diff --git a/src/public/chat.js b/src/public/chat.js
index afb7f56..ceb55c2 100644
--- a/src/public/chat.js
+++ b/src/public/chat.js
@@ -111,8 +111,8 @@ export function create_listener(form, input, messages) {
 function encrypt_message(message, user_pubkey) {
     let encryption_key = sending_ratchets[user_pubkey].next();
     let encoded_msg = (new TextEncoder()).encode(message);
-    let iv = generateRandomUint8Array();
-    let nonce = generateRandomUint8Array();
+    let iv = generateRandomUint8Array(12);
+    let nonce = generateRandomUint8Array(12);
     let associated_data = concatUint8Arrays(fromHexString(user_pubkey), getRoundedUTCTime());
     let {cipher, tag} = keccakAEAD.encrypt(encryption_key, encoded_msg, iv, associated_data, nonce);
     return {cipher: toHexString(cipher),