import json
import urllib.request
from functools import lru_cache
from typing import Any, List
from .api_jwk import PyJWK, PyJWKSet
from .api_jwt import decode_complete as decode_token
from .exceptions import PyJWKClientError
class PyJWKClient:
def __init__(self, uri: str, cache_keys: bool = True, max_cached_keys: int = 16):
self.uri = uri
if cache_keys:
# Cache signing keys
# Ignore mypy (https://github.com/python/mypy/issues/2427)
self.get_signing_key = lru_cache(maxsize=max_cached_keys)(self.get_signing_key) # type: ignore
def fetch_data(self) -> Any:
with urllib.request.urlopen(self.uri) as response:
return json.load(response)
def get_jwk_set(self) -> PyJWKSet:
data = self.fetch_data()
return PyJWKSet.from_dict(data)
def get_signing_keys(self) -> List[PyJWK]:
jwk_set = self.get_jwk_set()
signing_keys = []
for jwk_set_key in jwk_set.keys:
if jwk_set_key.public_key_use == "sig" and jwk_set_key.key_id:
signing_keys.append(jwk_set_key)
if len(signing_keys) == 0:
raise PyJWKClientError("The JWKS endpoint did not contain any signing keys")
return signing_keys
def get_signing_key(self, kid: str) -> PyJWK:
signing_keys = self.get_signing_keys()
signing_key = None
for key in signing_keys:
if key.key_id == kid:
signing_key = key
break
if not signing_key:
raise PyJWKClientError(
f'Unable to find a signing key that matches: "{kid}"'
)
return signing_key
def get_signing_key_from_jwt(self, token: str) -> PyJWK:
unverified = decode_token(token, options={"verify_signature": False})
header = unverified["header"]
return self.get_signing_key(header.get("kid"))
