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Super simple JSON Web Tokens with Python

Project description

EasyJWT

PyPI PyPI - License Build Status codecov Documentation Status PyPI - Python Version

EasyJWT provides a simple interface to creating and verifying JSON Web Tokens (JWTs) in Python. It allows you to once define the claims of the JWT, and to then create and accept tokens with these claims without having to check if all the required data is given or if the token actually is the one you expect.

from easyjwt import EasyJWT

# Define the claims of your token.
class MySuperSimpleJWT(EasyJWT):

    def __init__(self, key):
        super().__init__(key)

        # Define a claim `name`.
        self.name = None

# Create a token with some values.
token_object = MySuperSimpleJWT('Super secret key')
token_object.name = 'Zaphod Beeblebrox'
token = token_object.create()

# Verify the created token.
verified_token_object = MySuperSimpleJWT.verify(token, 'Super secret key')
assert verified_token_object.name == 'Zaphod Beeblebrox'

Features

  • Define the claims of your token once as a class, then use this class to easily create and verify multiple tokens.
  • No worries about typos in dictionary keys: the definition of your claim set as a class enables IDEs to find those typos for you.
  • Multiple tokens may have the same claims, but different intentions. EasyJWT will take care of this for you: you can define a token for account validation and one for account deletion, both with the account ID as a claim, and you don't need to worry about accidentally deleting a newly created account instead of validating it, just because someone mixed up the tokens.
  • Tokens will be rejected if mandatory claims are missing or unexpected claims are included.
  • You can define optional claims for your tokens.
  • All registered JWT claims are supported: aud, exp, iat, iss, jti, nbf, and sub.

System Requirements & Installation

EasyJWT requires Python 3.6 or newer.

EasyJWT is available on PyPI. You can install it using your favorite package manager.

  • PIP:

    python -m pip install easyjwt
    
  • Pipenv:

    pipenv install easyjwt
    

Usage

Before you can create tokens, you need to define the claims that your token will have. You do this by creating a token class that inherits from EasyJWT. In its __init__ method, you specify the claims of your token, simply by defining attributes with the name of your claims. EasyJWT will consider all attributes to be claims, unless they start with an underscore _. Remember to call the __init__ method on the parent class to correctly initialize the objects of your class.

from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    def __init__(self, key):
        super().__init__(key)

        # These are the claims of your token: `name` and `email`.
        self.name = None
        self.email = None

        # This attribute will not become a claim since it starts with an underscore.
        self._not_an_attribute = True

You can now create the actual token by instantiating your class with the key with which the token will be encoded, setting your values on this token object, and then calling EasyJWT's create method.

token_object = MySuperSimpleJWT('Super secret key')
token_object.name = 'Zaphod Beeblebrox'
token_object.email = 'elprez@universe.gov'

token = token_object.create()

If you forget to set the value of one your claims, the creation will fail with an MissingRequiredClaimsError exception (see below for information on how to define optional claims).

Once you receive a token to verify, you simply pass it and the key with which it has been encoded to EasyJWT's verify method. If the token is valid, the returned object will contain the values of the token.

verified_token_object = MySuperSimpleJWT.verify(token, 'Super secret key')

assert verified_token_object.name == 'Zaphod Beeblebrox'
assert verified_token_object.email == 'elprez@universe.gov'

If you try to verify a token that is missing one or more of the claims specified in your token class, or it includes one or more claims that you did not specify in your token class, the verification will fail by raising an InvalidClaimSetError exception. Thus, you always know that the data you expect in the token will in fact be present.

The neat thing about EasyJWT is: it knows with which class a token has been created, and will only accept tokens if they have been created with the class with which you are trying to verify it (see below for more information and how to disable this behavior). Thus, you can have multiple token classes with the same claims, but different contexts, and you don't have to worry about mixing up their tokens!

from easyjwt import EasyJWT

class AccountValidationToken(EasyJWT):
    """ Validate the newly created user account with the specified ID. """

    def __init__(self, key):
        super().__init__(key)

        self.user_id = None

class AccountDeletionToken(EasyJWT):
    """ Delete the user account with the specified ID. """

    def __init__(self, key):
        super().__init__(key)

        self.user_id = None

validation_token_object = AccountValidationToken('Super secret key')
validation_token_object.user_id = 42
validation_token = validation_token_object.create()

# Verifying the validation token with the deletion token class will fail!
# AccountDeletionToken.verify(validation_token, 'Super secret key')

If you try to verify a token with a wrong class, EasyJWT will automatically reject your token by raising an InvalidClassError exception.

Accepting Third-Party Tokens

By default, EasyJWT will only accept tokens that have been created by the class with which you verify it.[1] This is done by including a special claim in the token upon creation. This claim is required when verifying a token. Tokens without this claim or with a wrong value for this claim will fail verification. Usually, tokens from other sources will not include this claim, and thus the validation of such a token will fail.

You can disable the verification of this special claim by setting a special flag in your token class. This flag will also prevent the special claim from being included in the created tokens.

from easyjwt import EasyJWT

class ThirdPartyJWT(EasyJWT):

    # Disable the validation of the special claim.
    strict_verification = False

    # The usual definition of the token's claim set ...

If you try to verify a token without this special claim and without disabling the strict verification mode, EasyJWT will raise an UnspecifiedClassError exception.


[1]: To be precise, the name of the class with which the token has been created must be the same as the name of the class with which it is being verified. This class name is included in each token created by EasyJWT in the special claim _easyjwt_class.

Encoding Algorithms

Tokens created by EasyJWT are encoded using the HS256 algorithm by default. If you want to use a different algorithm, you can specify this algorithm in the definition of your token class.

from easyjwt import Algorithm
from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    # Use the HS512 algorithm.
    algorithm = Algorithm.HS512

    # The usual definition of the token's claim set ...

If you have previously created tokens with your token class, and later want to change the algorithm for new tokens, you should tell EasyJWT to still use the previous algorithms for decoding tokens. Otherwise, tokens created with the old version of your code cannot be verified!

from easyjwt import Algorithm
from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    # Use the HS512 algorithm.
    algorithm = Algorithm.HS512

    # Previously, tokens have been encoded with HS256, EasyJWT's default algorithm.
    # Thus, list it here.
    previous_algorithms = {Algorithm.HS256}

    # The usual definition of the token's claim set ...

You can find a list of all available algorithms in the API documentation.

Optional Claims

All the claims you specify in the __init__ method of your token class are mandatory, both for creating a token of this class and for verifying a token. If you want some of these claims to be optional (both for creating and verifying a token), you can override EasyJWT's _optional_claims class variable. You can override this class variable in your token class to include the names of your optional claims. Note that you must include the value of EasyJWT._optional_claims in your class. Otherwise, the registered claims will become mandatory.

from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    # The claim `my_optional_claim` is optional. All other claims are still mandatory.
    _optional_claims = EasyJWT._optional_claims.union({'my_optional_claim'})

    def __init__(self, key):
        super().__init__(key)

        self.my_optional_claim = None
        self.my_mandatory_claim = None

token_object = MySuperSimpleJWT('Super secret key')
token_object.my_mandatory_claim = 'Some value'

token = token_object.create()

Registered Claims

EasyJWT supports all registered claims of the JWT specification: aud, exp, iat, iss, jti, nbf, and sub. All of these claims are optional.

Audience: aud

The audience identifies the recipients of the token, and can either be a string or a list of strings.

You can set an audience for your token using the attribute audience of your token object. This attribute will automatically be mapped to the aud claim when creating the token.

from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    def __init__(self, key):
        super().__init__(key)

        self.name = None

token_object = MySuperSimpleJWT('Super secret key')
token_object.name = 'Zaphod Beeblebrox'

# This token is intended for everyone, and especially for Zaphod Beeblebrox.
token_object.audience = ['Zaphod Beeblebrox', 'Everyone']

token = token_object.create()

To verify a token with an audience, you must pass at least one of the audience values to EasyJWT's verify method. Otherwise, the verification will fail with an InvalidAudienceError exception. After the verification, the token's audience will be set on the audience attribute.

# We are everyone, so this token is intended for us.
verified_token_object = MySuperSimpleJWT.verify(token, 'Super secret key', audience='Everyone')

assert verified_token_object.audience == ['Zaphod Beeblebrox', 'Everyone']

Expiration Date: exp

The expiration date specifies how long the token will be valid. If a token with an expiration date is verified after its expiration date has passed, the token will be invalid.

You can set an expiration date for your token using the attribute expiration_date to a datetime object. This attribute will automatically be mapped to the exp claim when creating the token. Note that you must specify the expiration date in UTC.

import datetime
from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    def __init__(self, key):
        super().__init__(key)

        self.name = None

token_object = MySuperSimpleJWT('Super secret key')
token_object.name = 'Zaphod Beeblebrox'

# This token will expire in 15 minutes.
token_object.expiration_date = datetime.datetime.utcnow() + datetime.timedelta(minutes=15)

token = token_object.create()

When verifying a token with an expiration date, EasyJWT automatically checks if the expiration date has passed. If this is the case, the verification will fail with an ExpiredTokenError exception. After the verification, the token's expiration date will be set on the expiration_date attribute as a datetime object in UTC.

Issued At: iat

The issued at-date specifies the token's time of creation.

When creating a token, this claim will automatically be set to the current time. If you want to set a different issued at-date, you can pass a datetime object (in UTC) to the optional issued_at parameter of EasyJWT's create method.

import datetime
from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    def __init__(self, key):
        super().__init__(key)

        self.name = None

token_object = MySuperSimpleJWT('Super secret key')
token_object.name = 'Zaphod Beeblebrox'

# This token was issued five minutes ago.
token = token_object.create(issued_at=datetime.datetime.utcnow() - datetime.timedelta(minutes=5))

After verifying a token with an issued at-date, its issued at-date will be set on the issued_at_date attribute.

Issuer: iss

The issuer identifies the creator of the token.

You can set the issuer of your token using the issuer attribute of your token object. This attribute will automatically be mapped to the iss claim when creating the token.

from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    def __init__(self, key):
        super().__init__(key)

        self.name = None

token_object = MySuperSimpleJWT('Super secret key')
token_object.name = 'Zaphod Beeblebrox'

# This token is intended for everyone, and especially for Zaphod Beeblebrox.
token_object.issuer = 'Arthur Dent'

token = token_object.create()

To verify a token with an issuer, you must pass the issuer specified in the token to EasyJWT's verify method. Otherwise, the verification will fail with an InvalidIssuerError exception. After the verification, the token's issuer will be set on the issuer attribute.

# We are everyone, so this token is intended for us.
verified_token_object = MySuperSimpleJWT.verify(token, 'Super secret key', issuer='Arthur Dent')

assert verified_token_object.issuer == 'Arthur Dent'

JWT ID: jti

The JWT ID is an identifier for your token. It must be unique for each token.

You can set the JWT ID of your token using the JWT_ID attribute of your token object. This attribute will automatically be mapped to the jti claim when creating the token

from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    def __init__(self, key):
        super().__init__(key)

        self.name = None

token_object = MySuperSimpleJWT('Super secret key')
token_object.name = 'Zaphod Beeblebrox'

# This ID must be unique for each token.
token_object.JWT_ID = 'My super simple JWT 1'

token = token_object.create()

After verifying a token with a JWT ID, this ID will be set on the JWT_ID attribute.

Note that this claim is not verified by EasyJWT. It is your responsibility to validate it after verifying the token if you need this validation.

Not Before: nbf

The not before-date specifies the time before which the token will not be valid. If a token with a not before-date is verified before its not before-date has been reached, the token will be invalid.

You can set a not before-date for your token using the attribute not_before_date to a datetime object. This attribute will automatically be mapped to the nbf claim when creating the token. Note that you must specify the not before-date in UTC.

import datetime
from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    def __init__(self, key):
        super().__init__(key)

        self.name = None

token_object = MySuperSimpleJWT('Super secret key')
token_object.name = 'Zaphod Beeblebrox'

# This token will be valid in 5 minutes.
token_object.not_before_date = datetime.datetime.utcnow() + datetime.timedelta(minutes=5)

token = token_object.create()

When verifying a token with a not before-date, EasyJWT automatically checks if the not before-date has been reached. If this is not the case, the verification will fail with an ImmatureTokenError exception. After the verification, the token's not before-date will be set on the not_before_date attribute as a datetime object in UTC.

Subject: sub

The subject specifies the topic of your token.

You can set the subject of your token using the subject attribute of your token object. This attribute will automatically be mapped to the sub claim when creating the token.

from easyjwt import EasyJWT

class MySuperSimpleJWT(EasyJWT):

    def __init__(self, key):
        super().__init__(key)

        self.name = None

token_object = MySuperSimpleJWT('Super secret key')
token_object.name = 'Zaphod Beeblebrox'

# This token is all about Douglas Adams' master work.
token_object.subject = 'The Hitchhiker\'s Guide to the Galaxy'

token = token_object.create()

After verifying a token with a subject, this subject will be set on the subject attribute.

Note that this claim is not verified by EasyJWT. It is your responsibility to validate it after verifying the token if you need this validation.

Future Ideas

  • Allow creating tokens without an issued at-date.
  • Add a mode to accept arbitrary claims and create corresponding attributes as needed.
  • Allow specifying functions to pack and unpack claim values before creating a token and after verifying a token, respectively.

Acknowledgements

EasyJWT is just an easy-to-use abstraction layer around José Padilla's PyJWT library that does the actual work of creating and verifying the tokens according to the JWT specification. Without his work, EasyJWT would not be possible.

License

EasyJWT is developed by Bastian Meyer <bastian@bastianmeyer.eu> and is licensed under the MIT License. For details, see the attached LICENSE file.

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