generate HMAC-SHA1 in C#

Question

I am trying to make use of a REST API using C#.

The API creator has provided below pseudo code for hmac creation.

var key1 = sha1(body);
var key2 = key1         


        

Answer 1

Direct mapping of above code to C# would be something like:

static string ComputeSignature(byte[] body, byte[] secret) {
    using (var sha1 = SHA1.Create())
    {
        var key1 = sha1.ComputeHash(body);
        var key2 = key1.Concat(secret).ToArray();
        var key3 = sha1.ComputeHash(key2);
        return Convert.ToBase64String(key3);
    }
}

If you have request body as a string, convert it to byte array using proper encoding, for example:

var body = Encoding.UTF8.GetBytes(bodyAsString);

If you have your secret as string - that depends on how api developer expects it to be converted to byte array. Most likely it's already HEX or base64-encoded string.