diff --git a/library/api/client_api.nim b/library/api/client_api.nim
index 99b147b..24b80ce 100644
--- a/library/api/client_api.nim
+++ b/library/api/client_api.nim
@@ -63,6 +63,8 @@ proc createChatClient(
       wakuCfg.minMixPoolSize = config["minMixPoolSize"].getInt(4)
     if config.hasKey("gifterNodeAddr"):
       wakuCfg.gifterNodeAddr = config["gifterNodeAddr"].getStr("")
+    if config.hasKey("gifterAuthKey"):
+      wakuCfg.gifterAuthKey = config["gifterAuthKey"].getStr("")
 
     # Create Waku client
     let wakuClient = initWakuClient(wakuCfg)
diff --git a/simulations/mix_lez_chat/fixtures/gifter_auth/.build/derive_addr b/simulations/mix_lez_chat/fixtures/gifter_auth/.build/derive_addr
deleted file mode 100755
index 9868e2f..0000000
Binary files a/simulations/mix_lez_chat/fixtures/gifter_auth/.build/derive_addr and /dev/null differ
diff --git a/simulations/mix_lez_chat/fixtures/gifter_auth/addresses.env b/simulations/mix_lez_chat/fixtures/gifter_auth/addresses.env
new file mode 100644
index 0000000..e332d02
--- /dev/null
+++ b/simulations/mix_lez_chat/fixtures/gifter_auth/addresses.env
@@ -0,0 +1,6 @@
+# Ethereum addresses derived from keys.env. Keep in sync if those keys change.
+ADDR_MIX1=0x8ba6d3237e6f2c84b0e3d71aa57bc5869d3b5218
+ADDR_MIX2=0x8e3d4d0a713087e2263e2fcdec894c283c777dcc
+ADDR_MIX3=0xca282bbf8bf3636e15af3ad8caf11cdd38bf35d8
+ADDR_SENDER=0x0b6872aaae7a2d4f3c701793cde57b93337f4d4a
+ADDR_RECEIVER=0xb5dda07309f5ab06e0847f6036c305ea9ae26937
diff --git a/simulations/mix_lez_chat/fixtures/gifter_auth/keys.env b/simulations/mix_lez_chat/fixtures/gifter_auth/keys.env
new file mode 100644
index 0000000..8771130
--- /dev/null
+++ b/simulations/mix_lez_chat/fixtures/gifter_auth/keys.env
@@ -0,0 +1,9 @@
+# Test fixtures for the RLN gifter EIP-191 auth path. NOT FOR PRODUCTION.
+# Each value is a 64-hex-char secp256k1 private key. addresses.env holds
+# the corresponding Ethereum addresses; if these keys change, regenerate
+# the addresses (any keccak256(secp256k1 pubkey)[12:] tool will do).
+KEY_MIX1=2c974e0a453f65dd2230d403f6981fc18f9a3ad7675afb647910e0798a3eaa4f
+KEY_MIX2=b880df1f571109e646f641636794dfe7ffefc2aab19290ba0d720c407758304d
+KEY_MIX3=0b1b5e18839a3e15b119519092e4a94a71122acf57d8b2e1014df0121cb6f0ea
+KEY_SENDER=5284ac01fed5fcb6b26933ac4a901412b66fcd7ee5b945b799f147a3b42f49ef
+KEY_RECEIVER=a5619d6bfde09f54165ec9da55a7be7380f1b258c8279177dbda5ac235d0e904
diff --git a/simulations/mix_lez_chat/run_simulation.sh b/simulations/mix_lez_chat/run_simulation.sh
index 4366e87..b44f788 100755
--- a/simulations/mix_lez_chat/run_simulation.sh
+++ b/simulations/mix_lez_chat/run_simulation.sh
@@ -179,6 +179,16 @@ CONFIG_ACCOUNT=$(echo "$SETUP_OUTPUT" | grep -oE 'Config account:\s+\S+' | awk '
 GIFTER_ACCOUNT=$(cat "$GIFTER_ACCOUNT_FILE" 2>/dev/null || true)
 [ -z "$GIFTER_ACCOUNT" ] && die "Gifter account not found at $GIFTER_ACCOUNT_FILE"
 
+# EIP-191 auth fixtures: per-process secp256k1 keys and the allowlist installed
+# on the gifter (mix node 0). Keys are committed test fixtures — not for prod.
+GIFTER_AUTH_DIR="$SCRIPT_DIR/fixtures/gifter_auth"
+# shellcheck disable=SC1091
+source "$GIFTER_AUTH_DIR/keys.env"
+# shellcheck disable=SC1091
+source "$GIFTER_AUTH_DIR/addresses.env"
+GIFTER_ALLOWLIST="$ADDR_MIX1,$ADDR_MIX2,$ADDR_MIX3,$ADDR_SENDER,$ADDR_RECEIVER"
+echo "  Gifter allowlist: $GIFTER_ALLOWLIST"
+
 # ---------- Phase 3: Prerequisites ----------
 echo "[3/6] Verifying prerequisites..."
 LOGOSCORE="${LOGOSCORE:-$(nix build github:logos-co/logos-liblogos/7df6195 --override-input logos-cpp-sdk github:logos-co/logos-cpp-sdk/a4bd66c --no-link --print-out-paths)/bin/logoscore}"
@@ -238,9 +248,11 @@ for i in $(seq 0 $((NUM_NODES - 1))); do
 
     GIFTER_FIELDS=""
     if [ "$i" -eq 0 ]; then
-        GIFTER_FIELDS="\"mixGifterService\": true, \"mixGifterWalletAccount\": \"$GIFTER_ACCOUNT\","
+        GIFTER_FIELDS="\"mixGifterService\": true, \"mixGifterWalletAccount\": \"$GIFTER_ACCOUNT\", \"mixGifterAllowlist\": \"$GIFTER_ALLOWLIST\","
     else
-        GIFTER_FIELDS="\"mixGifterNode\": \"$BOOTSTRAP_PEER\", \"mixGifterWalletAccount\": \"$GIFTER_ACCOUNT\","
+        # KEY_MIX1..3 align with non-gifter nodes 1..3.
+        AUTH_KEY_VAR="KEY_MIX$i"
+        GIFTER_FIELDS="\"mixGifterNode\": \"$BOOTSTRAP_PEER\", \"mixGifterWalletAccount\": \"$GIFTER_ACCOUNT\", \"mixGifterAuthKey\": \"${!AUTH_KEY_VAR}\","
     fi
 
     cat > "$NODE_CONFIG" <<EOF
@@ -402,6 +414,7 @@ cat > "$RECV_CONFIG" <<EOF
   "destPeerAddr": "$BOOTSTRAP_PEER",
   "minMixPoolSize": 4,
   "gifterNodeAddr": "$BOOTSTRAP_PEER",
+  "gifterAuthKey": "$KEY_RECEIVER",
   "staticPeers": [$CHAT_STATIC_PEERS]
 }
 EOF
@@ -470,6 +483,7 @@ cat > "$SEND_CONFIG" <<EOF
   "destPeerAddr": "$BOOTSTRAP_PEER",
   "minMixPoolSize": 4,
   "gifterNodeAddr": "$BOOTSTRAP_PEER",
+  "gifterAuthKey": "$KEY_SENDER",
   "staticPeers": [$CHAT_STATIC_PEERS]
 }
 EOF
diff --git a/src/chat/delivery/waku_client.nim b/src/chat/delivery/waku_client.nim
index dd010d3..bb91d6c 100644
--- a/src/chat/delivery/waku_client.nim
+++ b/src/chat/delivery/waku_client.nim
@@ -2,6 +2,8 @@ import
   chronicles,
   chronos,
   confutils,
+  eth/common/addresses as eth_addresses,
+  eth/common/keys as eth_keys,
   eth/p2p/discoveryv5/enr as eth_enr,
   libp2p/crypto/crypto,
   libp2p/crypto/curve25519,
@@ -104,6 +106,7 @@ type WakuConfig* = object
   destPeerAddr*: string
   minMixPoolSize*: int
   gifterNodeAddr*: string
+  gifterAuthKey*: string
 
 type
   WakuClient* = ref object
@@ -125,7 +128,8 @@ proc DefaultConfig*(): WakuConfig =
       shardId: @[shardId], pubsubTopic: &"/waku/2/rs/{clusterId}/{shardId}",
           staticPeers: LogosDevStaticPeers,
           mixEnabled: false, mixNodes: @[], destPeerAddr: "", minMixPoolSize: 4,
-          gifterNodeAddr: "")
+          gifterNodeAddr: "",
+          gifterAuthKey: "")
 
 
 proc sendBytes*(client: WakuClient, contentTopic: string,
@@ -376,8 +380,18 @@ proc start*(client: WakuClient) {.async.} =
         gifterPeer = client.cfg.gifterNodeAddr,
         idCommitment = idCommitmentHex[0 .. 15] & "..."
 
+      var authPayload = none(seq[byte])
+      if client.cfg.gifterAuthKey.len > 0:
+        let seckey = eth_keys.PrivateKey.fromHex(client.cfg.gifterAuthKey).valueOr:
+          error "Failed to parse gifter auth key", error = $error
+          quit(QuitFailure)
+        let sig = seckey.sign(rln_gifter_protocol.eip191Message(idCommitmentHex))
+        authPayload = some(@(sig.toRaw()))
+        info "Signing gifter request with EIP-191 auth key",
+          signer = seckey.toPublicKey().to(eth_addresses.Address).to0xHex()
+
       let regRes = await gifterClient.requestMembership(
-        idCommitmentHex, uint64(lezGm.userMessageLimit), gifterPeer
+        idCommitmentHex, uint64(lezGm.userMessageLimit), gifterPeer, authPayload
       )
       if regRes.isErr:
         error "Failed to register via gifter", error = regRes.error
diff --git a/vendor/logos-lez-rln b/vendor/logos-lez-rln
index f3f1aa6..6f0c33e 160000
--- a/vendor/logos-lez-rln
+++ b/vendor/logos-lez-rln
@@ -1 +1 @@
-Subproject commit f3f1aa6c609fae776712e04ccf0aa5a64f004391
+Subproject commit 6f0c33ea3846d89b615a053edf38ffc2768d091f
diff --git a/vendor/nwaku b/vendor/nwaku
index 48065f7..41d73f9 160000
--- a/vendor/nwaku
+++ b/vendor/nwaku
@@ -1 +1 @@
-Subproject commit 48065f7d703568dbc458abf9432a63adc2e80b33
+Subproject commit 41d73f92eb4e7810f830d18e8634d72759472936