JWT Tokens

issueJWT.js

const base64url = require("base64url");
const crypto = require("crypto");
const signatureFunction = crypto.createSign("RSA-SHA256");
const verifyFunction = crypto.createVerify("RSA-SHA256");
const fs = require("fs");

/**
 * ISSUANCE
 **/

const headerObj = {
  alg: "RS256",
  typ: "JWT",
};

const payloadObj = {
  sub: "1234567890",
  name: "John Doe",
  admin: true,
  iat: 1516239022,
};

const headerObjString = JSON.stringify(headerObj);
const payloadObjString = JSON.stringify(payloadObj);

const base64UrlHeader = base64url(headerObjString);
const base64UrlPayload = base64url(payloadObjString);

signatureFunction.write(base64UrlHeader + "." + base64UrlPayload);
signatureFunction.end();

const PRIV_KEY = fs.readFileSync(__dirname + "/priv_key.pem", "utf8");
const signatureBase64 = signatureFunction.sign(PRIV_KEY, "base64");

const signatureBase64Url = base64url.fromBase64(signatureBase64);

console.log(signatureBase64Url);

// END ISSUANCE

// VERIFICATION
 
const JWT =
  "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWUsImlhdCI6MTUxNjIzOTAyMn0.POstGetfAytaZS82wHcjoTyoqhMyxXiWdR7Nn7A29DNSl0EiXLdwJ6xC6AfgZWF1bOsS_TuYI3OG85AmiExREkrS6tDfTQ2B3WXlrr-wp5AokiRbz3_oB4OxG-W9KcEEbDRcZc0nH3L7LzYptiy1PtAylQGxHTWZXtGz4ht0bAecBgmpdgXMguEIcoqPJ1n3pIWk_dUZegpqx0Lka21H6XxUTxiy8OcaarA8zdnPUnV6AmNP3ecFawIFYdvJB_cm-GvpCSbr8G8y_Mllj8f4x9nBH8pQux89_6gUY618iYv7tuPWBFfEbLxtF2pZS6YC1aSfLQxeNe8djT9YjpvRZA";

const jwtParts = JWT.split(".");

const headerInBase64UrlFormat = jwtParts[0];
const payloadInBase64UrlFormat = jwtParts[1];
const signatureInBase64UrlFormat = jwtParts[2];

verifyFunction.write(headerInBase64UrlFormat + "." + payloadInBase64UrlFormat);
verifyFunction.end();

const jwtSignatureBase64 = base64url.toBase64(signatureInBase64UrlFormat);

const PUB_KEY = fs.readFileSync(__dirname + "/pub_key.pem", "utf8");

const signatureIsValid = verifyFunction.verify(
  PUB_KEY,
  jwtSignatureBase64,
  "base64"
);

console.log(signatureIsValid);

jsonwebtoken.js

const jwt = require('jsonwebtoken');
const fs = require("fs");

const PUB_KEY = fs.readFileSync(__dirname + "/pub_key.pem", "utf8");
const PRIV_KEY = fs.readFileSync(__dirname + "/priv_key.pem", "utf8");

const payloadObj = {
  sub: "1234567890",
  name: "John Doe",
  admin: true,
  iat: 1516239022,
};

const signedJWT = jwt.sign(payloadObj, PRIV_KEY, { algorithm: "RS256" });

jwt.verify(signedJWT, PUB_KEY, { algorithms: ["RS256"] }, (err, payload) => {
  console.log(payload);
});