feat(waku-stealth-commitments): waku stealth commitment protocol (#2490)

* feat(waku-stealth-commitments): initialize app

* feat: works!

* fix: readme

* feat: send and receive, handle received stealth commitment

* fix: remove empty lines

* chore: move to examples

examples/wakustealthcommitments/README.md

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+# wakustealthcommitments
+
+This application/tool/protocol is used to securely communicate requests and responses for the [Stealth Address Scheme](https://eips.ethereum.org/EIPS/eip-5564)
+
+Uses TWN config as default, and content topic: `/wakustealthcommitments/1/app/proto`
+
+## Usage
+
+1. Clone the erc-5564-bn254 repo and build the static lib
+```sh
+gh repo clone rymnc/erc-5564-bn254
+cd erc-5564-bn254
+cargo build --release --all-features
+cp ./target/release/liberc_5564_bn254.a <path-to-nwaku>
+```
+
+> ![NOTE]
+> This static library also includes the rln ffi library, so you don't need to build it separately.
+> This is because using both of them separately brings in a lot of duplicate symbols.
+
+2. Build the wakustealthcommitments app
+```sh
+cd <path-to-nwaku>
+source env.sh
+nim c --out:build/wakustealthcommitments  --verbosity:0 --hints:off -d:chronicles_log_level=INFO -d:git_version="v0.24.0-rc.0-62-g7da25c" -d:release --passL:-lm --passL:liberc_5564_bn254.a --debugger:native examples/wakustealthcommitments/wakustealthcommitments.nim
+```
+
+3. 
+```sh
+./build/wakustealthcommitments \
+    --rln-relay-eth-client-address:<insert http rpc url> \
+    --rln-relay-cred-path:<path-to-credentials-file> \
+    --rln-relay-cred-password:<password-of-credentials-file>
+```
+
+This service listens for requests for stealth commitment/address generation, 
+partakes in the generation of said stealth commitment and then distributes the response to the mesh.
+

examples/wakustealthcommitments/erc_5564_interface.nim

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+## Nim wrappers for the functions defined in librln
+when (NimMajor, NimMinor) < (1, 4):
+  {.push raises: [Defect].}
+else:
+  {.push raises: [].}
+
+import stew/results
+
+######################################################################
+## ERC-5564-BN254 module APIs
+######################################################################
+
+type CErrorCode* = uint8
+
+type CG1Projective* = object
+  x0: array[32, uint8]
+
+type CReturn*[T] = object
+  value: T
+  err_code: CErrorCode
+
+type CFr* = object
+  x0: array[32, uint8]
+
+type CStealthCommitment* = object
+  stealth_commitment: CG1Projective
+  view_tag: uint64
+
+type CKeyPair* = object
+  private_key: CFr
+  public_key: CG1Projective
+
+proc drop_ffi_derive_public_key*(ptrx: ptr CReturn[CG1Projective]) {.importc: "drop_ffi_derive_public_key".}
+
+proc drop_ffi_generate_random_fr*(ptrx: ptr CReturn[CFr]) {.importc: "drop_ffi_generate_random_fr".}
+
+proc drop_ffi_generate_stealth_commitment*(ptrx: ptr CReturn[CStealthCommitment]) {.importc: "drop_ffi_generate_stealth_commitment".}
+
+proc drop_ffi_generate_stealth_private_key*(ptrx: ptr CReturn[CFr]) {.importc: "drop_ffi_generate_stealth_private_key".}
+
+proc drop_ffi_random_keypair*(ptrx: ptr CReturn[CKeyPair]) {.importc: "drop_ffi_random_keypair".}
+
+proc ffi_derive_public_key*(private_key: ptr CFr): (ptr CReturn[CG1Projective]) {.importc: "ffi_derive_public_key".}
+
+proc ffi_generate_random_fr*(): (ptr CReturn[CFr]) {.importc: "ffi_generate_random_fr".}
+
+proc ffi_generate_stealth_commitment*(viewing_public_key: ptr CG1Projective,
+                                      spending_public_key: ptr CG1Projective,
+                                      ephemeral_private_key: ptr CFr): (ptr CReturn[CStealthCommitment]) {.importc: "ffi_generate_stealth_commitment".}
+
+proc ffi_generate_stealth_private_key*(ephemeral_public_key: ptr CG1Projective,
+                                       spending_key: ptr CFr,
+                                       viewing_key: ptr CFr,
+                                       view_tag: ptr uint64): (ptr CReturn[CFr]) {.importc: "ffi_generate_stealth_private_key".}
+
+proc ffi_random_keypair*(): (ptr CReturn[CKeyPair]) {.importc: "ffi_random_keypair".}
+
+
+## Nim wrappers and types for the ERC-5564-BN254 module
+
+type FFIResult[T] = Result[T, string]
+type Fr = array[32, uint8]
+type G1Projective = array[32, uint8]
+type KeyPair* = object
+  private_key*: Fr
+  public_key*: G1Projective
+type StealthCommitment* = object
+  stealth_commitment*: G1Projective
+  view_tag*: uint64
+type PrivateKey* = Fr
+type PublicKey* = G1Projective
+
+proc generateRandomFr*(): FFIResult[Fr] =
+  let res_ptr = (ffi_generate_random_fr())
+  let res_value = res_ptr[]
+  if res_value.err_code != 0:
+    drop_ffi_generate_random_fr(res_ptr)
+    return err("Error generating random field element: " & $res_value.err_code)
+
+  let ret = res_value.value.x0
+  drop_ffi_generate_random_fr(res_ptr)
+  return ok(ret)
+
+proc generateKeypair*(): FFIResult[KeyPair] =
+  let res_ptr = (ffi_random_keypair())
+  let res_value = res_ptr[]
+  if res_value.err_code != 0:
+    drop_ffi_random_keypair(res_ptr)
+    return err("Error generating random keypair: " & $res_value.err_code)
+
+  let ret = KeyPair(private_key: res_value.value.private_key.x0, public_key: res_value.value.public_key.x0)
+  drop_ffi_random_keypair(res_ptr)
+  return ok(ret)
+
+proc generateStealthCommitment*(viewing_public_key: G1Projective,
+                                spending_public_key: G1Projective,
+                                ephemeral_private_key: Fr): FFIResult[StealthCommitment] =
+  let viewing_public_key = CG1Projective(x0: viewing_public_key)
+  let viewing_public_key_ptr = unsafeAddr(viewing_public_key)
+  let spending_public_key = CG1Projective(x0: spending_public_key)
+  let spending_public_key_ptr = unsafeAddr(spending_public_key)
+  let ephemeral_private_key = CFr(x0: ephemeral_private_key)
+  let ephemeral_private_key_ptr = unsafeAddr(ephemeral_private_key)
+
+  let res_ptr = (ffi_generate_stealth_commitment(viewing_public_key_ptr, spending_public_key_ptr, ephemeral_private_key_ptr))
+  let res_value = res_ptr[]
+  if res_value.err_code != 0:
+    drop_ffi_generate_stealth_commitment(res_ptr)
+    return err("Error generating stealth commitment: " & $res_value.err_code)
+
+  let ret = StealthCommitment(stealth_commitment: res_value.value.stealth_commitment.x0, view_tag: res_value.value.view_tag)
+  drop_ffi_generate_stealth_commitment(res_ptr)
+  return ok(ret)
+
+proc generateStealthPrivateKey*(ephemeral_public_key: G1Projective,
+                                spending_key: Fr,
+                                viewing_key: Fr,
+                                view_tag: uint64): FFIResult[Fr] =
+  let ephemeral_public_key = CG1Projective(x0: ephemeral_public_key)
+  let ephemeral_public_key_ptr = unsafeAddr(ephemeral_public_key)
+  let spending_key = CFr(x0: spending_key)
+  let spending_key_ptr = unsafeAddr(spending_key)
+  let viewing_key = CFr(x0: viewing_key)
+  let viewing_key_ptr = unsafeAddr(viewing_key)
+  let view_tag_ptr = unsafeAddr(view_tag)
+
+  let res_ptr = (ffi_generate_stealth_private_key(ephemeral_public_key_ptr, spending_key_ptr, viewing_key_ptr, view_tag_ptr))
+  let res_value = res_ptr[]
+  if res_value.err_code != 0:
+    drop_ffi_generate_stealth_private_key(res_ptr)
+    return err("Error generating stealth private key: " & $res_value.err_code)
+
+  let ret = res_value.value.x0
+  drop_ffi_generate_stealth_private_key(res_ptr)
+  return ok(ret)

examples/wakustealthcommitments/nim.cfg

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+-d:chronicles_line_numbers
+-d:discv5_protocol_id="d5waku"
+-d:chronicles_runtime_filtering=on
+-d:chronicles_sinks="textlines,json"
+-d:chronicles_default_output_device=dynamic
+# Disabling the following topics from nim-eth and nim-dnsdisc since some types cannot be serialized
+-d:chronicles_disabled_topics="eth,dnsdisc.client"
+-d:chronicles_log_level=INFO
+# Results in empty output for some reason
+#-d:"chronicles_enabled_topics=GossipSub:TRACE,WakuRelay:TRACE"

examples/wakustealthcommitments/node_spec.nim

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+when (NimMajor, NimMinor) < (1, 4):
+  {.push raises: [Defect].}
+else:
+  {.push raises: [].}
+
+import ../../apps/wakunode2/[networks_config, app, external_config]
+import ../../waku/common/logging
+import
+  std/[options, strutils, os, sequtils],
+  stew/shims/net as stewNet,
+  chronicles,
+  chronos,
+  metrics,
+  libbacktrace,
+  libp2p/crypto/crypto
+
+export
+  networks_config,
+  app,
+  logging,
+  options, 
+  strutils, 
+  os, 
+  sequtils,
+  stewNet,
+  chronicles,
+  chronos,
+  metrics,
+  libbacktrace,
+  crypto
+
+proc setup*(): App =
+  const versionString = "version / git commit hash: " & app.git_version
+  let rng = crypto.newRng()
+
+  let confRes = WakuNodeConf.load(version = versionString)
+  if confRes.isErr():
+    error "failure while loading the configuration", error = $confRes.error
+    quit(QuitFailure)
+
+  var conf = confRes.get()
+
+  let twnClusterConf = ClusterConf.TheWakuNetworkConf()
+  if len(conf.shards) != 0:
+    conf.pubsubTopics = conf.shards.mapIt(twnClusterConf.pubsubTopics[it.uint16])
+  else:
+    conf.pubsubTopics = twnClusterConf.pubsubTopics
+
+  # Override configuration
+  conf.maxMessageSize = twnClusterConf.maxMessageSize
+  conf.clusterId = twnClusterConf.clusterId
+  conf.rlnRelay = twnClusterConf.rlnRelay
+  conf.rlnRelayEthContractAddress = twnClusterConf.rlnRelayEthContractAddress
+  conf.rlnRelayDynamic = twnClusterConf.rlnRelayDynamic
+  conf.rlnRelayBandwidthThreshold = twnClusterConf.rlnRelayBandwidthThreshold
+  conf.discv5Discovery = twnClusterConf.discv5Discovery
+  conf.discv5BootstrapNodes =
+    conf.discv5BootstrapNodes & twnClusterConf.discv5BootstrapNodes
+  conf.rlnEpochSizeSec = twnClusterConf.rlnEpochSizeSec
+  conf.rlnRelayUserMessageLimit = twnClusterConf.rlnRelayUserMessageLimit
+
+  var wakunode2 = App.init(rng, conf)
+  ## Peer persistence
+  let res1 = wakunode2.setupPeerPersistence()
+  if res1.isErr():
+    error "1/5 Setting up storage failed", error = $res1.error
+    quit(QuitFailure)
+
+  debug "2/5 Retrieve dynamic bootstrap nodes"
+
+  let res3 = wakunode2.setupDyamicBootstrapNodes()
+  if res3.isErr():
+    error "2/5 Retrieving dynamic bootstrap nodes failed", error = $res3.error
+    quit(QuitFailure)
+
+  debug "3/5 Initializing node"
+
+  let res4 = wakunode2.setupWakuApp()
+  if res4.isErr():
+    error "3/5 Initializing node failed", error = $res4.error
+    quit(QuitFailure)
+
+  debug "4/5 Mounting protocols"
+
+  var res5: Result[void, string]
+  try:
+    res5 = waitFor wakunode2.setupAndMountProtocols()
+    if res5.isErr():
+      error "4/5 Mounting protocols failed", error = $res5.error
+      quit(QuitFailure)
+  except Exception:
+    error "4/5 Mounting protocols failed", error = getCurrentExceptionMsg()
+    quit(QuitFailure)
+
+  debug "5/5 Starting node and mounted protocols"
+
+  # set triggerSelf to false, we don't want to process our own stealthCommitments
+  wakunode2.node.wakuRelay.triggerSelf = false
+
+  let res6 = wakunode2.startApp()
+  if res6.isErr():
+    error "5/5 Starting node and protocols failed", error = $res6.error
+    quit(QuitFailure)
+
+  info "Node setup complete"
+  return wakunode2