JWT LRU Cache

Coverage

JWT is (almost always) a signed token, and signatures are intentionally slow (for good reason). If you're using JWTs to manage stateless authentication or sessions, validations on each request can incur a performance penalty: on the order of a a few ms per request, depending on a few factors.

This implements a simple LRU cache for verifying JWTs. Cache entries are evicted when the validity of the token could have changed (such as if a token is invalid because it's before nbf, or if a valid token has an exp), or in a least-recently-used order when the number of entries grows beyond the default limit.

Example Use

const app = require('express')();
const JwtLruCache = require('jsonwebtoken-lru-cache');

const tokenCache = new JwtLruCache(1024*1024*10, process.env.SECRET, { aud: 'urn:myapp' });

app.get('/sync', (req, res) => {
  const payload = tokenCache.validate(req.query.token);
  res.send(`hello, ${payload.name}`);
});

app.get('/async', async (req, res) => {
  const payload = await tokenCache.validateAsync(req.query.token);
  res.send(`hello, ${payload.name}`);
});

app.get('/callback', (req, res) => {
  tokenCache.validate(req.query.token, false, (err, payload) => {
    if (err) res.send('sorry you are not authenticated');
    else res.send(`hello, ${payload.name}`);
  });
});

Functions

• constructor(numEntries, secret, options) - All options (except complete) need to be set per-cache, not per-call.
• validate(token, complete, callback) - Validates the token. This will block unless callback is passed.
• async validateAsync(token, complete) - Asynchronously validates the token.
• has(token) - Checks if the token is in the cache.