jsonwebtoken

What is jsonwebtoken?

The jsonwebtoken npm package is used to implement JSON Web Tokens (JWT) in Node.js applications. JWTs are a compact, URL-safe means of representing claims to be transferred between two parties. The claims in a JWT are encoded as a JSON object that is used as the payload of a JSON Web Signature (JWS) structure or as the plaintext of a JSON Web Encryption (JWE) structure, enabling the claims to be digitally signed or integrity protected with a Message Authentication Code (MAC) and/or encrypted.

What are jsonwebtoken's main functionalities?

Token Signing

This feature allows you to create a digitally signed token. The token consists of a header, a payload, and a signature. The header typically consists of two parts: the type of the token, which is JWT, and the signing algorithm being used, such as HMAC SHA256 or RSA.

{"alg":"HS256","typ":"JWT"}.eyJsub":"1234567890","name":"John Doe","admin":true}.[signature]

Token Verification

This feature is used to verify the signature of an incoming JWT token to ensure that the sender is who they say they are and to ensure that the message wasn't changed along the way.

jwt.verify(token, 'secret', function(err, decoded) { console.log(decoded.foo) // bar })

Token Decoding

This feature allows you to decode a JWT without verifying it. This is useful for cases where you trust the token or have already verified it and just need to read the payload.

jwt.decode(token)

Other packages similar to jsonwebtoken

passport-jwt

A Passport strategy for authenticating with a JSON Web Token. This module lets you authenticate endpoints using a JWT. It is designed to be used with Passport.js. While jsonwebtoken is used for creating and verifying tokens, passport-jwt is used in the context of a web application to protect routes.

jose

JOSE is a comprehensive set of JWT, JWS, and JWE libraries. Compared to jsonwebtoken, it supports a wider range of algorithms and capabilities, including encryption. It is a more complex library that can be used for a broader set of use cases.

README

jsonwebtoken

An implementation of JSON Web Tokens.

This was developed against draft-ietf-oauth-json-web-token-08. It makes use of node-jws

Install

$ npm install jsonwebtoken

Usage

jwt.sign(payload, secretOrPrivateKey, options)

(Synchronous) Returns the JsonWebToken as string

payload could be an literal, buffer or string

secretOrPrivateKey is a string or buffer containing either the secret for HMAC algorithms, or the PEM encoded private key for RSA and ECDSA.

options:

• algorithm (default: HS256)
• expiresInMinutes or expiresInSeconds
• audience
• subject
• issuer
• noTimestamp
• headers

If payload is not a buffer or a string, it will be coerced into a string using JSON.stringify.

If any expiresInMinutes, audience, subject, issuer are not provided, there is no default. The jwt generated won't include those properties in the payload.

Additional headers can be provided via the headers object.

Generated jwts will include an iat claim by default unless noTimestamp is specified.

Setting ignoreExpiration to true will prevent expired tokens from generating an error.

Example

// sign with default (HMAC SHA256)
var jwt = require('jsonwebtoken');
var token = jwt.sign({ foo: 'bar' }, 'shhhhh');

// sign with RSA SHA256
var cert = fs.readFileSync('private.key');  // get private key
var token = jwt.sign({ foo: 'bar' }, cert, { algorithm: 'RS256'});

jwt.verify(token, secretOrPublicKey, [options, callback])

options:

• ignoreExpiration
• audience
• issuer

(Asynchronous) If a callback is supplied, function acts asynchronously. Callback passed the payload decoded if the signature (and optionally expiration, audience, issuer) are valid. If not, it will be passed the error.

(Synchronous) If a callback is not supplied, function acts synchronously. Returns the payload decoded if the signature (and optionally expiration, audience, issuer) are valid. If not, it will throw the error.

token is the JsonWebToken string

secretOrPublicKey is a string or buffer containing either the secret for HMAC algorithms, or the PEM encoded public key for RSA and ECDSA.

options

• audience: if you want to check audience (aud), provide a value here
• issuer: if you want to check issuer (iss), provide a value here

// verify a token symmetric - synchronous
var decoded = jwt.verify(token, 'shhhhh');
console.log(decoded.foo) // bar

// verify a token symmetric
jwt.verify(token, 'shhhhh', function(err, decoded) {
  console.log(decoded.foo) // bar
});

// invalid token - synchronous
try {
  var decoded = jwt.verify(token, 'wrong-secret');
} catch(err) {
  // err
}

// invalid token
jwt.verify(token, 'wrong-secret', function(err, decoded) {
  // err
  // decoded undefined
});

// verify a token asymmetric
var cert = fs.readFileSync('public.pem');  // get public key
jwt.verify(token, cert, function(err, decoded) {
  console.log(decoded.foo) // bar
});

// verify audience
var cert = fs.readFileSync('public.pem');  // get public key
jwt.verify(token, cert, { audience: 'urn:foo' }, function(err, decoded) {
  // if audience mismatch, err == invalid audience
});

// verify issuer
var cert = fs.readFileSync('public.pem');  // get public key
jwt.verify(token, cert, { audience: 'urn:foo', issuer: 'urn:issuer' }, function(err, decoded) {
  // if issuer mismatch, err == invalid issuer
});

jwt.decode(token [, options])

(Synchronous) Returns the decoded payload without verifying if the signature is valid.

token is the JsonWebToken string

options:

• json: force JSON.parse on the payload even if the header doesn't contain "typ":"JWT".

Example

// get the decoded payload ignoring signature, no secretOrPrivateKey needed
var decoded = jwt.decode(token);

Errors & Codes

Possible thrown errors during verification. Error is the first argument of the verification callback.

TokenExpiredError

Thrown error if the token is expired.

Error object:

• name: 'TokenExpiredError'
• message: 'jwt expired'
• expiredAt: [ExpDate]

jwt.verify(token, 'shhhhh', function(err, decoded) {
  if (err) {
    /*
      err = {
        name: 'TokenExpiredError',
        message: 'jwt expired',
        expiredAt: 1408621000
      }
    */
  }
});

JsonWebTokenError

Error object:

• name: 'JsonWebTokenError'
• message:
  • 'jwt malformed'
  • 'jwt signature is required'
  • 'invalid signature'
  • 'jwt audience invalid. expected: [OPTIONS AUDIENCE]'
  • 'jwt issuer invalid. expected: [OPTIONS ISSUER]'

jwt.verify(token, 'shhhhh', function(err, decoded) {
  if (err) {
    /*
      err = {
        name: 'JsonWebTokenError',
        message: 'jwt malformed'
      }
    */
  }
});

Algorithms supported

Array of supported algorithms. The following algorithms are currently supported.

alg Parameter Value	Digital Signature or MAC Algorithm
HS256	HMAC using SHA-256 hash algorithm
HS384	HMAC using SHA-384 hash algorithm
HS512	HMAC using SHA-512 hash algorithm
RS256	RSASSA using SHA-256 hash algorithm
RS384	RSASSA using SHA-384 hash algorithm
RS512	RSASSA using SHA-512 hash algorithm
ES256	ECDSA using P-256 curve and SHA-256 hash algorithm
ES384	ECDSA using P-384 curve and SHA-384 hash algorithm
ES512	ECDSA using P-521 curve and SHA-512 hash algorithm
none	No digital signature or MAC value included

Issue Reporting

If you have found a bug or if you have a feature request, please report them at this repository issues section. Please do not report security vulnerabilities on the public GitHub issue tracker. The Responsible Disclosure Program details the procedure for disclosing security issues.

TODO

• X.509 certificate chain is not checked

Author

Auth0

License

This project is licensed under the MIT license. See the LICENSE file for more info.