First commit that builds.

code/MessengerBroker/Handlers/AuthHandler.cs

@@ -0,0 +1,28 @@
+namespace MessengerBroker.Handlers
+{
+    public class AuthHandler
+    {
+        private readonly Settings settings;
+
+        public AuthHandler(Settings settings)
+        {
+            this.settings = settings;
+        }
+
+        public Guid? Auth(HttpContext context)
+        {
+            var authHeader = context.Request.Headers["Authorization"].ToString();
+
+            if (!string.IsNullOrEmpty(authHeader) && authHeader.StartsWith("Bearer "))
+            {
+                var token = authHeader.Substring("Bearer ".Length).Trim();
+                if (Guid.TryParse(token, out Guid brokerId) && this.settings.Slaves.Any(x => x.BrokerId == brokerId))
+                {
+                    return brokerId;
+                }
+            }
+
+            return null;
+        }
+    }
+}