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Editing: jws.py
"""JSON Web Signature.""" import argparse import base64 import sys from typing import ( Any, Dict, FrozenSet, List, Mapping, Optional, Tuple, Type, cast, ) from cryptography import x509 from cryptography.hazmat.primitives.serialization import Encoding import josepy from josepy import b64, errors, json_util, jwa from josepy import jwk as jwk_mod class MediaType: """MediaType field encoder/decoder.""" PREFIX = "application/" """MIME Media Type and Content Type prefix.""" @classmethod def decode(cls, value: str) -> str: """Decoder.""" # 4.1.10 if "/" not in value: if ";" in value: raise errors.DeserializationError("Unexpected semi-colon") return cls.PREFIX + value return value @classmethod def encode(cls, value: str) -> str: """Encoder.""" # 4.1.10 if ";" not in value: assert value.startswith(cls.PREFIX) return value[len(cls.PREFIX) :] return value class Header(json_util.JSONObjectWithFields): """JOSE Header. .. warning:: This class supports **only** Registered Header Parameter Names (as defined in section 4.1 of the protocol). If you need Public Header Parameter Names (4.2) or Private Header Parameter Names (4.3), you must subclass and override :meth:`from_json` and :meth:`to_partial_json` appropriately. .. warning:: This class does not support any extensions through the "crit" (Critical) Header Parameter (4.1.11) and as a conforming implementation, :meth:`from_json` treats its occurrence as an error. Please subclass if you seek for a different behaviour. :ivar x5tS256: "x5t#S256" :ivar str typ: MIME Media Type, inc. :const:`MediaType.PREFIX`. :ivar str cty: Content-Type, inc. :const:`MediaType.PREFIX`. """ alg: Optional[jwa.JWASignature] = json_util.field( "alg", decoder=jwa.JWASignature.from_json, omitempty=True ) jku: Optional[bytes] = json_util.field("jku", omitempty=True) jwk: Optional[jwk_mod.JWK] = json_util.field( "jwk", decoder=jwk_mod.JWK.from_json, omitempty=True ) kid: Optional[str] = json_util.field("kid", omitempty=True) x5u: Optional[bytes] = json_util.field("x5u", omitempty=True) x5c: Tuple[x509.Certificate, ...] = json_util.field("x5c", omitempty=True, default=()) x5t: Optional[bytes] = json_util.field("x5t", decoder=json_util.decode_b64jose, omitempty=True) x5tS256: Optional[bytes] = json_util.field( "x5t#S256", decoder=json_util.decode_b64jose, omitempty=True ) typ: Optional[MediaType] = json_util.field( "typ", encoder=MediaType.encode, decoder=MediaType.decode, omitempty=True ) cty: Optional[MediaType] = json_util.field( "cty", encoder=MediaType.encode, decoder=MediaType.decode, omitempty=True ) crit: Tuple[Any, ...] = json_util.field("crit", omitempty=True, default=()) _fields: Dict[str, json_util.Field] def not_omitted(self) -> Dict[str, json_util.Field]: """Fields that would not be omitted in the JSON object.""" return { name: getattr(self, name) for name, field in self._fields.items() if not field.omit(getattr(self, name)) } def __add__(self, other: Any) -> "Header": if not isinstance(other, type(self)): raise TypeError("Header cannot be added to: {0}".format(type(other))) not_omitted_self = self.not_omitted() not_omitted_other = other.not_omitted() if set(not_omitted_self).intersection(not_omitted_other): raise TypeError("Addition of overlapping headers not defined") not_omitted_self.update(not_omitted_other) return type(self)(**not_omitted_self) def find_key(self) -> josepy.JWK: """Find key based on header. .. todo:: Supports only "jwk" header parameter lookup. :returns: (Public) key found in the header. :rtype: .JWK :raises josepy.errors.Error: if key could not be found """ if self.jwk is None: raise errors.Error("No key found") return self.jwk @crit.decoder # type: ignore def crit(unused_value: Any) -> Any: raise errors.DeserializationError('"crit" is not supported, please subclass') # x5c does NOT use JOSE Base64 (4.1.6) @x5c.encoder # type: ignore def x5c(value): """ .. versionchanged:: 2.0.0 The values are now `cryptography.x509.Certificate` objects. Previously these were `josepy.util.ComparableX509` objects, which wrapped `OpenSSL.crypto.X509` objects. """ return [base64.b64encode(cert.public_bytes(Encoding.DER)) for cert in value] @x5c.decoder # type: ignore def x5c(value): """ .. versionchanged:: 2.0.0 The values are now `cryptography.x509.Certificate` objects. Previously these were `josepy.util.ComparableX509` objects, which wrapped `OpenSSL.crypto.X509` objects. """ try: return tuple(x509.load_der_x509_certificate(base64.b64decode(cert)) for cert in value) except ValueError as error: raise errors.DeserializationError(error) class Signature(json_util.JSONObjectWithFields): """JWS Signature. :ivar combined: Combined Header (protected and unprotected, :class:`Header`). :ivar unicode protected: JWS protected header (Jose Base-64 decoded). :ivar header: JWS Unprotected Header (:class:`Header`). :ivar str signature: The signature. """ header_cls = Header combined: Header __slots__ = ("combined",) protected: str = json_util.field("protected", omitempty=True, default="") header: Header = json_util.field( "header", omitempty=True, default=header_cls(), decoder=header_cls.from_json ) signature: bytes = json_util.field( "signature", decoder=json_util.decode_b64jose, encoder=json_util.encode_b64jose ) @protected.encoder # type: ignore def protected(value: str) -> str: # wrong type guess (Signature, not bytes) | pylint: disable=no-member return json_util.encode_b64jose(value.encode("utf-8")) @protected.decoder # type: ignore def protected(value: str) -> str: return json_util.decode_b64jose(value).decode("utf-8") def __init__(self, **kwargs: Any) -> None: if "combined" not in kwargs: kwargs = self._with_combined(kwargs) super().__init__(**kwargs) assert self.combined.alg is not None @classmethod def _with_combined(cls, kwargs: Any) -> Dict[str, Any]: assert "combined" not in kwargs header = kwargs.get("header", cls._fields["header"].default) protected = kwargs.get("protected", cls._fields["protected"].default) if protected: combined = header + cls.header_cls.json_loads(protected) else: combined = header kwargs["combined"] = combined return kwargs @classmethod def _msg(cls, protected: str, payload: bytes) -> bytes: return b64.b64encode(protected.encode("utf-8")) + b"." + b64.b64encode(payload) def verify(self, payload: bytes, key: Optional[josepy.JWK] = None) -> bool: """Verify. :param bytes payload: Payload to verify. :param JWK key: Key used for verification. """ actual_key: josepy.JWK = self.combined.find_key() if key is None else key if not self.combined.alg: raise josepy.Error("Not signature algorithm defined.") return self.combined.alg.verify( key=actual_key.key, sig=self.signature, msg=self._msg(self.protected, payload) ) @classmethod def sign( cls, payload: bytes, key: josepy.JWK, alg: josepy.JWASignature, include_jwk: bool = True, protect: FrozenSet = frozenset(), **kwargs: Any, ) -> "Signature": """Sign. :param bytes payload: Payload to sign. :param JWK key: Key for signature. :param JWASignature alg: Signature algorithm to use to sign. :param bool include_jwk: If True, insert the JWK inside the signature headers. :param FrozenSet protect: List of headers to protect. """ assert isinstance(key, alg.kty) header_params = kwargs header_params["alg"] = alg if include_jwk: header_params["jwk"] = key.public_key() assert set(header_params).issubset(cls.header_cls._fields) assert protect.issubset(cls.header_cls._fields) protected_params = {} for header in protect: if header in header_params: protected_params[header] = header_params.pop(header) if protected_params: protected = cls.header_cls(**protected_params).json_dumps() else: protected = "" header = cls.header_cls(**header_params) signature = alg.sign(key.key, cls._msg(protected, payload)) return cls(protected=protected, header=header, signature=signature) def fields_to_partial_json(self) -> Dict[str, Any]: fields = super().fields_to_partial_json() if not fields["header"].not_omitted(): del fields["header"] return fields @classmethod def fields_from_json(cls, jobj: Mapping[str, Any]) -> Dict[str, Any]: fields = super().fields_from_json(jobj) fields_with_combined = cls._with_combined(fields) if "alg" not in fields_with_combined["combined"].not_omitted(): raise errors.DeserializationError("alg not present") return fields_with_combined class JWS(json_util.JSONObjectWithFields): """JSON Web Signature. :ivar str payload: JWS Payload. :ivar str signature: JWS Signatures. """ __slots__ = ("payload", "signatures") payload: bytes signatures: List[Signature] signature_cls = Signature def verify(self, key: Optional[josepy.JWK] = None) -> bool: """Verify.""" return all(sig.verify(self.payload, key) for sig in self.signatures) @classmethod def sign(cls, payload: bytes, **kwargs: Any) -> "JWS": """Sign.""" return cls(payload=payload, signatures=(cls.signature_cls.sign(payload=payload, **kwargs),)) @property def signature(self) -> Signature: """Get a singleton signature. :rtype: :class:`JWS.signature_cls` """ assert len(self.signatures) == 1 return self.signatures[0] def to_compact(self) -> bytes: """Compact serialization. :rtype: bytes """ assert len(self.signatures) == 1 assert "alg" not in self.signature.header.not_omitted() # ... it must be in protected return ( b64.b64encode(self.signature.protected.encode("utf-8")) + b"." + b64.b64encode(self.payload) + b"." + b64.b64encode(self.signature.signature) ) @classmethod def from_compact(cls, compact: bytes) -> "JWS": """Compact deserialization. :param bytes compact: """ try: protected, payload, signature = compact.split(b".") except ValueError: raise errors.DeserializationError( "Compact JWS serialization should comprise of exactly" " 3 dot-separated components" ) sig = cls.signature_cls( protected=b64.b64decode(protected).decode("utf-8"), signature=b64.b64decode(signature) ) return cls(payload=b64.b64decode(payload), signatures=(sig,)) def to_partial_json(self, flat: bool = True) -> Dict[str, Any]: assert self.signatures payload = json_util.encode_b64jose(self.payload) if flat and len(self.signatures) == 1: ret = self.signatures[0].to_partial_json() ret["payload"] = payload return ret else: return { "payload": payload, "signatures": self.signatures, } @classmethod def from_json(cls, jobj: Mapping[str, Any]) -> "JWS": if "signature" in jobj and "signatures" in jobj: raise errors.DeserializationError("Flat mixed with non-flat") elif "signature" in jobj: # flat filtered = {key: value for key, value in jobj.items() if key != "payload"} return cls( payload=json_util.decode_b64jose(jobj["payload"]), signatures=(cls.signature_cls.from_json(filtered),), ) else: return cls( payload=json_util.decode_b64jose(jobj["payload"]), signatures=tuple(cls.signature_cls.from_json(sig) for sig in jobj["signatures"]), ) class CLI: """JWS CLI.""" @classmethod def sign(cls, args: argparse.Namespace) -> None: """Sign.""" key = args.alg.kty.load(args.key.read()) args.key.close() if args.protect is None: args.protect = [] if args.compact: args.protect.append("alg") sig = JWS.sign( payload=sys.stdin.read().encode(), key=key, alg=args.alg, protect=set(args.protect) ) if args.compact: print(sig.to_compact().decode("utf-8")) else: # JSON print(sig.json_dumps_pretty()) @classmethod def verify(cls, args: argparse.Namespace) -> bool: """Verify.""" if args.compact: sig = JWS.from_compact(sys.stdin.read().encode()) else: # JSON try: sig = cast(JWS, JWS.json_loads(sys.stdin.read())) except errors.Error as error: print(error) return False if args.key is not None: assert args.kty is not None key = args.kty.load(args.key.read()).public_key() args.key.close() else: key = None sys.stdout.write(sig.payload.decode()) return not sig.verify(key=key) @classmethod def _alg_type(cls, arg: Any) -> jwa.JWASignature: return jwa.JWASignature.from_json(arg) @classmethod def _header_type(cls, arg: Any) -> Any: assert arg in Signature.header_cls._fields return arg @classmethod def _kty_type(cls, arg: Any) -> Type[jwk_mod.JWK]: assert arg in jwk_mod.JWK.TYPES return jwk_mod.JWK.TYPES[arg] @classmethod def run(cls, args: Optional[List[str]] = None) -> Optional[bool]: """Parse arguments and sign/verify.""" if args is None: args = sys.argv[1:] parser = argparse.ArgumentParser() parser.add_argument("--compact", action="store_true") subparsers = parser.add_subparsers() parser_sign = subparsers.add_parser("sign") parser_sign.set_defaults(func=cls.sign) parser_sign.add_argument("-k", "--key", type=argparse.FileType("rb"), required=True) parser_sign.add_argument("-a", "--alg", type=cls._alg_type, default=jwa.RS256) parser_sign.add_argument("-p", "--protect", action="append", type=cls._header_type) parser_verify = subparsers.add_parser("verify") parser_verify.set_defaults(func=cls.verify) parser_verify.add_argument("-k", "--key", type=argparse.FileType("rb"), required=False) parser_verify.add_argument("--kty", type=cls._kty_type, required=False) parsed = parser.parse_args(args) return parsed.func(parsed) if __name__ == "__main__": exit(CLI.run()) # pragma: no cover
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