token.ts

import { createHmac } from "crypto";

const createHash = (secret: string, payload: string): string =>
  createHmac("sha256", secret).update(payload).digest("base64");

export const generateToken = (secret: string, payload: string): string => {
  return createHash(secret, payload) + "$" + payload;
};

export const verifyToken = (secret: string, token: string): string | undefined => {
  const splitToken = token.split("$", 2);

  if (splitToken.length !== 2) {
    return;
  }

  const [hash, payload] = splitToken;

  if (createHash(secret, payload) !== hash) {
    return;
  }

  return payload;
};