Mojo::JWT(3)

NAME
Mojo::JWT - JSON Web Token the Mojo way

SYNOPSIS
  my $jwt = Mojo::JWT->new(claims => {...}, secret => 's3cr3t')->encode;
  my $claims = Mojo::JWT->new(secret => 's3cr3t')->decode($jwt);

DESCRIPTION
JSON Web Token is described in <https://tools.ietf.org/html/rfc7519>. Mojo::JWT implements that standard with an API that should feel familiar to Mojolicious users (though of course it is useful elsewhere). Indeed, JWT is much like Mojolicious::Sessions except that the result is a url-safe text string rather than a cookie.

In JWT, the primary payload is called the "claims", and a few claims are reserved, as seen in the IETF document. The header and the claims are signed when stringified to guard against tampering. Note that while signed, the data is not encrypted, so don't use it to send secrets over clear channels.

ATTRIBUTES
Mojo::JWT inherits all of the attributes from Mojo::Base and implements the following new ones.

  algorithm
The algorithm to be used to sign a JWT during encoding or else the algorithm that was used for the most recent decoding. Defaults to "HS256" until a decode is performed.

"none" is an acceptable encoding algorithm, however for it to be used to decode, "allow_none" must be set.

  allow_none
To prevent spoofing attacks, "allow_none" must be explicitly set to a true value otherwise decoding a JWT which specifies the "none" algorithm will result in an exception. The default is of course false.

  claims
The payload to be encoded or else the claims from the most recent decoding. This must be a hash reference, array references are not allowed as the top-level JWT claims.

  expires
The epoch time value after which the JWT value should not be considered valid. This value (if set and not undefined) will be used as the "exp" key in the claims or was extracted from the claims during the most recent decoding.

  header
You may set your own headers when encoding the JWT bypassing a hash reference to the "header" attribute. Please note that there are two default headers set. alg is set to the value of "algorithm" or 'HS256' and typ is set to 'JWT'. These cannot be overridden.

  not_before
The epoch time value before which the JWT value should not be considered valid. This value (if set and not undefined) will be used as the "nbf" key in the claims or was extracted from the claims during the most recent decoding.

  public
The public key to be used in decoding an asymmetrically signed JWT (eg. RSA).

  secret
The symmetric secret (eg. HMAC) or else the private key used in encoding an asymmetrically signed JWT (eg. RSA).

  set_iat
If true (false by default), then the "iat" claim will be set to the value of "now" during "encode".

  jwks
An arrayref of JWK objects used by "decode" to verify the input token when matching with the JWTs "kid" field.

    my $jwks = Mojo::UserAgent->new->get('https://example.com/oidc/jwks.json')->result->json('/keys');
    my $jwt = Mojo::JWT->new(jwks => $jwks);
    $jwk->decode($token);

METHODS
Mojo::JWT inherits all of the methods from Mojo::Base and implements the following new ones.

  add_jwkset
    my $jwkset = Mojo::UserAgent->new->get('https://example.com/oidc/jwks.json')->result->json;
    my $jwt = Mojo::JWT->new->add_jwkset($jwksset);
    $jwk->decode($token);

Helper for appending a jwkset to the "jwks". Accepts a hashref with a "keys" field that is an arrayref of jwks and also an arrayref directly. Appends the JWKs to "jwks". Returns the instance.

  decode
  my $claims = $jwt->decode($token);

  my $peek = sub { my ($jwt, $claims) = @_; ... };
  my $claims = $jwt->decode($token, $peek);

Decode and parse a JSON Web Token string and return the claims hashref. Calling this function immediately sets the "token" to the passed in token. It also sets "algorithm" to "undef" and unsets "claims", "expires" and "not_before". These values are then set as part of the parsing process.

Parsing occurs as follows

•   The "algorithm" is extracted from the header and set, if not present or permissible an exception is thrown

•   Any JWKs in "/jwks" are checked against the headers and if one is found then it is set in "public" or "secret" as appropriate to the "algorithm"

•   If a $peek callback is provided, it is called with the instance and claims as arguments

•   The signature is verified or an exception is thrown

•   The timing claims ("expires" and "not_before"), if present, are evaluated, failures result in exceptions. On success the values are set in the relevant attributes

•   The "claims" attribute is set and the claims are returned.

Note that when the $peek callback is invoked, the claims have not yet been verified. This callback is most likely to be used to inspect the "iss" or issuer claim to determine a secret or key for decoding. The return value is ignored, changes should be made to the instances attributes directly. Since the "algorithm" has already been parsed, it is available via the instance attribute as well.

  encode
  my $token = $jwt->encode;

Encode the data expressed in the instance attributes: "algorithm", "claims", "expires", "not_before". Note that if the timing attributes are given, they override existing keys in the "claims". Calling "encode" immediately clears the "token" and upon completion sets it to the result as well as returning it.

Note also that due to Perl's hash randomization, repeated encoding is not guaranteed to result in the same encoded string. However any encoded string will survive an encode/decode roundtrip.

  header
  my $header = $jwt->header;

Returns a hash reference representing the JWT header, constructed from instance attributes (see "algorithm").

  now
  my $time = $jwt->now;

Returns the current time, currently implemented as the core "time" function.

  sign_hmac
  my $signature = $jwt->sign_hmac($size, $payload);

Returns the HMAC SHA signature for the given size and payload. The "secret" attribute is used as the symmetric key. The result is not yet base64 encoded. This method is provided mostly for the purposes of subclassing.

  sign_rsa
  my $signature = $jwt->sign_rsa($size, $payload);

Returns the RSA signature for the given size and payload. The "secret" attribute is used as the private key. The result is not yet base64 encoded. This method is provided mostly for the purposes of subclassing.

  token
The most recently encoded or decoded token. Note that any attribute modifications are not taken into account until "encode" is called again.

  verify_rsa
  my $bool = $jwt->verify_rsa($size, $payload, $signature);

Returns true if the given RSA size algorithm validates the given payload and signature. The "public" attribute is used as the public key. This method is provided mostly for the purposes of subclassing.

SEE ALSO

Acme::JWT
JSON::WebToken
<http://jwt.io/>

SOURCE REPOSITORY
<http://github.com/jberger/Mojo-JWT>

AUTHOR
Joel Berger, <joel.a.berger@gmail.com>

CONTRIBUTORS
Christopher Raa (mishanti1)

Cameron Daniel (ccakes)

COPYRIGHT AND LICENSE
Copyright (C) 2015 by "AUTHOR" and "CONTRIBTORS".

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.