diff --git a/src/chat/client.nim b/src/chat/client.nim
index 02e2c73..06f2c3f 100644
--- a/src/chat/client.nim
+++ b/src/chat/client.nim
@@ -50,7 +50,7 @@ type KeyEntry* = object
 type Client* = ref object
   ident: Identity
   ds*: WakuClient
-  keyStore: Table[string, KeyEntry]          # Keyed by HexEncoded Public Key
+  keyStore: Table[RemoteKeyIdentifier, seq[KeyEntry]]
   conversations: Table[string, Conversation] # Keyed by conversation ID
   inboundQueue: QueueRef
   isRunning: bool
@@ -77,7 +77,7 @@ proc newClient*(cfg: WakuConfig, ident: Identity): Client {.raises: [IOError,
     var q = QueueRef(queue: newAsyncQueue[ChatPayload](10))
     var c = Client(ident: ident,
                   ds: waku,
-                  keyStore: initTable[string, KeyEntry](),
+                  keyStore: initTable[RemoteKeyIdentifier, seq[KeyEntry]](),
                   conversations: initTable[string, Conversation](),
                   inboundQueue: q,
                   isRunning: false,
@@ -150,18 +150,23 @@ proc notifyDeliveryAck(client: Client, convo: Conversation,
 # Functional
 #################################################
 
+proc cacheInviteKey(self: var Client, key: PrivateKey) =
+
+  let rki_ephemeral = generateRemoteKeyIdentifier(key.getPublicKey())
+
+  self.keyStore[rki_ephemeral] = @[KeyEntry(
+    keyType: "ephemeral",
+    privateKey: key,
+    timestamp: getCurrentTimestamp()
+  )]
+
 proc createIntroBundle*(self: var Client): IntroBundle =
   ## Generates an IntroBundle for the client, which includes
   ## the required information to send a message.
 
   # Create Ephemeral keypair, save it in the key store
   let ephemeralKey = generateKey()
-
-  self.keyStore[ephemeralKey.getPublicKey().bytes().bytesToHex()] = KeyEntry(
-    keyType: "ephemeral",
-    privateKey: ephemeralKey,
-    timestamp: getCurrentTimestamp()
-  )
+  self.cacheInviteKey(ephemeralKey)
 
   result = IntroBundle(
     ident: @(self.ident.getPubkey().bytes()),
diff --git a/src/chat/conversations/private_v1.nim b/src/chat/conversations/private_v1.nim
index 9e8b264..b52c478 100644
--- a/src/chat/conversations/private_v1.nim
+++ b/src/chat/conversations/private_v1.nim
@@ -1,5 +1,3 @@
-
-import blake2
 import chronicles
 import chronos
 import sds
@@ -75,7 +73,7 @@ proc getConvoIdRaw(participants: seq[PublicKey],
   addrs.sort()
   addrs.add(discriminator)
   let raw = addrs.join("|")
-  return utils.hash_func(raw)
+  return utils.hash_func_str(16, raw) 
 
 proc getConvoId*(self: PrivateV1): string =
   return getConvoIdRaw(@[self.owner.getPubkey(), self.participant], self.discriminator)
@@ -83,7 +81,7 @@ proc getConvoId*(self: PrivateV1): string =
 
 proc calcMsgId(self: PrivateV1, msgBytes: seq[byte]): string =
   let s = fmt"{self.getConvoId()}|{msgBytes}"
-  result = getBlake2b(s, 16, "")
+  result = utils.hash_func_str(16, s) 
 
 
 proc encrypt*(convo: PrivateV1, plaintext: var seq[byte]): EncryptedPayload =
diff --git a/src/chat/crypto.nim b/src/chat/crypto.nim
index 1aa4cc5..2e819d7 100644
--- a/src/chat/crypto.nim
+++ b/src/chat/crypto.nim
@@ -1,11 +1,13 @@
-import proto_types
-
-import strformat
 import crypto/ecdh
-import std/[sysrand]
 import results
+import sequtils
+import std/[endians,sysrand]
+import strformat
+import types
 import utils
 
+import proto_types
+
 export PublicKey, PrivateKey, bytes, createRandomKey, loadPrivateKeyFromBytes, loadPublicKeyFromBytes,
        getPublicKey, Dh, Result, get_addr, `$`
 
@@ -33,3 +35,10 @@ proc toHex*(key: PublicKey): string =
 proc `$`*(key: PublicKey): string =
   let byteStr = toHex(key)
   fmt"{byteStr[0..3]}..{byteStr[^4 .. ^1]}"
+
+proc generateRemoteKeyIdentifier*(publicKey: PublicKey): RemoteKeyIdentifier =
+  let bytes = cast[seq[byte]]("WAP") & publicKey.bytes().toSeq()
+  let hash = utils.hash_func_bytes(4,bytes)
+
+  var result: uint32
+  littleEndian32(addr result, unsafeAddr hash[0])
\ No newline at end of file
diff --git a/src/chat/crypto/ecdh.nim b/src/chat/crypto/ecdh.nim
index 8237fbe..0e4f00d 100644
--- a/src/chat/crypto/ecdh.nim
+++ b/src/chat/crypto/ecdh.nim
@@ -15,7 +15,7 @@ proc bytes*(key: PublicKey): array[Curve25519KeySize, byte] =
 
 proc get_addr*(pubkey: PublicKey): string =
     # TODO: Needs Spec
-    result = hash_func(pubkey.bytes().bytesToHex())
+    result = hash_func_str(6,pubkey.bytes().bytesToHex())
 
 
 proc bytes*(key: PrivateKey): Curve25519Key =
diff --git a/src/chat/inbox.nim b/src/chat/inbox.nim
index 7af319a..3f4e8d1 100644
--- a/src/chat/inbox.nim
+++ b/src/chat/inbox.nim
@@ -86,14 +86,14 @@ proc sendFrame(ds: WakuClient, remote: PublicKey, frame: InboxV1Frame ): Future[
 proc newPrivateInvite(initator_static: PublicKey, 
                       initator_ephemeral: PublicKey, 
                       recipient_static: PublicKey, 
-                      recipient_ephemeral: uint32, 
+                      recipient_ephemeral: PublicKey, 
                       payload: EncryptedPayload) : InboxV1Frame =
 
   let invite = InvitePrivateV1(
     initiator: @(initator_static.bytes()),
     initiatorEphemeral: @(initator_ephemeral.bytes()),
     participant: @(recipient_static.bytes()),
-    participantEphemeralId: 0,
+    participantEphemeralId: cast[int32](generateRemoteKeyIdentifier(recipient_ephemeral)),
     discriminator: "",
     initial_message: payload
   )
@@ -115,7 +115,7 @@ proc inviteToPrivateConversation*(self: Inbox, ds: Wakuclient, remote_static: Pu
   result = convo
 
   # # Build Invite
-  let frame = newPrivateInvite(self.identity.getPubkey(), local_ephemeral.getPublicKey(), remote_static, 0, encPayload)
+  let frame = newPrivateInvite(self.identity.getPubkey(), local_ephemeral.getPublicKey(), remote_static, remote_ephemeral, encPayload)
   
   # Send
   await sendFrame(ds, remote_static, frame)
diff --git a/src/chat/types.nim b/src/chat/types.nim
index d5989fd..493a36d 100644
--- a/src/chat/types.nim
+++ b/src/chat/types.nim
@@ -1,2 +1,4 @@
 type MessageId* = string
 type Content* = seq[byte]
+
+type RemoteKeyIdentifier* = uint32
diff --git a/src/chat/utils.nim b/src/chat/utils.nim
index d6b3a26..e02a2b1 100644
--- a/src/chat/utils.nim
+++ b/src/chat/utils.nim
@@ -7,9 +7,16 @@ proc getCurrentTimestamp*(): Timestamp =
     result = waku_core.getNanosecondTime(getTime().toUnix())
 
 
-proc hash_func*(s: string | seq[byte]): string =
-    # This should be Blake2s but it does not exist so substituting with Blake2b
-    result = getBlake2b(s, 4, "")
+proc hash_func_bytes*(n: static range[1..64], s: string | seq[byte]): seq[uint8] =
+
+    let key = ""
+    var b: Blake2b
+    blake2b_init(b, n, cstring(key), len(key))
+    blake2b_update(b, s, len(s))
+    result = blake2b_final(b)
+
+proc hash_func_str*(n: static range[1..64], s: string | seq[byte]): string =
+    result = $hash_func_bytes(n,s)
 
 proc bytesToHex*[T](bytes: openarray[T], lowercase: bool = false): string =
     ## Convert bytes to hex string with case option