Whisper
your secrets.

async def send_chat_message(
    self, contact_name, text,
    reply_to=0, react_to=0
):
    async with self._get_contact_lock(contact_name):
        contact = self.db.get_contact(contact_name)

        send_chain_hex = contact.get(
            "send_chain_key_hex", ""
        )
        send_chain = bytes.fromhex(send_chain_hex)
        counter = contact.get(
            "send_counter", 0
        ) + 1

        msg_key = chain_message_key(send_chain)
        padded = pad_message(text.encode("utf-8"))
        nonce = os.urandom(12)
        aad = f"{self.user_name}:{counter}".encode("utf-8")
        ct = aes_gcm_encrypt(
            msg_key, padded, nonce, aad
        )

        signed_data = (
            self.user_name.encode("utf-8")
            + counter.to_bytes(8, "big")
            + nonce + ct
        )
        sig = sign_bytes(self.ed_private, signed_data)
        new_chain = chain_advance(send_chain)

        self.db.set_contact_state(
            contact_name,
            send_chain_key_hex=new_chain.hex(),
            send_counter=counter
        )