@@ -0,0 +1,16 @@
+package auth
+
+// Authenticator callback checks given auth primitives (i.e. customer identity signature / node's sessionId)
+type Authenticator func(username, password string) (bool, error)
+
+// NewAuthenticator returns Authenticator callback
+func NewAuthenticator() Authenticator {
+	// TODO: implement
+	return func(username, password string) (bool, error) {
+		if username == "bad" {
+			return false, nil
+		}
+
+		return true, nil
+	}
+}
2 names are the same. What about `AuthChecker` or `AuthService`?