Create C# generated HMAC hash in Javascript

Question

I have C# function below;

private string GetEncyptionData(string encryptionKey)
    {
        string hashString = string.Format("{{timestamp:{0},client_id:{1}}}", Timestamp, ClientId);
        HMAC hmac = HMAC.Create();
        hmac.Key = Guid.Parse(encryptionKey).ToByteArray();
        byte[] hash = hmac.ComputeHash(Encoding.UTF8.GetBytes(hashString));
        string encData = Convert.ToBase64String(hash);
        return encData;
    }

I am trying to convert this code in Javascript. I found this library as helper.

Here is code I am using;

 <script>
            var timestamp = 1424890904;
            var client_id = "496ADAA8-36D0-4B65-A9EF-EE4E3659910D";
            var EncryptionKey = "E69B1B7D-8DFD-4DEA-824A-8D43B42BECC5";

            var message = "{timestamp:{0},client_id:{1}}".replace("{0}", timestamp).replace("{1}", client_id);

            var hash = CryptoJS.HmacSHA1(message, EncryptionKey);
            var hashInBase64 = CryptoJS.enc.Base64.stringify(hash);       

             alert(hashInBase64);
        </script>

but code above is not generating same output from C# code. How can I achieve it in Javascript?

Are you 100% sure encryption key and timestamp are exact? That's what often tripped me up in the past.... Also compare values before and after the hash and again before and after the base 64 conversion to see where the differences may lie. — Brian Mains
– Brian Mains, Commented Feb 25, 2015 at 20:17

Joe Enos · Accepted Answer · 2015-02-25 20:46:37Z

3

Your issue is due to your key. In C#, you're passing in a 16-byte array as the key. In CryptoJS, you're passing in a string which CryptoJS is interpreting as a passphrase, so it's going to generate a totally different key from that.

EDIT: Here's how to get the correct key in javascript:

If you convert your 16-byte key to Base64, in javascript you can do the following. It will generate a WordArray as the key, and use that key to generate your hash.

var keyBase64 = "eFY0EiMBZ0UBI0VniRI0Vg==";
var key = CryptoJS.enc.Base64.parse(keyBase64);
var hash = CryptoJS.HmacSHA1("Hello", key);
var hashInBase64 = CryptoJS.enc.Base64.stringify(hash); 
console.log(hashInBase64);

edited Feb 25, 2015 at 20:46

answered Feb 25, 2015 at 20:28

Joe Enos

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2 Comments

Teoman shipahi Over a year ago

Simply works great. I wish I would have Javascript equivalent of Guid.Parse(encryptionKey).ToByteArray(); but anyway I will convert it manually for now.

Joe Enos Over a year ago

CryptoJS might have something that can do it - I didn't dig too much into their helper libraries.

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