Basic proof gen and vrfy (#421)

* adds the proof field to the WakuMessage

* adds a basic zkProof api

* adds proof gen to the publish proc

* relocates the proofGen and proofVrfy to rln_relay_utils

* wip: test of proof gen

* adds a procedure to pass rln-relay message validator, adds the proof gen

* tests the proof gen and verify

* relocates zkp API

* adds documentation and todos

* adds todos and documentations

* removes an unnecessary comment

* adds todos

tests/v2/test_wakunode.nim

@@ -394,4 +394,58 @@ procSuite "WakuNode":
     await node1.stop()
     await node2.stop()
     await node3.stop()
+asyncTest "testing rln-relay with mocked zkp":
+    
+    let
+      # publisher node
+      nodeKey1 = crypto.PrivateKey.random(Secp256k1, rng[])[]
+      node1 = WakuNode.init(nodeKey1, ValidIpAddress.init("0.0.0.0"), Port(60000))
+      # Relay node
+      nodeKey2 = crypto.PrivateKey.random(Secp256k1, rng[])[]
+      node2 = WakuNode.init(nodeKey2, ValidIpAddress.init("0.0.0.0"), Port(60002))
+      # Subscriber
+      nodeKey3 = crypto.PrivateKey.random(Secp256k1, rng[])[]
+      node3 = WakuNode.init(nodeKey3, ValidIpAddress.init("0.0.0.0"), Port(60003))
 
+      pubSubTopic = "defaultTopic"
+      contentTopic1 = ContentTopic(1)
+      payload = "hello world".toBytes()
+      message1 = WakuMessage(payload: payload, contentTopic: contentTopic1)
+
+    # start all the nodes
+    await node1.start()
+    node1.mountRelay(@[pubSubTopic])
+
+    await node2.start()
+    node2.mountRelay(@[pubSubTopic])
+    node2.addRLNRelayValidator(pubSubTopic)
+
+    await node3.start()
+    node3.mountRelay(@[pubSubTopic])
+
+    await node1.connectToNodes(@[node2.peerInfo])
+    await node3.connectToNodes(@[node2.peerInfo])
+
+    var completionFut = newFuture[bool]()
+    proc relayHandler(topic: string, data: seq[byte]) {.async, gcsafe.} =
+      let msg = WakuMessage.init(data)
+      if msg.isOk():
+        let val = msg.value()
+        debug "The received topic:", topic
+        if topic == pubSubTopic:
+          completionFut.complete(true)
+
+
+    node3.subscribe(pubSubTopic, relayHandler)
+    await sleepAsync(2000.millis)
+
+    await node1.publish(pubSubTopic, message1, rlnRelayEnabled = true)
+    await sleepAsync(2000.millis)
+
+
+    check:
+      (await completionFut.withTimeout(10.seconds)) == true
+    
+    await node1.stop()
+    await node2.stop()
+    await node3.stop()

waku/v2/node/wakunode2.nim

@@ -8,9 +8,10 @@ import
   libp2p/crypto/crypto,
   libp2p/protocols/protocol,
   # NOTE For TopicHandler, solve with exports?
+  libp2p/protocols/pubsub/rpc/messages,
   libp2p/protocols/pubsub/pubsub,
   libp2p/standard_setup,
-  ../protocol/[waku_relay, message_notifier],
+  ../protocol/[waku_relay, waku_message, message_notifier],
   ../protocol/waku_store/waku_store,
   ../protocol/waku_swap/waku_swap,
   ../protocol/waku_filter/waku_filter,
@@ -239,17 +240,26 @@ proc unsubscribe*(node: WakuNode, request: FilterRequest) {.async, gcsafe.} =
   waku_node_filters.set(node.filters.len.int64)
 
 
-proc publish*(node: WakuNode, topic: Topic, message: WakuMessage) {.async, gcsafe.} =
+proc publish*(node: WakuNode, topic: Topic, message: WakuMessage,  rlnRelayEnabled: bool = false) {.async, gcsafe.} =
   ## Publish a `WakuMessage` to a PubSub topic. `WakuMessage` should contain a
   ## `contentTopic` field for light node functionality. This field may be also
   ## be omitted.
   ##
   ## Status: Implemented.
-  ##
+  ## When rlnRelayEnabled is true, a zkp will be generated and attached to the message (it is an experimental feature)
 
   let wakuRelay = node.wakuRelay
-
   debug "publish", topic=topic, contentTopic=message.contentTopic
+  var publishingMessage = message
+
+  if rlnRelayEnabled:
+    # if rln relay is enabled then a proof must be generated and added to the waku message
+    let 
+      proof = proofGen(message.payload)
+      ## TODO here  since the message is immutable we have to make a copy of it and then attach the proof to its duplicate 
+      ## TODO however, it might be better to change message type to mutable (i.e., var) so that we can add the proof field to the original message
+      publishingMessage = WakuMessage(payload: message.payload, contentTopic: message.contentTopic, version: message.version, proof: proof)
+
   let data = message.encode().buffer
 
   discard await wakuRelay.publish(topic, data)
@@ -343,6 +353,20 @@ proc mountRlnRelay*(node: WakuNode, ethClientAddress: Option[string] = none(stri
   node.wakuRlnRelay = rlnPeer
 
 
+proc addRLNRelayValidator*(node: WakuNode, pubsubTopic: string) =
+  ## this procedure is a thin wrapper for the pubsub addValidator method
+  ## it sets message validator on the given pubsubTopic, the validator will check that
+  ## all the messages published in the pubsubTopic have a valid zero-knowledge proof 
+  proc validator(topic: string, message: messages.Message): Future[ValidationResult] {.async.} =
+    let msg = WakuMessage.init(message.data) 
+    if msg.isOk():
+      #  check the proof
+      if proofVrfy(msg.value().payload, msg.value().proof):
+        result = ValidationResult.Accept
+  # set a validator for the pubsubTopic 
+  let pb  = PubSub(node.wakuRelay)
+  pb.addValidator(pubsubTopic, validator)
+
 proc mountRelay*(node: WakuNode, topics: seq[string] = newSeq[string](), rlnRelayEnabled = false) {.gcsafe.} =
   let wakuRelay = WakuRelay.init(
     switch = node.switch,
@@ -376,8 +400,11 @@ proc mountRelay*(node: WakuNode, topics: seq[string] = newSeq[string](), rlnRela
     # TODO pass rln relay inputs to this proc, right now it uses default values that are set in the mountRlnRelay proc
     info "WakuRLNRelay is enabled"
     waitFor mountRlnRelay(node)
+    # TODO currently the message validator is set for the defaultTopic, this can be configurable to accept other pubsub topics as well 
+    addRLNRelayValidator(node, defaultTopic)
     info "WakuRLNRelay is mounted successfully"
 
+
 ## Helpers
 proc dialPeer*(n: WakuNode, address: string) {.async.} =
   info "dialPeer", address = address

waku/v2/protocol/waku_message.nim

@@ -16,6 +16,9 @@ type
     payload*: seq[byte]
     contentTopic*: ContentTopic
     version*: uint32
+    # the proof field indicates that the message is not a spam
+    # this field will be used in the rln-relay protocol
+    proof*: seq[byte]
 
 # Encoding and decoding -------------------------------------------------------
 proc init*(T: type WakuMessage, buffer: seq[byte]): ProtoResult[T] =
@@ -25,6 +28,7 @@ proc init*(T: type WakuMessage, buffer: seq[byte]): ProtoResult[T] =
   discard ? pb.getField(1, msg.payload)
   discard ? pb.getField(2, msg.contentTopic)
   discard ? pb.getField(3, msg.version)
+  discard ? pb.getField(4, msg.proof)
 
   ok(msg)
 
@@ -34,3 +38,4 @@ proc encode*(message: WakuMessage): ProtoBuffer =
   result.write(1, message.payload)
   result.write(2, message.contentTopic)
   result.write(3, message.version)
+  result.write(4, message.proof)

waku/v2/protocol/waku_rln_relay/rln.nim

@@ -66,4 +66,6 @@ proc hash*(ctx: ptr RLNBn256, inputs_buffer:ptr Buffer, input_len: ptr csize_t,
 #     output_buffer: *mut Buffer,
 # ) -> bool
 
-{.pop.}
+{.pop.}
+
+

waku/v2/protocol/waku_rln_relay/waku_rln_relay_utils.nim

@@ -1,5 +1,5 @@
 import 
-  chronicles, options, chronos, stint, 
+  chronicles, options, chronos, stint, sequtils,
   web3,
   stew/byteutils,
   eth/keys,
@@ -98,4 +98,12 @@ proc register*(rlnPeer: WakuRLNRelay): Future[bool] {.async.} =
   discard await sender.register(pk).send(MembershipFee)
   # TODO check the receipt and then return true/false
   await web3.close()
-  return true 
+  return true 
+
+proc proofGen*(data: seq[byte]): seq[byte] =
+  # TODO to implement the actual proof generation logic
+  return "proof".toBytes() 
+
+proc proofVrfy*(data, proof: seq[byte]): bool =
+  # TODO to implement the actual proof verification logic
+  return true