JSON Web Token (JWT) is structured by RFC7515: JSON Web Signature or RFC7516: JSON Web Encryption with certain payload claims. The JWT implementation in Authlib has all built-in algorithms via RFC7518: JSON Web Algorithms, it can also load private/public keys of RFC7517: JSON Web Key:
>>> from authlib.jose import jwt
>>> header = {'alg': 'RS256'}
>>> payload = {'iss': 'Authlib', 'sub': '123', ...}
>>> key = read_file('private.pem')
>>> s = jwt.encode(header, payload, key)
>>> claims = jwt.decode(s, read_file('public.pem'))
>>> print(claims)
{'iss': 'Authlib', 'sub': '123', ...}
>>> print(claims.header)
{'alg': 'RS256', 'typ': 'JWT'}
>>> claims.validate()
The imported jwt
is an instance of JsonWebToken
. It has all
supported JWS algorithms, and it can handle JWK automatically. When
JsonWebToken.encode()
a payload, JWT will check payload claims for
security, if you really want to expose them, you can always turn it off
via check=False
.
Important
JWT payload with JWS is not encrypted, it is just signed. Anyone can extract the payload without any private or public keys. Adding sensitive data like passwords, social security numbers in JWT payload is not safe if you are going to send them in a non-secure connection.
You can also use JWT with JWE which is encrypted. But this feature is not mature, documentation is not provided yet.
jwt.encode
is the method to create a JSON Web Token string. It encodes the
payload with the given alg
in header:
>>> from authlib.jose import jwt
>>> header = {'alg': 'RS256'}
>>> payload = {'iss': 'Authlib', 'sub': '123', ...}
>>> key = read_file('private.pem')
>>> s = jwt.encode(header, payload, key)
The available keys in headers are defined by RFC7515: JSON Web Signature.
jwt.decode
is the method to translate a JSON Web Token string into the
dict of the payload:
>>> from authlib.jose import jwt
>>> claims = jwt.decode(s, read_file('public.pem'))
The returned value is a JWTClaims
, check the next section to
validate claims value.
There are cases that we don’t want to support all the alg
values,
especially when decoding a token. In this case, we can pass a list
of supported alg
into JsonWebToken
:
>>> from authlib.jose import JsonWebToken
>>> jwt = JsonWebToken(['RS256'])
JsonWebToken.decode()
accepts 3 claims-related parameters: claims_cls
,
claims_option
and claims_params
. The default claims_cls
is
JWTClaims
. The decode
method returns:
>>> JWTClaims(payload, header, options=claims_options, params=claims_params)
Claims validation is actually handled by JWTClaims.validate()
, which
validates payload claims with claims_option
and claims_params
. For
standard JWTClaims, claims_params
value is not used, but it is used in
IDToken
.
Here is an example of claims_option
:
{
"iss": {
"essential": True,
"values": ["https://example.com", "https://example.org"]
},
"sub": {
"essential": True
"value": "248289761001"
},
"jti": {
"validate": validate_jti
}
}
It is a dict configuration, the option key is the name of a claim.