PyJWT [![Build Status](https://travis-ci.org/progrium/pyjwt.png?branch=master)](https://travis-ci.org/progrium/pyjwt)
=====
A Python implementation of [JSON Web Token draft 01](http://self-issued.info/docs/draft-jones-json-web-token-01.html).

Installing
----------

    sudo easy_install PyJWT

**Note**: The RSASSA-PKCS1-v1_5 algorithms depend on PyCrypto. If you plan on
using any of those algorithms you'll need to install it as well.

    sudo easy_install PyCrypto

Usage
-----

    import jwt
    jwt.encode({"some": "payload"}, "secret")

Additional headers may also be specified.

    jwt.encode({"some": "payload"}, "secret", headers={"kid": "230498151c214b788dd97f22b85410a5"})

Note the resulting JWT will not be encrypted, but verifiable with a secret key.

    jwt.decode("someJWTstring", "secret")

If the secret is wrong, it will raise a `jwt.DecodeError` telling you as such.
You can still get the payload by setting the `verify` argument to `False`.

    jwt.decode("someJWTstring", verify=False)

Algorithms
----------

The JWT spec supports several algorithms for cryptographic signing. This library
currently supports:

* HS256 - HMAC using SHA-256 hash algorithm (default)
* HS384 - HMAC using SHA-384 hash algorithm
* HS512 - HMAC using SHA-512 hash algorithm
* RS256 - RSASSA-PKCS1-v1_5 signature algorithm using SHA-256 hash algorithm
* RS384 - RSASSA-PKCS1-v1_5 signature algorithm using SHA-384 hash algorithm
* RS512 - RSASSA-PKCS1-v1_5 signature algorithm using SHA-512 hash algorithm

Change the algorithm with by setting it in encode:

    jwt.encode({"some": "payload"}, "secret", "HS512")

When using the RSASSA-PKCS1-v1_5 algorithms, the `key` argument in both
`jwt.encode()` and `jwt.decode()` (`"secret"` in the examples) is expected to
be an RSA private key as imported with `Crypto.PublicKey.RSA.importKey()`.

Tests
-----

You can run tests from the project root after cloning with:

    python tests/test_jwt.py

Support of reserved claim names
-------------------------------

JSON Web Token defines some reserved claim names and defines how they should be
used. PyJWT supports these reserved claim names:

 - "exp" (Expiration Time) Claim

Expiration Time Claim
=====================

From [draft 01 of the JWT spec](http://self-issued.info/docs/draft-jones-json-web-token-01.html#ReservedClaimName):

> The exp (expiration time) claim identifies the expiration time on or after
> which the JWT MUST NOT be accepted for processing. The processing of the exp
> claim requires that the current date/time MUST be before the expiration
> date/time listed in the exp claim. Implementers MAY provide for some small
> leeway, usually no more than a few minutes, to account for clock skew. Its
> value MUST be a number containing an IntDate value. Use of this claim is
> OPTIONAL.

You can pass the expiration time as a UTC UNIX timestamp (an int) or as a
datetime, which will be converted into an int. For example:

    jwt.encode({"exp": 1371720939}, "secret")

    jwt.encode({"exp": datetime.utcnow()}, "secret")

Expiration time is automatically verified in `jwt.decode()` and raises
`jwt.ExpiredSignature` if the expiration time is in the past:

    import jwt
    try:
        jwt.decode('JWT_STRING', "secret")
    except jwt.ExpiredSignature:
        # Signature has expired

Expiration time will be compared to the current UTC time (as given by
`timegm(datetime.utcnow().utctimetuple())`), so be sure to use a UTC timestamp
or datetime in encoding.

You can turn off expiration time verification with the `verify_expiration` argument.

PyJWT also supports the leeway part of the expiration time definition, which
means you can validate a expiration time which is in the past but not very far.
For example, if you have a JWT payload with a expiration time set to 30 seconds
after creation but you know that sometimes you will process it after 30 seconds,
you can set a leeway of 10 seconds in order to have some margin:

    import jwt, time
    jwt_payload = jwt.encode({'exp': datetime.utcnow() + datetime.timedelta(seconds=30)}, 'secret')
    time.sleep(32)
    # Jwt payload is now expired
    # But with some leeway, it will still validate
    jwt.decode(jwt_payload, 'secret', leeway=10)


License
-------

MIT