JWT/Usage

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jwt.sign(payload, secretOrPrivateKey, [options, callback])

(Asynchronous) If a callback is supplied, the callback is called with the err or the JWT.

(Synchronous) Returns the JsonWebToken as string

payload could be an object literal, buffer or string representing valid JSON.

Please note that exp or any other claim is only set if the payload is an object literal. Buffer or string payloads are not checked for JSON validity.

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

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". A numeric value is interpreted as a seconds count. If you use a string be sure you provide the time units (days, hours, etc), otherwise milliseconds unit is used by default ("120" is equal to "120ms").

  • notBefore: expressed in seconds or a string describing a time span zeit/ms.

Eg: 60, "2 days", "10h", "7d". A numeric value is interpreted as a seconds count. If you use a string be sure you provide the time units (days, hours, etc), otherwise milliseconds unit is used by default ("120" is equal to "120ms").

  • audience
  • issuer
  • jwtid
  • subject
  • noTimestamp
  • header
  • keyid
  • mutatePayload: if true, the sign function will modify the payload object directly. This is useful if you need a raw reference to the payload after claims have been applied to it but before it has been encoded into a token.

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.

  • exp : expiresIn
  • nbf : notBefore
  • iat : issuedAt

Remember that exp, nbf and iat are NumericDate, see related Token Expiration (exp claim)

The header can be customized via the options.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.

Synchronous Sign with default (HMAC SHA256)

var jwt = require('jsonwebtoken');
var token = jwt.sign({ foo: 'bar' }, 'shhhhh');

Synchronous Sign with RSA SHA256

// sign with RSA SHA256

var privateKey = fs.readFileSync('private.key');
var token = jwt.sign({ foo: 'bar' }, privateKey, { algorithm: 'RS256'});

Sign asynchronously

jwt.sign({ foo: 'bar' }, privateKey, { algorithm: 'RS256' }, function(err, token) {
 console.log(token);
});

Backdate a jwt 30 seconds

var older_token = jwt.sign({ foo: 'bar', iat: Math.floor(Date.now() / 1000) - 30 }, 'shhhhh');

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:

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:

jwt.sign({
  data: 'foobar'
}, 'secret', { expiresIn: 60 * 60 });

//or even better:

jwt.sign({
  data: 'foobar'
}, 'secret', { expiresIn: '1h' });

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

(Asynchronous) If a callback is supplied, function acts asynchronously.

The callback is called with the decoded payload if the signature is valid and optional expiration, audience, or issuer are valid. If not, it will be called with the error.

(Synchronous) If a callback is not supplied, function acts synchronously. Returns the payload decoded if the signature is valid and optional expiration, audience, or 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.

If jwt.verify is called asynchronous, secretOrPublicKey can be a function that should fetch the secret or public key.

jwt.decode(token [, options])

(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

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

(Asynchronous) If a callback is supplied, function acts asynchronously.

The callback is called with the decoded payload if the signature is valid and optional expiration, audience, or issuer are valid. If not, it will be called with the error.

(Synchronous) If a callback is not supplied, function acts synchronously. Returns the payload decoded if the signature is valid and optional expiration, audience, or 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.

If jwt.verify is called asynchronous, secretOrPublicKey can be a function that should fetch the secret or public key.

jwt.decode(token [, options])

(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

// 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)
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

// 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)