api_jwk.py

import json
from datetime import datetime, timezone

from .algorithms import get_default_algorithms
from .exceptions import InvalidKeyError, PyJWKError, PyJWKSetError


class PyJWK:
    def __init__(self, jwk_data, algorithm=None):
        self._algorithms = get_default_algorithms()
        self._jwk_data = jwk_data

        kty = self._jwk_data.get("kty", None)
        if not kty:
            raise InvalidKeyError(f"kty is not found: {self._jwk_data}")

        if not algorithm and isinstance(self._jwk_data, dict):
            algorithm = self._jwk_data.get("alg", None)

        if not algorithm:
            # Determine alg with kty (and crv).
            crv = self._jwk_data.get("crv", None)
            if kty == "EC":
                if crv == "P-256" or not crv:
                    algorithm = "ES256"
                elif crv == "P-384":
                    algorithm = "ES384"
                elif crv == "P-521":
                    algorithm = "ES512"
                elif crv == "secp256k1":
                    algorithm = "ES256K"
                else:
                    raise InvalidKeyError(f"Unsupported crv: {crv}")
            elif kty == "RSA":
                algorithm = "RS256"
            elif kty == "oct":
                algorithm = "HS256"
            elif kty == "OKP":
                if not crv:
                    raise InvalidKeyError(f"crv is not found: {self._jwk_data}")
                if crv == "Ed25519":
                    algorithm = "EdDSA"
                else:
                    raise InvalidKeyError(f"Unsupported crv: {crv}")
            else:
                raise InvalidKeyError(f"Unsupported kty: {kty}")

        self.Algorithm = self._algorithms.get(algorithm)

        if not self.Algorithm:
            raise PyJWKError(f"Unable to find a algorithm for key: {self._jwk_data}")

        self.key = self.Algorithm.from_jwk(self._jwk_data)

    @staticmethod
    def from_dict(obj, algorithm=None):
        return PyJWK(obj, algorithm)

    @staticmethod
    def from_json(data, algorithm=None):
        obj = json.loads(data)
        return PyJWK.from_dict(obj, algorithm)

    @property
    def key_type(self):
        return self._jwk_data.get("kty", None)

    @property
    def key_id(self):
        return self._jwk_data.get("kid", None)

    @property
    def public_key_use(self):
        return self._jwk_data.get("use", None)


class PyJWKSet:
    def __init__(self, keys):
        self.keys = []

        if not keys or not isinstance(keys, list):
            raise PyJWKSetError("Invalid JWK Set value")

        if len(keys) == 0:
            raise PyJWKSetError("The JWK Set did not contain any keys")

        for key in keys:
            try:
                self.keys.append(PyJWK(key))
            except PyJWKError:
                # skip unusable keys
                continue

        if len(self.keys) == 0:
            raise PyJWKSetError("The JWK Set did not contain any usable keys")

    @staticmethod
    def from_dict(obj):
        keys = obj.get("keys", [])
        return PyJWKSet(keys)

    @staticmethod
    def from_json(data):
        obj = json.loads(data)
        return PyJWKSet.from_dict(obj)

    def __getitem__(self, kid):
        for key in self.keys:
            if key.key_id == kid:
                return key
        raise KeyError(f"keyset has no key for kid: {kid}")


class PyJWTSetWithTimestamp:
    def __init__(self, jwt_set: PyJWKSet, timestamp: datetime = None):
        self.jwt_set = jwt_set

        if timestamp is None:
            self.timestamp = datetime.now(timezone.utc)
        else:
            self.timestamp = timestamp

    def get_jwk_set(self):
        return self.jwt_set

    def get_timestamp(self):
        return self.timestamp