Add a stream that will only serve valid sigs

src/Nostr.Client/Client/NostrClientStreams.cs

@@ -15,10 +15,18 @@ public class NostrClientStreams
         internal readonly Subject<NostrRawResponse> UnknownRawSubject = new();
 
         /// <summary>
-        /// Requested Nostr events
+        /// Requested Nostr events (includes all events, signature not validated)
         /// </summary>
         public IObservable<NostrEventResponse> EventStream => EventSubject.AsObservable();
 
+        /// <summary>
+        /// Requested Nostr events with valid signatures only.
+        /// Events with invalid or missing signatures are filtered out.
+        /// </summary>
+        public IObservable<NostrEventResponse> ValidEventStream => EventSubject
+            .AsObservable()
+            .Where(x => x.IsSignatureValid);
+
         /// <summary>
         /// Human-readable messages
         /// </summary>

src/Nostr.Client/Responses/NostrEventResponse.cs

@@ -14,5 +14,12 @@ public class NostrEventResponse : NostrResponse
         [ArrayProperty(2)]
         [JsonConverter(typeof(NostrEventConverter))]
         public NostrEvent? Event { get; init; }
+
+        /// <summary>
+        /// Check if the event signature is valid.
+        /// Returns false if event is null or signature verification fails.
+        /// </summary>
+        [JsonIgnore]
+        public bool IsSignatureValid => Event?.IsSignatureValid() ?? false;
     }
 }