Mix: Integrate cover traffic to mix service (#920)

nodes/nomos-node/config.yaml

@@ -62,6 +62,13 @@ mix:
       num_mix_layers: 1
     temporal_processor:
       max_delay_seconds: 5
+  cover_traffic:
+    epoch_duration:
+      secs: 432000
+      nanos: 0
+    slot_duration:
+      secs: 20
+      nanos: 0
   membership:
     - address: /ip4/127.0.0.1/udp/3001/quic-v1
       public_key: [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]

nomos-mix/core/src/cover_traffic.rs

@@ -122,7 +122,7 @@ mod tests {
     #[test]
     fn test_ticket() {
         generate_ticket(10u32.to_be_bytes(), 1123, 0);
-        for i in (0..1u32) {
+        for i in 0..1u32 {
             let slots = select_slot(i.to_be_bytes(), 1234, 100, 21600, winning_probability(1));
             println!("slots = {slots:?}");
         }

nomos-mix/core/src/membership.rs

@@ -9,6 +9,7 @@ where
     M: MixMessage,
 {
     remote_nodes: Vec<Node<M::PublicKey>>,
+    local_node: Node<M::PublicKey>,
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -22,10 +23,20 @@ where
     M: MixMessage,
     M::PublicKey: PartialEq,
 {
-    pub fn new(mut nodes: Vec<Node<M::PublicKey>>, local_public_key: M::PublicKey) -> Self {
+    pub fn new(nodes: Vec<Node<M::PublicKey>>, local_public_key: M::PublicKey) -> Self {
-        nodes.retain(|node| node.public_key != local_public_key);
+        let mut remote_nodes = Vec::with_capacity(nodes.len() - 1);
+        let mut local_node = None;
+        nodes.into_iter().for_each(|node| {
+            if node.public_key == local_public_key {
+                local_node = Some(node);
+            } else {
+                remote_nodes.push(node);
+            }
+        });
+
         Self {
-            remote_nodes: nodes,
+            remote_nodes,
+            local_node: local_node.expect("Local node not found"),
         }
     }
 
@@ -36,4 +47,12 @@ where
     ) -> Vec<&Node<M::PublicKey>> {
         self.remote_nodes.choose_multiple(rng, amount).collect()
     }
+
+    pub fn local_node(&self) -> &Node<M::PublicKey> {
+        &self.local_node
+    }
+
+    pub fn size(&self) -> usize {
+        self.remote_nodes.len() + 1
+    }
 }

nomos-services/data-availability/tests/src/common.rs

@@ -229,6 +229,10 @@ pub fn new_node(
                         max_delay_seconds: 2,
                     },
                 },
+                cover_traffic: nomos_mix_service::CoverTrafficExtSettings {
+                    epoch_duration: Duration::from_secs(432000),
+                    slot_duration: Duration::from_secs(20),
+                },
                 membership: mix_config.membership.clone(),
             },
             da_network: DaNetworkConfig {

nomos-services/mix/src/lib.rs

@@ -6,15 +6,18 @@ use backends::MixBackend;
 use futures::StreamExt;
 use network::NetworkAdapter;
 use nomos_core::wire;
-use nomos_mix::membership::{Membership, Node};
-use nomos_mix::message_blend::crypto::CryptographicProcessor;
 use nomos_mix::message_blend::temporal::TemporalScheduler;
+use nomos_mix::message_blend::{crypto::CryptographicProcessor, CryptographicProcessorSettings};
 use nomos_mix::message_blend::{MessageBlendExt, MessageBlendSettings};
 use nomos_mix::persistent_transmission::{
     PersistentTransmissionExt, PersistentTransmissionSettings, PersistentTransmissionStream,
 };
 use nomos_mix::MixOutgoingMessage;
-use nomos_mix_message::mock::MockMixMessage;
+use nomos_mix::{
+    cover_traffic::{CoverTraffic, CoverTrafficSettings},
+    membership::{Membership, Node},
+};
+use nomos_mix_message::{mock::MockMixMessage, MixMessage};
 use nomos_network::NetworkService;
 use overwatch_rs::services::{
     handle::ServiceStateHandle,
@@ -127,12 +130,22 @@ where
             ChaCha12Rng::from_entropy(),
         );
         let mut blend_messages = backend.listen_to_incoming_messages().blend(
-            mix_config.message_blend,
+            mix_config.message_blend.clone(),
             membership.clone(),
             temporal_scheduler,
             ChaCha12Rng::from_entropy(),
         );
 
+        // tier 3 cover traffic
+        let mut cover_traffic: CoverTraffic<_, _, MockMixMessage> = CoverTraffic::new(
+            mix_config.cover_traffic.cover_traffic_settings(
+                &membership,
+                &mix_config.message_blend.cryptographic_processor,
+            ),
+            mix_config.cover_traffic.epoch_stream(),
+            mix_config.cover_traffic.slot_stream(),
+        );
+
         // local messages, are bypassed and send immediately
         let mut local_messages = service_state
             .inbound_relay
@@ -162,23 +175,17 @@ where
                                     network_adapter.broadcast(msg.message, msg.broadcast_settings).await;
                                 },
                                 _ => {
-                                    tracing::error!("unrecognized message from mix backend");
+                                    tracing::debug!("unrecognized message from mix backend");
                                 }
                             }
                         }
                     }
                 }
+                Some(msg) = cover_traffic.next() => {
+                    Self::wrap_and_send_to_persistent_transmission(msg, &mut cryptographic_processor, &persistent_sender);
+                }
                 Some(msg) = local_messages.next() => {
-                    match cryptographic_processor.wrap_message(&msg) {
+                    Self::wrap_and_send_to_persistent_transmission(msg, &mut cryptographic_processor, &persistent_sender);
-                        Ok(wrapped_message) => {
-                            if let Err(e) = persistent_sender.send(wrapped_message) {
-                                tracing::error!("Error sending message to persistent stream: {e}");
-                            }
-                        }
-                        Err(e) => {
-                            tracing::error!("Failed to wrap message: {:?}", e);
-                        }
-                    }
                 }
                 Some(msg) = lifecycle_stream.next() => {
                     if Self::should_stop_service(msg).await {
@@ -214,6 +221,23 @@ where
             }
         }
     }
+
+    fn wrap_and_send_to_persistent_transmission(
+        message: Vec<u8>,
+        cryptographic_processor: &mut CryptographicProcessor<ChaCha12Rng, MockMixMessage>,
+        persistent_sender: &mpsc::UnboundedSender<Vec<u8>>,
+    ) {
+        match cryptographic_processor.wrap_message(&message) {
+            Ok(wrapped_message) => {
+                if let Err(e) = persistent_sender.send(wrapped_message) {
+                    tracing::error!("Error sending message to persistent stream: {e}");
+                }
+            }
+            Err(e) => {
+                tracing::error!("Failed to wrap message: {:?}", e);
+            }
+        }
+    }
 }
 
 #[derive(Serialize, Deserialize, Clone, Debug)]
@@ -221,11 +245,64 @@ pub struct MixConfig<BackendSettings> {
     pub backend: BackendSettings,
     pub message_blend: MessageBlendSettings<MockMixMessage>,
     pub persistent_transmission: PersistentTransmissionSettings,
+    pub cover_traffic: CoverTrafficExtSettings,
     pub membership: Vec<
         Node<<nomos_mix_message::mock::MockMixMessage as nomos_mix_message::MixMessage>::PublicKey>,
     >,
 }
 
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct CoverTrafficExtSettings {
+    pub epoch_duration: Duration,
+    pub slot_duration: Duration,
+}
+
+impl CoverTrafficExtSettings {
+    fn cover_traffic_settings(
+        &self,
+        membership: &Membership<MockMixMessage>,
+        cryptographic_processor_settings: &CryptographicProcessorSettings<
+            <MockMixMessage as MixMessage>::PrivateKey,
+        >,
+    ) -> CoverTrafficSettings {
+        CoverTrafficSettings {
+            node_id: membership.local_node().public_key,
+            number_of_hops: cryptographic_processor_settings.num_mix_layers,
+            slots_per_epoch: self.slots_per_epoch(),
+            network_size: membership.size(),
+        }
+    }
+
+    fn slots_per_epoch(&self) -> usize {
+        (self.epoch_duration.as_secs() as usize)
+            .checked_div(self.slot_duration.as_secs() as usize)
+            .expect("Invalid epoch & slot duration")
+    }
+
+    fn epoch_stream(
+        &self,
+    ) -> futures::stream::Map<
+        futures::stream::Enumerate<IntervalStream>,
+        impl FnMut((usize, time::Instant)) -> usize,
+    > {
+        IntervalStream::new(time::interval(self.epoch_duration))
+            .enumerate()
+            .map(|(i, _)| i)
+    }
+
+    fn slot_stream(
+        &self,
+    ) -> futures::stream::Map<
+        futures::stream::Enumerate<IntervalStream>,
+        impl FnMut((usize, time::Instant)) -> usize,
+    > {
+        let slots_per_epoch = self.slots_per_epoch();
+        IntervalStream::new(time::interval(self.slot_duration))
+            .enumerate()
+            .map(move |(i, _)| i % slots_per_epoch)
+    }
+}
+
 impl<BackendSettings> MixConfig<BackendSettings> {
     fn membership(&self) -> Membership<MockMixMessage> {
         // We use private key as a public key because the `MockMixMessage` doesn't differentiate between them.

tests/src/nodes/executor.rs

@@ -166,6 +166,10 @@ pub fn create_executor_config(config: GeneralConfig) -> Config {
                     max_delay_seconds: 2,
                 },
             },
+            cover_traffic: nomos_mix_service::CoverTrafficExtSettings {
+                epoch_duration: Duration::from_secs(432000),
+                slot_duration: Duration::from_secs(20),
+            },
             membership: config.mix_config.membership,
         },
         cryptarchia: CryptarchiaSettings {

tests/src/nodes/validator.rs

@@ -252,6 +252,10 @@ pub fn create_validator_config(config: GeneralConfig) -> Config {
                     max_delay_seconds: 2,
                 },
             },
+            cover_traffic: nomos_mix_service::CoverTrafficExtSettings {
+                epoch_duration: Duration::from_secs(432000),
+                slot_duration: Duration::from_secs(20),
+            },
             membership: config.mix_config.membership,
         },
         cryptarchia: CryptarchiaSettings {