use exit==destination approach for mix for better anonymity

Makefile

@@ -143,6 +143,9 @@ ifeq ($(USE_LIBBACKTRACE), 0)
 NIM_PARAMS := $(NIM_PARAMS) -d:disable_libbacktrace
 endif
 
+# enable experimental exit is dest feature in libp2p mix
+NIM_PARAMS := $(NIM_PARAMS) -d:libp2p_mix_experimental_exit_is_dest 
+
 libbacktrace:
 	+ $(MAKE) -C vendor/nim-libbacktrace --no-print-directory BUILD_CXX_LIB=0
 

apps/chat2mix/chat2mix.nim

@@ -82,6 +82,8 @@ type
   PrivateKey* = crypto.PrivateKey
   Topic* = waku_core.PubsubTopic
 
+const MinMixNodePoolSize = 4
+
 #####################
 ## chat2 protobufs ##
 #####################
@@ -592,19 +594,20 @@ proc processInput(rfd: AsyncFD, rng: ref HmacDrbgContext) {.async.} =
 
   node.peerManager.addServicePeer(servicePeerInfo, WakuLightpushCodec)
   node.peerManager.addServicePeer(servicePeerInfo, WakuPeerExchangeCodec)
+  #node.peerManager.addServicePeer(servicePeerInfo, WakuRendezVousCodec)
 
   # Start maintaining subscription
   asyncSpawn maintainSubscription(
     node, pubsubTopic, conf.contentTopic, servicePeerInfo, false
   )
   echo "waiting for mix nodes to be discovered..."
   while true:
-    if node.getMixNodePoolSize() >= 3:
+    if node.getMixNodePoolSize() >= MinMixNodePoolSize:
       break
     discard await node.fetchPeerExchangePeers()
     await sleepAsync(1000)
 
-  while node.getMixNodePoolSize() < 3:
+  while node.getMixNodePoolSize() < MinMixNodePoolSize:
     info "waiting for mix nodes to be discovered",
       currentpoolSize = node.getMixNodePoolSize()
     await sleepAsync(1000)

examples/lightpush_mix/lightpush_publisher_mix.nim

@@ -144,7 +144,7 @@ proc setupAndPublish(rng: ref HmacDrbgContext, conf: LightPushMixConf) {.async.}
       conn = connOpt.get()
     else:
       conn = node.wakuMix.toConnection(
-        MixDestination.init(dPeerId, pxPeerInfo.addrs[0]), # destination lightpush peer
+        MixDestination.exitNode(dPeerId), # destination lightpush peer
         WakuLightPushCodec, # protocol codec which will be used over the mix connection
         MixParameters(expectReply: Opt.some(true), numSurbs: Opt.some(byte(1))),
           # mix parameters indicating we expect a single reply
@@ -163,6 +163,9 @@ proc setupAndPublish(rng: ref HmacDrbgContext, conf: LightPushMixConf) {.async.}
       ephemeral: true, # tell store nodes to not store it
       timestamp: getNowInNanosecondTime(),
     ) # current timestamp
+    let res = await node.wakuLightpushClient.publishWithConn(
+      LightpushPubsubTopic, message, conn, dPeerId
+    )
 
     let startTime = getNowInNanosecondTime()
 

simulations/mixnet/config.toml

@@ -1,6 +1,6 @@
 log-level = "INFO"
 relay = true
-#mix = true
+mix = true
 filter = true
 store = false
 lightpush = true
@@ -18,7 +18,7 @@ num-shards-in-network = 1
 shard = [0]
 agent-string = "nwaku-mix"
 nodekey = "f98e3fba96c32e8d1967d460f1b79457380e1a895f7971cecc8528abe733781a"
-#mixkey = "a87db88246ec0eedda347b9b643864bee3d6933eb15ba41e6d58cb678d813258"
+mixkey = "a87db88246ec0eedda347b9b643864bee3d6933eb15ba41e6d58cb678d813258"
 rendezvous = true
 listen-address = "127.0.0.1"
 nat = "extip:127.0.0.1"

waku/node/kernel_api/lightpush.nim

@@ -199,7 +199,7 @@ proc lightpushPublishHandler(
     if mixify: #indicates we want to use mix to send the message
       #TODO: How to handle multiple addresses?
       let conn = node.wakuMix.toConnection(
-        MixDestination.init(peer.peerId, peer.addrs[0]),
+        MixDestination.exitNode(peer.peerId),
         WakuLightPushCodec,
         MixParameters(expectReply: Opt.some(true), numSurbs: Opt.some(byte(1))),
           # indicating we only want a single path to be used for reply hence numSurbs = 1

waku/waku_mix/protocol.nim

@@ -21,7 +21,7 @@ import
 logScope:
   topics = "waku mix"
 
-const mixMixPoolSize = 3
+const minMixPoolSize = 4
 
 type
   WakuMix* = ref object of MixProtocol
@@ -181,12 +181,12 @@ proc new*(
     peermgr.switch.peerInfo.peerId, nodeMultiAddr, mixPubKey, mixPrivKey,
     peermgr.switch.peerInfo.publicKey.skkey, peermgr.switch.peerInfo.privateKey.skkey,
   )
-  if bootnodes.len < mixMixPoolSize:
-    warn "publishing with mix won't work until there are 3 mix nodes in node pool"
+  if bootnodes.len < minMixPoolSize:
+    warn "publishing with mix won't work until atleast 3 mix nodes in node pool"
   let initTable = processBootNodes(bootnodes, peermgr)
 
-  if len(initTable) < mixMixPoolSize:
-    warn "publishing with mix won't work until there are 3 mix nodes in node pool"
+  if len(initTable) < minMixPoolSize:
+    warn "publishing with mix won't work until atleast  3 mix nodes in node pool"
   var m = WakuMix(peerManager: peermgr, clusterId: clusterId, pubKey: mixPubKey)
   procCall MixProtocol(m).init(localMixNodeInfo, initTable, peermgr.switch)
   return ok(m)

waku/waku_rendezvous/protocol.nim

@@ -234,4 +234,7 @@ proc stopWait*(self: WakuRendezVous) {.async: (raises: []).} =
   # Stop the parent GenericRendezVous (stops the register deletion loop)
   await GenericRendezVous[WakuPeerRecord](self).stop()
 
+  # Stop the parent GenericRendezVous (stops the register deletion loop)
+  await GenericRendezVous[WakuPeerRecord](self).stop()
+
   info "waku rendezvous discovery stopped"