JSON Web Encryption (JWE) Token via Direct Encryption Using AES-GCM Secret Key w Node.js Crypto Module

jwe-dir-a256gcm.mjs

import { Buffer } from 'node:buffer';
import fs from "node:fs";
import url from 'node:url';
import path from "node:path";
const {createCipheriv, createDecipheriv, createSecretKey, randomFill, generateKey} = await import('node:crypto');
var aesKey;
var claims = {name:"Joe",roles:["member","admin"]};

(async function () {
  console.log("\x1b[31mInvalid Token")
  aesKey = await generateSecretKey();
  let jwe = await returnJWE(claims);
  console.log("\x1b[37mYour JWE token is: " + consoleString(jwe));
  console.log("Paste JSON Web Token In Terminal Then Press Enter.")
})();

async function decryptJWE(jwe) {
  try {
    let parts = jwe.split(".");
    let encodedJWEProtectedHeader = parts[0];
    let protectedHeaderBuffer = Buffer.from(encodedJWEProtectedHeader,'base64url');
    let cipherText = parts[3];
    let tag = parts[4];
    let tagBuffer = Buffer.from(tag,'base64url');
    let iv = Buffer.from(parts[2],'base64url');
    const decipher = createDecipheriv('aes-256-gcm', aesKey, iv);
    decipher.setAAD(protectedHeaderBuffer);
    decipher.setAuthTag(tagBuffer);
    let decrypted = decipher.update(cipherText,'base64url','utf8');
    decrypted += decipher.final('utf8');
    return JSON.parse(decrypted);
  } catch (e) {
    return "\x1b[31mInvalid Token!\x1b[37m";
  }
}

function generateInitializationVector () {
  return new Promise(function(resolve, reject) {
    let buf = Buffer.alloc(12); //makes 96 bit
    randomFill(buf, (err, buf) => {
      if (err) reject (err);
      resolve(buf);
    });
  });
}

function generateSecretKey () {
  return new Promise(function(resolve, reject) {
    generateKey('aes', { length: 256 }, (err, key) => {
      if (err) {
        reject (err);
      }
      resolve (key)
    });
  });
}

async function returnJWE(claimsObject){
  let headerObject = {"alg":"dir","enc":"A256GCM"}; 
  let headerString = JSON.stringify(headerObject);
  let iv = await generateInitializationVector();
  let claimsString = JSON.stringify(claimsObject);
  let claimsBase64URLEncoded = Buffer.from(claimsString).toString('base64url');
  let cipher = createCipheriv('aes-256-gcm', aesKey, iv);
  cipher.setAAD(Buffer.from(headerString));
  cipher.setAutoPadding();
  let encrypted = cipher.update(claimsString,'utf8','base64url');
  encrypted += cipher.final('base64url');
  let tag = cipher.getAuthTag().toString('base64url');
  let encryptedKey = "";
  let ivString = Buffer.from(iv).toString('base64url');
  let encodedJWEProtectedHeader = Buffer.from(headerString).toString('base64url');
  let result = encodedJWEProtectedHeader + "." + encryptedKey + "." + ivString + "." + encrypted + "." + tag;
  return result;
}

export default {decryptJWE, returnJWE};

process.stdin.setEncoding('utf8');
process.stdin.on('readable', async () => {
  let chunk;
  while ((chunk = process.stdin.read()) !== null) {
    console.log(await decryptJWE(chunk));
  }
});

function consoleString(token){
  let tokenParts = token.split(/(\.)/);
  let colors = ["32m","31m","33m","34m","36m"];
  let color = "\x1b[X";
  let str = ""
  //str += color
  tokenParts.forEach(function(part,index){
    if(part != "."){
      str += color.replace("X",colors.shift())
    }
    str += part;
    str += "\x1b[37m"
  })
  return str;
}