Method prepare_key

jwt/algorithms.py:444–475

(self, key: AllowedRSAKeys | str | bytes)

            return None

        def prepare_key(self, key: AllowedRSAKeys | str | bytes) -> AllowedRSAKeys:
            if isinstance(key, self._crypto_key_types):
                # Cast is required for type narrowing on Python 3.9's mypy
                # but redundant on newer mypy versions; suppress both
                # diagnostics so the line works across all supported envs.
                return cast(AllowedRSAKeys, key)  # type: ignore[redundant-cast,unused-ignore]

            if not isinstance(key, (bytes, str)):
                raise TypeError("Expecting a PEM-formatted key.")

            key_bytes = force_bytes(key)

            try:
                if key_bytes.startswith(b"ssh-rsa"):
                    public_key: PublicKeyTypes = load_ssh_public_key(key_bytes)
                    self.check_crypto_key_type(public_key)
                    return cast(RSAPublicKey, public_key)
                else:
                    private_key: PrivateKeyTypes = load_pem_private_key(
                        key_bytes, password=None
                    )
                    self.check_crypto_key_type(private_key)
                    return cast(RSAPrivateKey, private_key)
            except ValueError:
                try:
                    public_key = load_pem_public_key(key_bytes)
                    self.check_crypto_key_type(public_key)
                    return cast(RSAPublicKey, public_key)
                except (ValueError, UnsupportedAlgorithm):
                    raise InvalidKeyError(
                        "Could not parse the provided public key."
                    ) from None

        @overload
        @staticmethod