JSON Web Token implementation (symmetric and asymmetric)
npm install sc-jsonwebtokendraft-ietf-oauth-json-web-token-08. It makes use of node-jws
bash
$ npm install sc-jsonwebtoken
`
Usage
$3
(Asynchronous) If a callback is supplied, callback is called with the err or the JWT.
(Synchronous) Returns the JsonWebToken as string
payload could be an object literal, buffer or string. Please note that exp is only set if the payload is an object literal.
secretOrPrivateKey is a string, buffer, or object containing either the secret for HMAC algorithms or the PEM
encoded private key for RSA and ECDSA. In case of a private key with passphrase an object { key, passphrase } can be used (based on crypto documentation), in this case be sure you pass the algorithm option.
options:
* algorithm (default: HS256)
* expiresIn: expressed in seconds or a string describing a time span zeit/ms. Eg: 60, "2 days", "10h", "7d"
* notBefore: expressed in seconds or a string describing a time span zeit/ms. Eg: 60, "2 days", "10h", "7d"
* audience
* issuer
* jwtid
* subject
* noTimestamp
* header
If payload is not a buffer or a string, it will be coerced into a string using JSON.stringify.
There are no default values for expiresIn, notBefore, audience, subject, issuer. These claims can also be provided in the payload directly with exp, nbf, aud, sub and iss respectively, but you can't include in both places.
Remember that exp, nbf and iat are NumericDate, see related Token Expiration (exp claim)
The header can be customized via the option.header object.
Generated jwts will include an iat (issued at) claim by default unless noTimestamp is specified. If iat is inserted in the payload, it will be used instead of the real timestamp for calculating other things like exp given a timespan in options.expiresIn.
Example
`js
// sign with default (HMAC SHA256)
var jwt = require('sc-jsonwebtoken');
var token = jwt.sign({ foo: 'bar' }, 'shhhhh');
//backdate a jwt 30 seconds
var older_token = jwt.sign({ foo: 'bar', iat: Math.floor(Date.now() / 1000) - 30 }, 'shhhhh');
// sign with RSA SHA256
var cert = fs.readFileSync('private.key'); // get private key
var token = jwt.sign({ foo: 'bar' }, cert, { algorithm: 'RS256'});
// sign asynchronously
jwt.sign({ foo: 'bar' }, cert, { algorithm: 'RS256' }, function(err, token) {
console.log(token);
});
`
#### Token Expiration (exp claim)
The standard for JWT defines an exp claim for expiration. The expiration is represented as a NumericDate:
> A JSON numeric value representing the number of seconds from 1970-01-01T00:00:00Z UTC until the specified UTC date/time, ignoring leap seconds. This is equivalent to the IEEE Std 1003.1, 2013 Edition [POSIX.1] definition "Seconds Since the Epoch", in which each day is accounted for by exactly 86400 seconds, other than that non-integer values can be represented. See RFC 3339 [RFC3339] for details regarding date/times in general and UTC in particular.
This means that the exp field should contain the number of seconds since the epoch.
Signing a token with 1 hour of expiration:
`javascript
jwt.sign({
exp: Math.floor(Date.now() / 1000) + (60 * 60),
data: 'foobar'
}, 'secret');
`
Another way to generate a token like this with this library is:
`javascript
jwt.sign({
data: 'foobar'
}, 'secret', { expiresIn: 60 * 60 });
//or even better:
jwt.sign({
data: 'foobar'
}, 'secret', { expiresIn: '1h' });
`
$3
(Asynchronous) If a callback is supplied, function acts asynchronously. Callback is passed the decoded payload if the signature and optional expiration, audience, or 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
* algorithms: List of strings with the names of the allowed algorithms. For instance, ["HS256", "HS384"].
* audience: if you want to check audience (aud), provide a value here
* issuer (optional): string or array of strings of valid values for the iss field.
* ignoreExpiration: if true do not validate the expiration of the token.
* ignoreNotBefore...
* subject: if you want to check subject (sub), provide a value here
* clockTolerance: number of seconds to tolerate when checking the nbf and exp claims, to deal with small clock differences among different servers
* maxAge: the maximum allowed age for tokens to still be valid. Currently it is expressed in milliseconds or a string describing a time span zeit/ms. Eg: 1000, "2 days", "10h", "7d". We advise against using milliseconds precision, though, since JWTs can only contain seconds. The maximum precision might be reduced to seconds in the future.
* clockTimestamp: the time in seconds that should be used as the current time for all necessary comparisons (also against maxAge, so our advise is to avoid using clockTimestamp and a maxAge in milliseconds together)
`js
// 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
});
// verify jwt id
var cert = fs.readFileSync('public.pem'); // get public key
jwt.verify(token, cert, { audience: 'urn:foo', issuer: 'urn:issuer', jwtid: 'jwtid' }, function(err, decoded) {
// if jwt id mismatch, err == invalid jwt id
});
// verify subject
var cert = fs.readFileSync('public.pem'); // get public key
jwt.verify(token, cert, { audience: 'urn:foo', issuer: 'urn:issuer', jwtid: 'jwtid', subject: 'subject' }, function(err, decoded) {
// if subject mismatch, err == invalid subject
});
// alg mismatch
var cert = fs.readFileSync('public.pem'); // get public key
jwt.verify(token, cert, { algorithms: ['RS256'] }, function (err, payload) {
// if token alg != RS256, err == invalid signature
});
`
$3
(Synchronous) Returns the decoded payload without verifying if the signature is valid.
__Warning:__ This will __not__ verify whether the signature is valid. You should __not__ use this for untrusted messages. You most likely want to use jwt.verify instead.
token is the JsonWebToken string
options:
* json: force JSON.parse on the payload even if the header doesn't contain "typ":"JWT".
* complete: return an object with the decoded payload and header.
Example
`js
// get the decoded payload ignoring signature, no secretOrPrivateKey needed
var decoded = jwt.decode(token);
// get the decoded payload and header
var decoded = jwt.decode(token, {complete: true});
console.log(decoded.header);
console.log(decoded.payload)
`
Errors & Codes
Possible thrown errors during verification.
Error is the first argument of the verification callback.
$3
Thrown error if the token is expired.
Error object:
* name: 'TokenExpiredError'
* message: 'jwt expired'
* expiredAt: [ExpDate]
`js
jwt.verify(token, 'shhhhh', function(err, decoded) {
if (err) {
/*
err = {
name: 'TokenExpiredError',
message: 'jwt expired',
expiredAt: 1408621000
}
*/
}
});
`
$3
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 id invalid. expected: [OPTIONS JWT ID]'
* 'jwt subject invalid. expected: [OPTIONS SUBJECT]'
`js
jwt.verify(token, 'shhhhh', function(err, decoded) {
if (err) {
/*
err = {
name: 'JsonWebTokenError',
message: 'jwt malformed'
}
*/
}
});
``