Verify signature of a signed message

verify_signature_solana-v1.txt

// sign a message with a wallet private key and validate its signature
// https://github.com/0xC0A1/web3-auth/tree/master

import { useEffect } from "react";
import b58 from "bs58";
import nacl from "tweetnacl";
import { PublicKey } from "@solana/web3.js";
import { useWallet } from "@solana/wallet-adapter-react";

export const Sign = () => {
  const { signMessage, publicKey } = useWallet();

  const getSignature = async (str: string) => {
    const encodedMessage = new TextEncoder().encode(str);
    const signature = await signMessage(encodedMessage);
    const pk = publicKey.toBase58();
    const msg = b58.encode(encodedMessage);
    const sig = b58.encode(signature);
    return `${pk}.${msg}.${sig}`;
  };

  const verifySignature = async (authToken: string) => {
    const [pk, msg, sig] = authToken.split(".");
    const hasValidSig = nacl.sign.detached.verify(
      b58.decode(msg),
      b58.decode(sig),
      new PublicKey(pk).toBytes()
    );
    return hasValidSig;
  };

  useEffect(() => {
    if (publicKey) {
      getSignature("hello world")
        .then((signature) => {
          console.log("signature", signature);
          // verify signature
          return verifySignature(signature);
        })
        .then((isValid) => {
          console.log("is signature valid", isValid);
        })
        .catch((e) => console.error("error getting signature", e));
    }
  }, [publicKey]);

  return null;
};