Verifying X-Slack-Signature from the SlackAPI

verification.cs

// I had some issues with implementing the verification for the Slack Signature in the POST requests. Turns out I didn't remove the '-' in my Hash. This method works in my case.
// Copied from https://github.com/microsoft/botbuilder-dotnet/blob/master/libraries/Adapters/Microsoft.Bot.Builder.Adapters.Slack/SlackClientWrapper.cs#L673 
        public bool VerifySignature(HttpListenerRequest request, string body)
        {
            if (request == null || string.IsNullOrWhiteSpace(body))
            {
                return false;
            }

            var timestamp = request.Headers["X-Slack-Request-Timestamp"];

            object[] signature = { "v0", timestamp.ToString(), body };

            var baseString = string.Join(":", signature);
            // Replace Config.SlackSigningSecret with your variable 
            using (var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(Config.SlackSigningSecrett)))
            {
                var hashArray = hmac.ComputeHash(Encoding.UTF8.GetBytes(baseString));

                var hash = string.Concat("v0=", BitConverter.ToString(hashArray).Replace("-", string.Empty)).ToUpperInvariant();

                var retrievedSignature = request.Headers["X-Slack-Signature"].ToString().ToUpperInvariant();

                return hash == retrievedSignature;
            }
        }