diff --git a/libp2p/connection.nim b/libp2p/connection.nim
index dd359613b..5395be965 100644
--- a/libp2p/connection.nim
+++ b/libp2p/connection.nim
@@ -141,4 +141,5 @@ method getObservedAddrs*(c: Connection): Future[MultiAddress] {.base, async, gcs
   result = c.observedAddrs
 
 proc `$`*(conn: Connection): string =
-  result = $(conn.peerInfo)
+  if not isNil(conn.peerInfo):
+    result = $(conn.peerInfo)
diff --git a/libp2p/protocols/identify.nim b/libp2p/protocols/identify.nim
index 43e10833d..3bed4e0bf 100644
--- a/libp2p/protocols/identify.nim
+++ b/libp2p/protocols/identify.nim
@@ -139,7 +139,7 @@ proc identify*(p: Identify,
     if peer != remotePeerInfo.peerId:
       trace "Peer ids don't match",
             remote = peer.pretty(),
-            local = remotePeerInfo.get().id
+            local = remotePeerInfo.id
 
       raise newException(IdentityNoMatchError,
         "Peer ids don't match")
diff --git a/libp2p/protocols/pubsub/floodsub.nim b/libp2p/protocols/pubsub/floodsub.nim
index 3abb8d65d..73916e10b 100644
--- a/libp2p/protocols/pubsub/floodsub.nim
+++ b/libp2p/protocols/pubsub/floodsub.nim
@@ -46,26 +46,31 @@ method subscribeTopic*(f: FloodSub,
     # unsubscribe the peer from the topic
     f.floodsub[topic].excl(peerId)
 
-method handleDisconnect*(f: FloodSub, peer: PubSubPeer) {.async, gcsafe.} =
+method handleDisconnect*(f: FloodSub, peer: PubSubPeer) {.async.} =
   ## handle peer disconnects
   for t in f.floodsub.keys:
     f.floodsub[t].excl(peer.id)
 
 method rpcHandler*(f: FloodSub,
                    peer: PubSubPeer,
-                   rpcMsgs: seq[RPCMsg]) {.async, gcsafe.} =
-  trace "processing RPC message", peer = peer.id, msg = rpcMsgs
-  for m in rpcMsgs:                                # for all RPC messages
-    trace "processing message", msg = rpcMsgs
-    if m.subscriptions.len > 0:                    # if there are any subscriptions
-      for s in m.subscriptions:                    # subscribe/unsubscribe the peer for each topic
-        f.subscribeTopic(s.topic, s.subscribe, peer.id)
+                   rpcMsgs: seq[RPCMsg]) {.async.} =
+  await procCall PubSub(f).rpcHandler(peer, rpcMsgs)
 
+  for m in rpcMsgs:                                # for all RPC messages
     if m.messages.len > 0:                           # if there are any messages
       var toSendPeers: HashSet[string] = initHashSet[string]()
       for msg in m.messages:                         # for every message
         if msg.msgId notin f.seen:
           f.seen.put(msg.msgId)                      # add the message to the seen cache
+
+          if not msg.verify(peer.peerInfo):
+            trace "dropping message due to failed signature verification"
+            continue
+
+          if not (await f.validate(msg)):
+            trace "dropping message due to failed validation"
+            continue
+
           for t in msg.topicIDs:                     # for every topic in the message
             if t in f.floodsub:
               toSendPeers.incl(f.floodsub[t])        # get all the peers interested in this topic
@@ -79,7 +84,7 @@ method rpcHandler*(f: FloodSub,
             await f.peers[p].send(@[RPCMsg(messages: m.messages)])
 
 method init(f: FloodSub) =
-  proc handler(conn: Connection, proto: string) {.async, gcsafe.} =
+  proc handler(conn: Connection, proto: string) {.async.} =
     ## main protocol handler that gets triggered on every
     ## connection for a protocol string
     ## e.g. ``/floodsub/1.0.0``, etc...
@@ -92,7 +97,7 @@ method init(f: FloodSub) =
 
 method publish*(f: FloodSub,
                 topic: string,
-                data: seq[byte]) {.async, gcsafe.} =
+                data: seq[byte]) {.async.} =
   await procCall PubSub(f).publish(topic, data)
 
   if data.len <= 0 or topic.len <= 0:
@@ -110,7 +115,7 @@ method publish*(f: FloodSub,
     await f.peers[p].send(@[RPCMsg(messages: @[msg])])
 
 method unsubscribe*(f: FloodSub,
-                    topics: seq[TopicPair]) {.async, gcsafe.} =
+                    topics: seq[TopicPair]) {.async.} =
   await procCall PubSub(f).unsubscribe(topics)
 
   for p in f.peers.values:
diff --git a/libp2p/protocols/pubsub/gossipsub.nim b/libp2p/protocols/pubsub/gossipsub.nim
index 532a3914f..dd64a6d5b 100644
--- a/libp2p/protocols/pubsub/gossipsub.nim
+++ b/libp2p/protocols/pubsub/gossipsub.nim
@@ -73,7 +73,7 @@ proc addInterval(every: Duration, cb: CallbackFunc,
   return retFuture
 
 method init(g: GossipSub) =
-  proc handler(conn: Connection, proto: string) {.async, gcsafe.} =
+  proc handler(conn: Connection, proto: string) {.async.} =
     ## main protocol handler that gets triggered on every
     ## connection for a protocol string
     ## e.g. ``/floodsub/1.0.0``, etc...
@@ -84,7 +84,7 @@ method init(g: GossipSub) =
   g.handler = handler
   g.codec = GossipSubCodec
 
-method handleDisconnect(g: GossipSub, peer: PubSubPeer) {.async, gcsafe.} =
+method handleDisconnect(g: GossipSub, peer: PubSubPeer) {.async.} =
   ## handle peer disconnects
   await procCall FloodSub(g).handleDisconnect(peer)
   for t in g.gossipsub.keys:
@@ -161,16 +161,10 @@ proc handleIWant(g: GossipSub, peer: PubSubPeer, iwants: seq[
 
 method rpcHandler(g: GossipSub,
                   peer: PubSubPeer,
-                  rpcMsgs: seq[RPCMsg]) {.async, gcsafe.} =
+                  rpcMsgs: seq[RPCMsg]) {.async.} =
   await procCall PubSub(g).rpcHandler(peer, rpcMsgs)
 
-  trace "processing RPC message", peer = peer.id, msg = rpcMsgs
-  for m in rpcMsgs:                                # for all RPC messages
-    trace "processing messages", msg = rpcMsgs
-    if m.subscriptions.len > 0:                    # if there are any subscriptions
-      for s in m.subscriptions:                    # subscribe/unsubscribe the peer for each topic
-        g.subscribeTopic(s.topic, s.subscribe, peer.id)
-
+  for m in rpcMsgs:                                  # for all RPC messages
     if m.messages.len > 0:                           # if there are any messages
       var toSendPeers: HashSet[string] = initHashSet[string]()
       for msg in m.messages:                         # for every message
@@ -181,6 +175,14 @@ method rpcHandler(g: GossipSub,
 
         g.seen.put(msg.msgId)                        # add the message to the seen cache
 
+        if not msg.verify(peer.peerInfo):
+          trace "dropping message due to failed signature verification"
+          continue
+
+        if not (await g.validate(msg)):
+          trace "dropping message due to failed validation"
+          continue
+
         # this shouldn't happen
         if g.peerInfo.peerId == msg.fromPeerId():
           trace "skipping messages from self", msg = msg.msgId
@@ -227,10 +229,9 @@ method rpcHandler(g: GossipSub,
 
       if respControl.graft.len > 0 or respControl.prune.len > 0 or
          respControl.ihave.len > 0 or respControl.iwant.len > 0:
-        await peer.send(@[RPCMsg(control: some(respControl),
-            messages: messages)])
+        await peer.send(@[RPCMsg(control: some(respControl), messages: messages)])
 
-proc replenishFanout(g: GossipSub, topic: string) {.async, gcsafe.} =
+proc replenishFanout(g: GossipSub, topic: string) {.async.} =
   ## get fanout peers for a topic
   trace "about to replenish fanout"
   if topic notin g.fanout:
@@ -246,7 +247,7 @@ proc replenishFanout(g: GossipSub, topic: string) {.async, gcsafe.} =
 
   trace "fanout replenished with peers", peers = g.fanout[topic].len
 
-proc rebalanceMesh(g: GossipSub, topic: string) {.async, gcsafe.} =
+proc rebalanceMesh(g: GossipSub, topic: string) {.async.} =
   trace "about to rebalance mesh"
   # create a mesh topic that we're subscribing to
   if topic notin g.mesh:
@@ -288,7 +289,7 @@ proc rebalanceMesh(g: GossipSub, topic: string) {.async, gcsafe.} =
 
   trace "mesh balanced, got peers", peers = g.mesh[topic].len
 
-proc dropFanoutPeers(g: GossipSub) {.async, gcsafe.} =
+proc dropFanoutPeers(g: GossipSub) {.async.} =
   # drop peers that we haven't published to in
   # GossipSubFanoutTTL seconds
   for topic in g.lastFanoutPubSub.keys:
@@ -334,7 +335,7 @@ proc getGossipPeers(g: GossipSub): Table[string, ControlMessage] {.gcsafe.} =
           result[id] = ControlMessage()
         result[id].ihave.add(ihave)
 
-proc heartbeat(g: GossipSub) {.async, gcsafe.} =
+proc heartbeat(g: GossipSub) {.async.} =
   trace "running heartbeat"
 
   await g.heartbeatLock.acquire()
@@ -353,12 +354,12 @@ proc heartbeat(g: GossipSub) {.async, gcsafe.} =
 
 method subscribe*(g: GossipSub,
                   topic: string,
-                  handler: TopicHandler) {.async, gcsafe.} =
+                  handler: TopicHandler) {.async.} =
   await procCall PubSub(g).subscribe(topic, handler)
   asyncCheck g.rebalanceMesh(topic)
 
 method unsubscribe*(g: GossipSub,
-                    topics: seq[TopicPair]) {.async, gcsafe.} =
+                    topics: seq[TopicPair]) {.async.} =
   await procCall PubSub(g).unsubscribe(topics)
 
   for pair in topics:
@@ -372,10 +373,11 @@ method unsubscribe*(g: GossipSub,
 
 method publish*(g: GossipSub,
                 topic: string,
-                data: seq[byte]) {.async, gcsafe.} =
+                data: seq[byte]) {.async.} =
   await procCall PubSub(g).publish(topic, data)
 
-  trace "about to publish message on topic", name = topic, data = data.toHex()
+  trace "about to publish message on topic", name = topic,
+                                             data = data.toHex()
   if data.len > 0 and topic.len > 0:
     var peers: HashSet[string]
     if topic in g.topics: # if we're subscribed to the topic attempt to build a mesh
@@ -453,7 +455,7 @@ when isMainModule and not defined(release):
 
         let topic = "foobar"
         gossipSub.mesh[topic] = initHashSet[string]()
-        proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
+        proc writeHandler(data: seq[byte]) {.async.} =
           discard
 
         for i in 0..<15:
@@ -480,7 +482,7 @@ when isMainModule and not defined(release):
 
         let topic = "foobar"
         gossipSub.gossipsub[topic] = initHashSet[string]()
-        proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
+        proc writeHandler(data: seq[byte]) {.async.} =
           discard
 
         for i in 0..<15:
@@ -505,12 +507,12 @@ when isMainModule and not defined(release):
         let gossipSub = newPubSub(TestGossipSub,
                                   PeerInfo.init(PrivateKey.random(RSA)))
 
-        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async, gcsafe.} =
+        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async.} =
           discard
 
         let topic = "foobar"
         gossipSub.gossipsub[topic] = initHashSet[string]()
-        proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
+        proc writeHandler(data: seq[byte]) {.async.} =
           discard
 
         for i in 0..<15:
@@ -535,13 +537,13 @@ when isMainModule and not defined(release):
         let gossipSub = newPubSub(TestGossipSub,
                                   PeerInfo.init(PrivateKey.random(RSA)))
 
-        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async, gcsafe.} =
+        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async.} =
           discard
 
         let topic = "foobar"
         gossipSub.fanout[topic] = initHashSet[string]()
         gossipSub.lastFanoutPubSub[topic] = Moment.fromNow(100.millis)
-        proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
+        proc writeHandler(data: seq[byte]) {.async.} =
           discard
 
         for i in 0..<6:
@@ -568,7 +570,7 @@ when isMainModule and not defined(release):
         let gossipSub = newPubSub(TestGossipSub,
                                   PeerInfo.init(PrivateKey.random(RSA)))
 
-        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async, gcsafe.} =
+        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async.} =
           discard
 
         let topic1 = "foobar1"
@@ -578,7 +580,7 @@ when isMainModule and not defined(release):
         gossipSub.lastFanoutPubSub[topic1] = Moment.fromNow(100.millis)
         gossipSub.lastFanoutPubSub[topic1] = Moment.fromNow(500.millis)
 
-        proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
+        proc writeHandler(data: seq[byte]) {.async.} =
           discard
 
         for i in 0..<6:
@@ -608,10 +610,10 @@ when isMainModule and not defined(release):
         let gossipSub = newPubSub(TestGossipSub,
                                   PeerInfo.init(PrivateKey.random(RSA)))
 
-        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async, gcsafe.} =
+        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async.} =
           discard
 
-        proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
+        proc writeHandler(data: seq[byte]) {.async.} =
           discard
 
         let topic = "foobar"
@@ -657,10 +659,10 @@ when isMainModule and not defined(release):
         let gossipSub = newPubSub(TestGossipSub,
                                   PeerInfo.init(PrivateKey.random(RSA)))
 
-        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async, gcsafe.} =
+        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async.} =
           discard
 
-        proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
+        proc writeHandler(data: seq[byte]) {.async.} =
           discard
 
         let topic = "foobar"
@@ -689,10 +691,10 @@ when isMainModule and not defined(release):
         let gossipSub = newPubSub(TestGossipSub,
                                   PeerInfo.init(PrivateKey.random(RSA)))
 
-        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async, gcsafe.} =
+        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async.} =
           discard
 
-        proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
+        proc writeHandler(data: seq[byte]) {.async.} =
           discard
 
         let topic = "foobar"
@@ -721,10 +723,10 @@ when isMainModule and not defined(release):
         let gossipSub = newPubSub(TestGossipSub,
                                   PeerInfo.init(PrivateKey.random(RSA)))
 
-        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async, gcsafe.} =
+        proc handler(peer: PubSubPeer, msg: seq[RPCMsg]) {.async.} =
           discard
 
-        proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
+        proc writeHandler(data: seq[byte]) {.async.} =
           discard
 
         let topic = "foobar"
diff --git a/libp2p/protocols/pubsub/pubsub.nim b/libp2p/protocols/pubsub/pubsub.nim
index c591dff79..e9250795c 100644
--- a/libp2p/protocols/pubsub/pubsub.nim
+++ b/libp2p/protocols/pubsub/pubsub.nim
@@ -7,7 +7,7 @@
 ## This file may not be copied, modified, or distributed except according to
 ## those terms.
 
-import tables, options, sequtils
+import tables, sequtils, sets
 import chronos, chronicles
 import pubsubpeer,
        rpc/messages,
@@ -22,8 +22,11 @@ logScope:
   topic = "PubSub"
 
 type
-  TopicHandler* = proc (topic: string,
-                        data: seq[byte]): Future[void] {.gcsafe.}
+  TopicHandler* = proc(topic: string,
+                       data: seq[byte]): Future[void] {.gcsafe.}
+
+  ValidatorHandler* = proc(topic: string,
+                           message: Message): Future[bool] {.closure.}
 
   TopicPair* = tuple[topic: string, handler: TopicHandler]
 
@@ -37,11 +40,12 @@ type
     peers*: Table[string, PubSubPeer] # peerid to peer map
     triggerSelf*: bool                # trigger own local handler on publish
     cleanupLock: AsyncLock
+    validators*: Table[string, HashSet[ValidatorHandler]]
 
 proc sendSubs*(p: PubSub,
                peer: PubSubPeer,
                topics: seq[string],
-               subscribe: bool) {.async, gcsafe.} =
+               subscribe: bool) {.async.} =
   ## send subscriptions to remote peer
   trace "sending subscriptions", peer = peer.id,
                                  subscribe = subscribe,
@@ -56,13 +60,24 @@ proc sendSubs*(p: PubSub,
 
   await peer.send(@[msg])
 
-method rpcHandler*(p: PubSub,
-                   peer: PubSubPeer,
-                   rpcMsgs: seq[RPCMsg]) {.async, base, gcsafe.} =
-  ## handle rpc messages
+method subscribeTopic*(p: PubSub,
+                       topic: string,
+                       subscribe: bool,
+                       peerId: string) {.base.} =
   discard
 
-method handleDisconnect*(p: PubSub, peer: PubSubPeer) {.async, base, gcsafe.} =
+method rpcHandler*(p: PubSub,
+                   peer: PubSubPeer,
+                   rpcMsgs: seq[RPCMsg]) {.async, base.} =
+  ## handle rpc messages
+  trace "processing RPC message", peer = peer.id, msg = rpcMsgs
+  for m in rpcMsgs:                                # for all RPC messages
+    trace "processing messages", msg = rpcMsgs
+    if m.subscriptions.len > 0:                    # if there are any subscriptions
+      for s in m.subscriptions:                    # subscribe/unsubscribe the peer for each topic
+        p.subscribeTopic(s.topic, s.subscribe, peer.id)
+
+method handleDisconnect*(p: PubSub, peer: PubSubPeer) {.async, base.} =
   ## handle peer disconnects
   if peer.id in p.peers:
     p.peers.del(peer.id)
@@ -90,7 +105,7 @@ proc getPeer(p: PubSub, peerInfo: PeerInfo, proto: string): PubSubPeer =
 
 method handleConn*(p: PubSub,
                    conn: Connection,
-                   proto: string) {.base, async, gcsafe.} =
+                   proto: string) {.base, async.} =
   ## handle incoming connections
   ##
   ## this proc will:
@@ -107,7 +122,7 @@ method handleConn*(p: PubSub,
     await conn.close()
     return
 
-  proc handler(peer: PubSubPeer, msgs: seq[RPCMsg]) {.async, gcsafe.} =
+  proc handler(peer: PubSubPeer, msgs: seq[RPCMsg]) {.async.} =
     # call floodsub rpc handler
     await p.rpcHandler(peer, msgs)
 
@@ -122,7 +137,7 @@ method handleConn*(p: PubSub,
   await p.cleanUpHelper(peer)
 
 method subscribeToPeer*(p: PubSub,
-                        conn: Connection) {.base, async, gcsafe.} =
+                        conn: Connection) {.base, async.} =
   var peer = p.getPeer(conn.peerInfo, p.codec)
   trace "setting connection for peer", peerId = conn.peerInfo.id
   if not peer.isConnected:
@@ -137,7 +152,7 @@ method subscribeToPeer*(p: PubSub,
     asyncCheck p.cleanUpHelper(peer)
 
 method unsubscribe*(p: PubSub,
-                    topics: seq[TopicPair]) {.base, async, gcsafe.} =
+                    topics: seq[TopicPair]) {.base, async.} =
   ## unsubscribe from a list of ``topic`` strings
   for t in topics:
     for i, h in p.topics[t.topic].handler:
@@ -146,19 +161,13 @@ method unsubscribe*(p: PubSub,
 
 method unsubscribe*(p: PubSub,
                     topic: string,
-                    handler: TopicHandler): Future[void] {.base, gcsafe.} =
+                    handler: TopicHandler): Future[void] {.base.} =
   ## unsubscribe from a ``topic`` string
   result = p.unsubscribe(@[(topic, handler)])
 
-method subscribeTopic*(p: PubSub,
-                       topic: string,
-                       subscribe: bool,
-                       peerId: string) {.base, gcsafe.} =
-  discard
-
 method subscribe*(p: PubSub,
                   topic: string,
-                  handler: TopicHandler) {.base, async, gcsafe.} =
+                  handler: TopicHandler) {.base, async.} =
   ## subscribe to a topic
   ##
   ## ``topic``   - a string topic to subscribe to
@@ -178,7 +187,7 @@ method subscribe*(p: PubSub,
 
 method publish*(p: PubSub,
                 topic: string,
-                data: seq[byte]) {.base, async, gcsafe.} =
+                data: seq[byte]) {.base, async.} =
   ## publish to a ``topic``
   if p.triggerSelf and topic in p.topics:
     for h in p.topics[topic].handler:
@@ -190,14 +199,44 @@ method initPubSub*(p: PubSub) {.base.} =
 
 method start*(p: PubSub) {.async, base.} =
   ## start pubsub
-  ## start long running/repeating procedures
   discard
 
 method stop*(p: PubSub) {.async, base.} =
   ## stopt pubsub
-  ## stop long running/repeating procedures
   discard
 
+method addValidator*(p: PubSub,
+                     topic: varargs[string],
+                     hook: ValidatorHandler) {.base.} =
+  for t in topic:
+    if t notin p.validators:
+      p.validators[t] = initHashSet[ValidatorHandler]()
+
+    trace "adding validator for topic", topicId = t
+    p.validators[t].incl(hook)
+
+method removeValidator*(p: PubSub,
+                        topic: varargs[string],
+                        hook: ValidatorHandler) {.base.} =
+  for t in topic:
+    if t in p.validators:
+      p.validators[t].excl(hook)
+
+method validate*(p: PubSub, message: Message): Future[bool] {.async, base.} =
+  var pending: seq[Future[bool]]
+  trace "about to validate message"
+  for topic in message.topicIDs:
+    trace "looking for validators on topic", topicID = topic,
+                                             registered = toSeq(p.validators.keys)
+    if topic in p.validators:
+      trace "running validators for topic", topicID = topic
+      # TODO: add timeout to validator
+      pending.add(p.validators[topic].mapIt(it(topic, message)))
+
+  await allFutures(pending) # await all futures
+  if pending.allIt(it.read()): # if there are failed
+    result = true
+
 proc newPubSub*(p: typedesc[PubSub],
                 peerInfo: PeerInfo,
                 triggerSelf: bool = false): p =
diff --git a/libp2p/protocols/pubsub/pubsubpeer.nim b/libp2p/protocols/pubsub/pubsubpeer.nim
index 1a5c440a6..eb8c091d4 100644
--- a/libp2p/protocols/pubsub/pubsubpeer.nim
+++ b/libp2p/protocols/pubsub/pubsubpeer.nim
@@ -45,7 +45,7 @@ proc `conn=`*(p: PubSubPeer, conn: Connection) =
   p.sendConn = conn
   p.onConnect.fire()
 
-proc handle*(p: PubSubPeer, conn: Connection) {.async, gcsafe.} =
+proc handle*(p: PubSubPeer, conn: Connection) {.async.} =
   trace "handling pubsub rpc", peer = p.id, closed = conn.closed
   try:
     while not conn.closed:
@@ -66,7 +66,7 @@ proc handle*(p: PubSubPeer, conn: Connection) {.async, gcsafe.} =
   finally:
     trace "exiting pubsub peer read loop", peer = p.id
 
-proc send*(p: PubSubPeer, msgs: seq[RPCMsg]) {.async, gcsafe.} =
+proc send*(p: PubSubPeer, msgs: seq[RPCMsg]) {.async.} =
   try:
     for m in msgs:
       trace "sending msgs to peer", toPeer = p.id
@@ -105,12 +105,12 @@ proc sendMsg*(p: PubSubPeer,
               data: seq[byte]): Future[void] {.gcsafe.} =
   p.send(@[RPCMsg(messages: @[newMessage(p.peerInfo, data, topic)])])
 
-proc sendGraft*(p: PubSubPeer, topics: seq[string]) {.async, gcsafe.} =
+proc sendGraft*(p: PubSubPeer, topics: seq[string]) {.async.} =
   for topic in topics:
     trace "sending graft msg to peer", peer = p.id, topicID = topic
     await p.send(@[RPCMsg(control: some(ControlMessage(graft: @[ControlGraft(topicID: topic)])))])
 
-proc sendPrune*(p: PubSubPeer, topics: seq[string]) {.async, gcsafe.} =
+proc sendPrune*(p: PubSubPeer, topics: seq[string]) {.async.} =
   for topic in topics:
     trace "sending prune msg to peer", peer = p.id, topicID = topic
     await p.send(@[RPCMsg(control: some(ControlMessage(prune: @[ControlPrune(topicID: topic)])))])
diff --git a/libp2p/protocols/pubsub/rpc/message.nim b/libp2p/protocols/pubsub/rpc/message.nim
index 9bceb9a49..66339504c 100644
--- a/libp2p/protocols/pubsub/rpc/message.nim
+++ b/libp2p/protocols/pubsub/rpc/message.nim
@@ -27,17 +27,16 @@ proc msgId*(m: Message): string =
 proc fromPeerId*(m: Message): PeerId =
   PeerID.init(m.fromPeer)
 
-proc sign*(p: PeerInfo, msg: Message): Message {.gcsafe.} =
+proc sign*(msg: Message, p: PeerInfo): Message {.gcsafe.} =
   var buff = initProtoBuffer()
   encodeMessage(msg, buff)
-  let prefix = cast[seq[byte]](PubSubPrefix)
   if buff.buffer.len > 0:
     result = msg
     result.signature = p.privateKey.
-                       sign(prefix & buff.buffer).
+                       sign(cast[seq[byte]](PubSubPrefix) & buff.buffer).
                        getBytes()
 
-proc verify*(p: PeerInfo, m: Message): bool =
+proc verify*(m: Message, p: PeerInfo): bool =
   if m.signature.len > 0 and m.key.len > 0:
     var msg = m
     msg.signature = @[]
@@ -49,7 +48,8 @@ proc verify*(p: PeerInfo, m: Message): bool =
     var remote: Signature
     var key: PublicKey
     if remote.init(m.signature) and key.init(m.key):
-      result = remote.verify(buff.buffer, key)
+      trace "verifying signature", remoteSignature = remote
+      result = remote.verify(cast[seq[byte]](PubSubPrefix) & buff.buffer, key)
 
 proc newMessage*(p: PeerInfo,
                  data: seq[byte],
@@ -64,6 +64,6 @@ proc newMessage*(p: PeerInfo,
                      seqno: seqno,
                      topicIDs: @[name])
     if sign:
-      result = p.sign(result)
+      result = result.sign(p)
 
     result.key = key
diff --git a/libp2p/protocols/secure/secio.nim b/libp2p/protocols/secure/secio.nim
index a1f0a332f..55ea08924 100644
--- a/libp2p/protocols/secure/secio.nim
+++ b/libp2p/protocols/secure/secio.nim
@@ -437,16 +437,15 @@ proc handleConn(s: Secio, conn: Connection): Future[Connection] {.async, gcsafe.
 
   var stream = newBufferStream(writeHandler)
   asyncCheck readLoop(sconn, stream)
-  var secured = newConnection(stream)
-  secured.peerInfo = PeerInfo.init(sconn.peerInfo.publicKey.get())
-  result = secured
-
-  secured.closeEvent.wait()
+  result = newConnection(stream)
+  result.closeEvent.wait()
     .addCallback do (udata: pointer):
         trace "wrapped connection closed, closing upstream"
         if not isNil(sconn) and not sconn.closed:
           asyncCheck sconn.close()
 
+  result.peerInfo = PeerInfo.init(sconn.peerInfo.publicKey.get())
+
 method init(s: Secio) {.gcsafe.} =
   proc handle(conn: Connection, proto: string) {.async, gcsafe.} =
     trace "handling connection"
diff --git a/libp2p/switch.nim b/libp2p/switch.nim
index 358d067c6..995b7fbb3 100644
--- a/libp2p/switch.nim
+++ b/libp2p/switch.nim
@@ -314,6 +314,24 @@ proc publish*(s: Switch, topic: string, data: seq[byte]): Future[void] {.gcsafe.
 
   result = s.pubSub.get().publish(topic, data)
 
+proc addValidator*(s: Switch,
+                   topics: varargs[string],
+                   hook: ValidatorHandler) =
+  # add validator
+  if s.pubSub.isNone:
+    raise newNoPubSubException()
+
+  s.pubSub.get().addValidator(topics, hook)
+
+proc removeValidator*(s: Switch,
+                      topics: varargs[string],
+                      hook: ValidatorHandler) =
+  # pubslish to pubsub topic
+  if s.pubSub.isNone:
+    raise newNoPubSubException()
+
+  s.pubSub.get().removeValidator(topics, hook)
+
 proc newSwitch*(peerInfo: PeerInfo,
                 transports: seq[Transport],
                 identity: Identify,
diff --git a/tests/pubsub/testfloodsub.nim b/tests/pubsub/testfloodsub.nim
index 937fc1fff..b6b603d1c 100644
--- a/tests/pubsub/testfloodsub.nim
+++ b/tests/pubsub/testfloodsub.nim
@@ -10,11 +10,15 @@
 import unittest, sequtils, options
 import chronos
 import utils,
-       ../../libp2p/[switch, crypto/crypto]
+       ../../libp2p/[switch,
+                     crypto/crypto,
+                     protocols/pubsub/pubsub,
+                     protocols/pubsub/rpc/messages,
+                     protocols/pubsub/rpc/message]
 
 suite "FloodSub":
   test "FloodSub basic publish/subscribe A -> B":
-    proc testBasicPubSub(): Future[bool] {.async.} =
+    proc runTests(): Future[bool] {.async.} =
       var completionFut = newFuture[bool]()
       proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
         check topic == "foobar"
@@ -36,10 +40,10 @@ suite "FloodSub":
       await allFutures(awaiters)
 
     check:
-      waitFor(testBasicPubSub()) == true
+      waitFor(runTests()) == true
 
   test "FloodSub basic publish/subscribe B -> A":
-    proc testBasicPubSub(): Future[bool] {.async.} =
+    proc runTests(): Future[bool] {.async.} =
       var completionFut = newFuture[bool]()
       proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
         check topic == "foobar"
@@ -61,10 +65,107 @@ suite "FloodSub":
       await allFutures(awaiters)
 
     check:
-      waitFor(testBasicPubSub()) == true
+      waitFor(runTests()) == true
+
+  test "FloodSub validation should succeed":
+    proc runTests(): Future[bool] {.async.} =
+      var handlerFut = newFuture[bool]()
+      proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
+        check topic == "foobar"
+        handlerFut.complete(true)
+
+      var nodes = generateNodes(2)
+      var awaiters: seq[Future[void]]
+      awaiters.add((await nodes[0].start()))
+      awaiters.add((await nodes[1].start()))
+
+      await subscribeNodes(nodes)
+      await nodes[1].subscribe("foobar", handler)
+      await sleepAsync(1000.millis)
+
+      var validatorFut = newFuture[bool]()
+      proc validator(topic: string,
+                     message: Message): Future[bool] {.async.} =
+        check topic == "foobar"
+        validatorFut.complete(true)
+        result = true
+
+      nodes[1].addValidator("foobar", validator)
+      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+
+      await allFutures(handlerFut, handlerFut)
+      await allFutures(nodes[0].stop(), nodes[1].stop())
+      await allFutures(awaiters)
+      result = true
+    check:
+      waitFor(runTests()) == true
+
+  test "FloodSub validation should fail":
+    proc runTests(): Future[bool] {.async.} =
+      proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
+        check false # if we get here, it should fail
+
+      var nodes = generateNodes(2)
+      var awaiters: seq[Future[void]]
+      awaiters.add((await nodes[0].start()))
+      awaiters.add((await nodes[1].start()))
+
+      await subscribeNodes(nodes)
+      await nodes[1].subscribe("foobar", handler)
+      await sleepAsync(100.millis)
+
+      var validatorFut = newFuture[bool]()
+      proc validator(topic: string,
+                     message: Message): Future[bool] {.async.} =
+        validatorFut.complete(true)
+        result = false
+
+      nodes[1].addValidator("foobar", validator)
+      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+      await allFutures(nodes[0].stop(), nodes[1].stop())
+      await allFutures(awaiters)
+      result = true
+
+    check:
+      waitFor(runTests()) == true
+
+  test "FloodSub validation one fails and one succeeds":
+    proc runTests(): Future[bool] {.async.} =
+      var handlerFut = newFuture[bool]()
+      proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
+        check topic == "foo"
+        handlerFut.complete(true)
+
+      var nodes = generateNodes(2)
+      var awaiters: seq[Future[void]]
+      awaiters.add((await nodes[0].start()))
+      awaiters.add((await nodes[1].start()))
+
+      await subscribeNodes(nodes)
+      await nodes[1].subscribe("foo", handler)
+      await nodes[1].subscribe("bar", handler)
+      await sleepAsync(1000.millis)
+
+      proc validator(topic: string,
+                     message: Message): Future[bool] {.async.} =
+        if topic == "foo":
+          result = true
+        else:
+          result = false
+
+      nodes[1].addValidator("foo", "bar", validator)
+      await nodes[0].publish("foo", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("bar", cast[seq[byte]]("Hello!"))
+
+      await sleepAsync(100.millis)
+      await allFutures(nodes[0].stop(), nodes[1].stop())
+      await allFutures(awaiters)
+      result = true
+    check:
+      waitFor(runTests()) == true
 
   test "FloodSub multiple peers, no self trigger":
-    proc testBasicFloodSub(): Future[bool] {.async.} =
+    proc runTests(): Future[bool] {.async.} =
       var passed: int
       proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
         check topic == "foobar"
@@ -93,10 +194,10 @@ suite "FloodSub":
       result = passed >= 10 # non deterministic, so at least 2 times
 
     check:
-      waitFor(testBasicFloodSub()) == true
+      waitFor(runTests()) == true
 
   test "FloodSub multiple peers, with self trigger":
-    proc testBasicFloodSub(): Future[bool] {.async.} =
+    proc runTests(): Future[bool] {.async.} =
       var passed: int
       proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
         check topic == "foobar"
@@ -127,4 +228,4 @@ suite "FloodSub":
       result = passed >= 10 # non deterministic, so at least 20 times
 
     check:
-      waitFor(testBasicFloodSub()) == true
+      waitFor(runTests()) == true
diff --git a/tests/pubsub/testgossipsub.nim b/tests/pubsub/testgossipsub.nim
index e8be14ee2..958b68d05 100644
--- a/tests/pubsub/testgossipsub.nim
+++ b/tests/pubsub/testgossipsub.nim
@@ -9,22 +9,126 @@
 
 import unittest, sequtils, options, tables, sets
 import chronos
-import utils, ../../libp2p/[switch,
-                            peer,
+import utils, ../../libp2p/[peer,
                             peerinfo,
                             connection,
                             crypto/crypto,
                             stream/bufferstream,
                             protocols/pubsub/pubsub,
-                            protocols/pubsub/gossipsub]
+                            protocols/pubsub/gossipsub,
+                            protocols/pubsub/rpc/messages]
+
 
 proc createGossipSub(): GossipSub =
   var peerInfo = PeerInfo.init(PrivateKey.random(RSA))
   result = newPubSub(GossipSub, peerInfo)
 
 suite "GossipSub":
+  test "GossipSub validation should succeed":
+    proc runTests(): Future[bool] {.async.} =
+      var handlerFut = newFuture[bool]()
+      proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
+        check topic == "foobar"
+        handlerFut.complete(true)
+
+      var nodes = generateNodes(2, true)
+      var awaiters: seq[Future[void]]
+      awaiters.add((await nodes[0].start()))
+      awaiters.add((await nodes[1].start()))
+
+      await subscribeNodes(nodes)
+      await nodes[1].subscribe("foobar", handler)
+      await sleepAsync(1000.millis)
+
+      var validatorFut = newFuture[bool]()
+      proc validator(topic: string,
+                     message: Message):
+                     Future[bool] {.async.} =
+        check topic == "foobar"
+        validatorFut.complete(true)
+        result = true
+
+      nodes[1].addValidator("foobar", validator)
+      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+
+      await allFutures(handlerFut, handlerFut)
+      await allFutures(nodes[0].stop(), nodes[1].stop())
+      await allFutures(awaiters)
+      result = true
+    check:
+      waitFor(runTests()) == true
+
+  test "GossipSub validation should fail":
+    proc runTests(): Future[bool] {.async.} =
+      proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
+        check false # if we get here, it should fail
+
+      var nodes = generateNodes(2, true)
+      var awaiters: seq[Future[void]]
+      awaiters.add((await nodes[0].start()))
+      awaiters.add((await nodes[1].start()))
+
+      await subscribeNodes(nodes)
+      await nodes[1].subscribe("foobar", handler)
+      await sleepAsync(100.millis)
+
+      var validatorFut = newFuture[bool]()
+      proc validator(topic: string,
+                     message: Message):
+                     Future[bool] {.async.} =
+        validatorFut.complete(true)
+        result = false
+
+      nodes[1].addValidator("foobar", validator)
+      await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
+
+      await sleepAsync(100.millis)
+      discard await validatorFut
+      await allFutures(nodes[0].stop(), nodes[1].stop())
+      await allFutures(awaiters)
+      result = true
+
+    check:
+      waitFor(runTests()) == true
+
+  test "GossipSub validation one fails and one succeeds":
+    proc runTests(): Future[bool] {.async.} =
+      var handlerFut = newFuture[bool]()
+      proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
+        check topic == "foo"
+        handlerFut.complete(true)
+
+      var nodes = generateNodes(2, true)
+      var awaiters: seq[Future[void]]
+      awaiters.add((await nodes[0].start()))
+      awaiters.add((await nodes[1].start()))
+
+      await subscribeNodes(nodes)
+      await nodes[1].subscribe("foo", handler)
+      await nodes[1].subscribe("bar", handler)
+      await sleepAsync(1000.millis)
+
+      proc validator(topic: string,
+                     message: Message):
+                     Future[bool] {.async.} =
+        if topic == "foo":
+          result = true
+        else:
+          result = false
+
+      nodes[1].addValidator("foo", "bar", validator)
+      await nodes[0].publish("foo", cast[seq[byte]]("Hello!"))
+      await nodes[0].publish("bar", cast[seq[byte]]("Hello!"))
+
+      await sleepAsync(100.millis)
+      await allFutures(nodes[0].stop(), nodes[1].stop())
+      await allFutures(awaiters)
+      result = true
+    check:
+      waitFor(runTests()) == true
+
   test "should add remote peer topic subscriptions":
-    proc testRun(): Future[bool] {.async.} =
+    proc runTests(): Future[bool] {.async.} =
       proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
         discard
 
@@ -54,7 +158,7 @@ suite "GossipSub":
       result = true
 
     check:
-      waitFor(testRun()) == true
+      waitFor(runTests()) == true
 
   test "e2e - should add remote peer topic subscriptions":
     proc testBasicGossipSub(): Future[bool] {.async.} =
@@ -91,7 +195,7 @@ suite "GossipSub":
       waitFor(testBasicGossipSub()) == true
 
   test "should add remote peer topic subscriptions if both peers are subscribed":
-    proc testRun(): Future[bool] {.async.} =
+    proc runTests(): Future[bool] {.async.} =
       proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
         discard
 
@@ -134,7 +238,7 @@ suite "GossipSub":
       result = true
 
     check:
-      waitFor(testRun()) == true
+      waitFor(runTests()) == true
 
   test "e2e - should add remote peer topic subscriptions if both peers are subscribed":
     proc testBasicGossipSub(): Future[bool] {.async.} =
@@ -179,7 +283,7 @@ suite "GossipSub":
       waitFor(testBasicGossipSub()) == true
 
   # test "send over fanout A -> B":
-  #   proc testRun(): Future[bool] {.async.} =
+  #   proc runTests(): Future[bool] {.async.} =
   #     var handlerFut = newFuture[bool]()
   #     proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
   #       check:
@@ -216,10 +320,10 @@ suite "GossipSub":
   #     result = await handlerFut
 
   #   check:
-  #     waitFor(testRun()) == true
+  #     waitFor(runTests()) == true
 
   test "e2e - send over fanout A -> B":
-    proc testRun(): Future[bool] {.async.} =
+    proc runTests(): Future[bool] {.async.} =
       var passed: bool
       proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
         check topic == "foobar"
@@ -250,10 +354,10 @@ suite "GossipSub":
       result = passed
 
     check:
-      waitFor(testRun()) == true
+      waitFor(runTests()) == true
 
   # test "send over mesh A -> B":
-  #   proc testRun(): Future[bool] {.async.} =
+  #   proc runTests(): Future[bool] {.async.} =
   #     var passed: bool
   #     proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
   #       check:
@@ -289,10 +393,10 @@ suite "GossipSub":
   #     result = passed
 
   #   check:
-  #     waitFor(testRun()) == true
+  #     waitFor(runTests()) == true
 
   # test "e2e - send over mesh A -> B":
-  #   proc testRun(): Future[bool] {.async.} =
+  #   proc runTests(): Future[bool] {.async.} =
   #     var passed: bool
   #     proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
   #       check topic == "foobar"
@@ -318,10 +422,10 @@ suite "GossipSub":
   #     result = passed
 
   #   check:
-  #     waitFor(testRun()) == true
+  #     waitFor(runTests()) == true
 
   # test "with multiple peers":
-  #   proc testRun(): Future[bool] {.async.} =
+  #   proc runTests(): Future[bool] {.async.} =
   #     var nodes: seq[GossipSub]
   #     for i in 0..<10:
   #       nodes.add(createGossipSub())
@@ -376,10 +480,10 @@ suite "GossipSub":
   #     result = true
 
   #   check:
-  #     waitFor(testRun()) == true
+  #     waitFor(runTests()) == true
 
   test "e2e - with multiple peers":
-    proc testRun(): Future[bool] {.async.} =
+    proc runTests(): Future[bool] {.async.} =
       var nodes: seq[Switch] = newSeq[Switch]()
       var awaitters: seq[Future[void]]
 
@@ -419,4 +523,4 @@ suite "GossipSub":
       result = true
 
     check:
-      waitFor(testRun()) == true
+      waitFor(runTests()) == true