjFO'/*config.reCAPTCHASecret*/).digest('hex'), 'hex');
var key = shaHash.slice(0, 16);
var cipher = crypto.createCipher(algorithm, key, key);
var encryptedToken = cipher.update(text, 'utf8', 'base64') + cipher.final('base64');
var result = encryptedToken.replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '');
return result;
};
Problem is that in .NET I get a token that works (using the right key not included in the post), but in node I get a different token for the same input, and it doesn't works:
.NET - LhPTUELia5vc0X6aDGDtqpsbmB7oqm6vUnzk5BL2auactYXRU5TEUzML8gZ_JubXG07rvJxk1Sb5_a-wqVUGEf_UuO1gGi-WO83yJHOxnjI
node - EGr7drd1JEylwzLGakZ6dpPRSf2nFdpzHOrJlLZlyHYmVRj5obAw7WjPt4W5l0vsywNEqCQ-2_d7qIZOMiOedianfBrQPOBaOmmq44IOB8Q
I got to see that key and input are the same (in .NET and node) right at the moment before encryption, so the problem must(?) be the cipher, any clues?
.NET code for reference:
public static void Main(string[] args)
{
//Your code goes here
Console.WriteLine(EncryptJsonToken(GetJsonToken()));
}
public static string GetJsonToken()
{
//Example: {"session_id": e6e9c56e-a7da-43b8-89fa-8e668cc0b86f,"ts_ms":1421774317718}
string jsonRequest = "{" + string.Format("\"session_id\": {0},\"ts_ms\":{1}", "ab0069ec-3c2c-436c-868b-43c7a10db229", 1446560931992) + "}";
return jsonRequest;
}
public static byte[] getKey()
{
string secretKey = "6LeyNOTTVALIDH2RLNaivqrrpm2zh56Y3uHqOjFO";
SHA1 sha = SHA1.Create();
byte[] dataToHash = Encoding.UTF8.GetBytes(secretKey);
byte[] shaHash = sha.ComputeHash(dataToHash);
byte[] first16OfHash = new byte[16];
Array.Copy(shaHash, first16OfHash, 16);
return first16OfHash;
}
public static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)
{
// Check arguments.
if (plainText == null || plainText.Length <= 0)
throw new ArgumentNullException("plainText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("IV");
byte[] encrypted;
// Create an AesManaged object
// with the specified key and IV.
using (AesManaged aesAlg = new AesManaged())
{
aesAlg.Key = Key;
aesAlg.IV = IV;
aesAlg.Padding = PaddingMode.PKCS7;
aesAlg.Mode = CipherMode.ECB;
// Create a decrytor to perform the stream transform.
ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
// Create the streams used for encryption.
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
//Write all data to the stream.
swEncrypt.Write(plainText);
}
encrypted = msEncrypt.ToArray();
}
}
}
// Return the encrypted bytes from the memory stream.
return encrypted;
}
public static string EncryptJsonToken(string jsonToken)
{
byte[] encrypted = EncryptStringToBytes_Aes(jsonToken, getKey(), getKey());
//Base64 encode the encrypted data
//Also applys the URL variant of base64 encoding, unfortunately the HttpServerUtility.UrlTokenEncode(encrypted) seems to truncate the last value from the string so we can't use it?
return Convert.ToBase64String(encrypted, Base64FormattingOptions.None).Replace("=", String.Empty).Replace('+', '-').Replace('/', '_');
}
To debug in .NET: DEMO

Answer 1

You have two problems:
You're using JSON.stringify() to produce a valid JSON string, but the GetJsonToken() method in the C# code doesn't produce a valid JSON string. There are " missing for the UUID and there is a space between the session_id key and its value for some reason. You have to reflect those differences in JavaScript:
var uuidToken = "ab0069ec-3c2c-436c-868b-43c7a10db229";
var time = 1446560931992;
var text = "{\"session_id\": "+uuidToken+",\"ts_ms\":"+time+"}";
There is no such function crypto.createCipher(algorithm, key, key). There is however crypto.createCipheriv(algorithm, key, iv). createCipher(algorithm, password) can be used if one has a password instead of a key which you don't have. Since there is no IV for ECB mode, you can pass in an empty (binary) string as the IV.
Full code:
var crypto = require("crypto");
var algorithm = 'aes-128-ecb';
var uuidToken = "ab0069ec-3c2c-436c-868b-43c7a10db229";
var time = 1446560931992;
var text = "{\"session_id\": "+uuidToken+",\"ts_ms\":"+time+"}";
console.log("Token: " + text);
var shaHash = crypto.createHash('sha1').update('6LeyNOTTVALIDH2RLNaivqrrpm2zh56Y3uHqOjFO').digest();
var key = shaHash.slice(0, 16);
var cipher = crypto.createCipheriv(algorithm, key, "");
var encryptedToken = cipher.update(text, 'utf8', 'base64') + cipher.final('base64');
var result = encryptedToken.replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '');
console.log("result: " + result);
console.log("expected: LhPTUELia5vc0X6aDGDtqpsbmB7oqm6vUnzk5BL2auactYXRU5TEUzML8gZ_JubXG07rvJxk1Sb5_a-wqVUGEf_UuO1gGi-WO83yJHOxnjI");
Output:
Token: {"session_id": ab0069ec-3c2c-436c-868b-43c7a10db229,"ts_ms":1446560931992}
result: LhPTUELia5vc0X6aDGDtqpsbmB7oqm6vUnzk5BL2auactYXRU5TEUzML8gZ_JubXG07rvJxk1Sb5_a-wqVUGEf_UuO1gGi-WO83yJHOxnjI
expected: LhPTUELia5vc0X6aDGDtqpsbmB7oqm6vUnzk5BL2auactYXRU5TEUzML8gZ_JubXG07rvJxk1Sb5_a-wqVUGEf_UuO1gGi-WO83yJHOxnjI