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passport-jwt

passport-jwt

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A Passport strategy for authenticating with a JSON Web Token.

This module lets you authenticate endpoints using a JSON web token. It is intended to be used to secure RESTful endpoints without sessions.

Install

npm install passport-jwt

Usage

Configure Strategy

The JWT authentication strategy is constructed as follows:

new JwtStrategy(options, verify)

options is an object literal containing options to control how the token is extracted from the request or verified.

  • secretOrKey is a string or buffer containing the secret (symmetric) or PEM-encoded public key (asymmetric) for verifying the token's signature. REQUIRED unless secretOrKeyProvider is provided.
  • secretOrKeyProvider is a callback in the format function secretOrKeyProvider(request, rawJwtToken, done), which should call done with a secret or PEM-encoded public key (asymmetric) for the given key and request combination. done accepts arguments in the format function done(err, secret). Note it is up to the implementer to decode rawJwtToken. REQUIRED unless secretOrKey is provided.
  • jwtFromRequest (REQUIRED) Function that accepts a request as the only parameter and returns either the JWT as a string or null. See Extracting the JWT from the request for more details.
  • issuer: If defined the token issuer (iss) will be verified against this value.
  • audience: If defined, the token audience (aud) will be verified against this value.
  • algorithms: List of strings with the names of the allowed algorithms. For instance, ["HS256", "HS384"].
  • ignoreExpiration: if true do not validate the expiration of the token.
  • passReqToCallback: If true the request will be passed to the verify callback. i.e. verify(request, jwt_payload, done_callback).
  • jsonWebTokenOptions: passport-jwt is verifying the token using jsonwebtoken. Pass here an options object for any other option you can pass the jsonwebtoken verifier. (i.e maxAge)

verify is a function with the parameters verify(jwt_payload, done)

  • jwt_payload is an object literal containing the decoded JWT payload.
  • done is a passport error first callback accepting arguments done(error, user, info)

An example configuration which reads the JWT from the http Authorization header with the scheme 'bearer':

var JwtStrategy = require('passport-jwt').Strategy,
    ExtractJwt = require('passport-jwt').ExtractJwt;
var opts = {}
opts.jwtFromRequest = ExtractJwt.fromAuthHeaderAsBearerToken();
opts.secretOrKey = 'secret';
opts.issuer = 'accounts.examplesoft.com';
opts.audience = 'yoursite.net';
passport.use(new JwtStrategy(opts, function(jwt_payload, done) {
    User.findOne({id: jwt_payload.sub}, function(err, user) {
        if (err) {
            return done(err, false);
        }
        if (user) {
            return done(null, user);
        } else {
            return done(null, false);
            // or you could create a new account 
        }
    });
}));

Extracting the JWT from the request

There are a number of ways the JWT may be included in a request. In order to remain as flexible as possible the JWT is parsed from the request by a user-supplied callback passed in as the jwtFromRequest parameter. This callback, from now on referred to as an extractor, accepts a request object as an argument and returns the encoded JWT string or null.

Included extractors

A number of extractor factory functions are provided in passport-jwt.ExtractJwt. These factory functions return a new extractor configured with the given parameters.

  • fromHeader(header_name) creates a new extractor that looks for the JWT in the given http header
  • fromBodyField(field_name) creates a new extractor that looks for the JWT in the given body field. You must have a body parser configured in order to use this method.
  • fromUrlQueryParameter(param_name) creates a new extractor that looks for the JWT in the given URL query parameter.
  • fromAuthHeaderWithScheme(auth_scheme) creates a new extractor that looks for the JWT in the authorization header, expecting the scheme to match auth_scheme.
  • fromAuthHeaderAsBearerToken() creates a new extractor that looks for the JWT in the authorization header with the scheme 'bearer'
  • fromExtractors([array of extractor functions]) creates a new extractor using an array of extractors provided. Each extractor is attempted in order until one returns a token.

Writing a custom extractor function

If the supplied extractors don't meet your needs you can easily provide your own callback. For example, if you are using the cookie-parser middleware and want to extract the JWT in a cookie you could use the following function as the argument to the jwtFromRequest option:

var cookieExtractor = function(req) {
    var token = null;
    if (req && req.cookies)
    {
        token = req.cookies['jwt'];
    }
    return token;
};

Authenticate requests

Use passport.authenticate() specifying 'JWT' as the strategy.

app.post('/profile', passport.authenticate('jwt', { session: false }),
    function(req, res) {
        res.send(req.user.profile);
    }
);

Include the JWT in requests

The strategy will first check the request for the standard Authorization header. If this header is present and the scheme matches options.authScheme or 'JWT' if no auth scheme was specified then the token will be retrieved from it. e.g.

Authorization: JWT JSON_WEB_TOKEN_STRING.....

If the authorization header with the expected scheme is not found, the request body will be checked for a field matching either options.tokenBodyField or auth_token if the option was not specified.

Finally, the URL query parameters will be checked for a field matching either options.tokenQueryParameterName or auth_token if the option was not specified.

Migrating from 2.x.x to 3.x.x

Version 3.0.0 removes the ExtractJwt.fromAuthHeader() extractor function that would extract JWT's from Authorization headers with the auth scheme 'jwt'. The default authorization scheme of 'jwt' as the was not RFC 6750 compliant. The extractor was replaced with ExtractJwt.fromAuthHeaderAsBearerToken(). The removal of ExtractJwt.fromAuthHeader() was done to clearly change the API so any code relying on the old API would clearly break, hopefully saving people some debugging time.

If you want to maintain the behavior of ExtractJwt.fromAuthHeader() when switching to v3.3.0, simply replace it with ExtractJwt.fromAuthHeaderWithScheme('jwt') in your implementation.

Migrating from version 1.x.x to 2.x.x

See the guide for migrating from v1 to v2 for explanation of the major changes.

Tests

npm install
npm test

To generate test-coverage reports:

npm install -g istanbul
npm run-script testcov
istanbul report

License

The MIT License

Copyright (c) 2015 Mike Nicholson