examples.waku.org/eth-pm/src/BroadcastPublicKey.tsx

import { Button } from "@material-ui/core";
import React, { useState } from "react";
import {
  createPublicKeyMessage,
  KeyPair,
  PublicKeyMessageEncryptionKey,
} from "./crypto";
import { PublicKeyMessage } from "./messaging/wire";
import { WakuMessage } from "js-waku";
import { WakuLight } from "js-waku/lib/interfaces";
import { PublicKeyContentTopic } from "./waku";
import type { TypedDataSigner } from "@ethersproject/abstract-signer";

interface Props {
  EncryptionKeyPair: KeyPair | undefined;
  waku: WakuLight | undefined;
  address: string | undefined;
  signer: TypedDataSigner | undefined;
}

export default function BroadcastPublicKey({
  EncryptionKeyPair,
  waku,
  address,
  signer,
}: Props) {
  const [publicKeyMsg, setPublicKeyMsg] = useState<PublicKeyMessage>();

  const broadcastPublicKey = () => {
    if (!EncryptionKeyPair) return;
    if (!address) return;
    if (!waku) return;
    if (!signer) return;

    if (publicKeyMsg) {
      encodePublicKeyWakuMessage(publicKeyMsg)
        .then((wakuMsg) => {
          waku.lightPush.push(wakuMsg).catch((e) => {
            console.error("Failed to send Public Key Message", e);
          });
        })
        .catch((e) => {
          console.log("Failed to encode Public Key Message in Waku Message", e);
        });
    } else {
      createPublicKeyMessage(address, EncryptionKeyPair.publicKey, signer)
        .then((msg) => {
          setPublicKeyMsg(msg);
          encodePublicKeyWakuMessage(msg)
            .then((wakuMsg) => {
              waku.lightPush
                .push(wakuMsg)
                .then((res) => console.log("Public Key Message pushed", res))
                .catch((e) => {
                  console.error("Failed to send Public Key Message", e);
                });
            })
            .catch((e) => {
              console.log(
                "Failed to encode Public Key Message in Waku Message",
                e
              );
            });
        })
        .catch((e) => {
          console.error("Failed to create public key message", e);
        });
    }
  };

  return (
    <Button
      variant="contained"
      color="primary"
      onClick={broadcastPublicKey}
      disabled={!EncryptionKeyPair || !waku || !address || !signer}
    >
      Broadcast Encryption Public Key
    </Button>
  );
}

async function encodePublicKeyWakuMessage(
  publicKeyMessage: PublicKeyMessage
): Promise<WakuMessage> {
  const payload = publicKeyMessage.encode();
  return await WakuMessage.fromBytes(payload, PublicKeyContentTopic, {
    symKey: PublicKeyMessageEncryptionKey,
  });
}