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"""JSON Web Signature."""
import argparse
import base64
import sys
from typing import (
Any,
Dict,
FrozenSet,
List,
Mapping,
Optional,
Tuple,
Type,
cast,
)
from OpenSSL import crypto
import josepy
from josepy import b64, errors, json_util, jwa
from josepy import jwk as jwk_mod
from josepy import util
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[util.ComparableX509, ...] = 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):
return [
base64.b64encode(crypto.dump_certificate(crypto.FILETYPE_ASN1, cert.wrapped))
for cert in value
]
@x5c.decoder # type: ignore
def x5c(value):
try:
return tuple(
util.ComparableX509(
crypto.load_certificate(crypto.FILETYPE_ASN1, base64.b64decode(cert))
)
for cert in value
)
except crypto.Error 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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