351 lines
13 KiB
Python
351 lines
13 KiB
Python
from authlib.common.encoding import json_b64encode
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from authlib.common.encoding import to_bytes
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from authlib.common.encoding import to_unicode
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from authlib.common.encoding import urlsafe_b64encode
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from authlib.jose.errors import BadSignatureError
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from authlib.jose.errors import DecodeError
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from authlib.jose.errors import InvalidCritHeaderParameterNameError
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from authlib.jose.errors import InvalidHeaderParameterNameError
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from authlib.jose.errors import MissingAlgorithmError
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from authlib.jose.errors import UnsupportedAlgorithmError
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from authlib.jose.util import ensure_dict
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from authlib.jose.util import extract_header
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from authlib.jose.util import extract_segment
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from .models import JWSHeader
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from .models import JWSObject
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class JsonWebSignature:
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#: Registered Header Parameter Names defined by Section 4.1
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REGISTERED_HEADER_PARAMETER_NAMES = frozenset(
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[
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"alg",
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"jku",
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"jwk",
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"kid",
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"x5u",
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"x5c",
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"x5t",
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"x5t#S256",
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"typ",
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"cty",
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"crit",
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]
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)
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MAX_CONTENT_LENGTH: int = 256000
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#: Defined available JWS algorithms in the registry
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ALGORITHMS_REGISTRY = {}
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def __init__(self, algorithms=None, private_headers=None):
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self._private_headers = private_headers
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self._algorithms = algorithms
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@classmethod
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def register_algorithm(cls, algorithm):
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if not algorithm or algorithm.algorithm_type != "JWS":
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raise ValueError(f"Invalid algorithm for JWS, {algorithm!r}")
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cls.ALGORITHMS_REGISTRY[algorithm.name] = algorithm
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def serialize_compact(self, protected, payload, key):
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"""Generate a JWS Compact Serialization. The JWS Compact Serialization
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represents digitally signed or MACed content as a compact, URL-safe
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string, per `Section 7.1`_.
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.. code-block:: text
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BASE64URL(UTF8(JWS Protected Header)) || '.' ||
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BASE64URL(JWS Payload) || '.' ||
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BASE64URL(JWS Signature)
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:param protected: A dict of protected header
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:param payload: A bytes/string of payload
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:param key: Private key used to generate signature
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:return: byte
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"""
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jws_header = JWSHeader(protected, None)
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self._validate_private_headers(protected)
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self._validate_crit_headers(protected)
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algorithm, key = self._prepare_algorithm_key(protected, payload, key)
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protected_segment = json_b64encode(jws_header.protected)
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payload_segment = urlsafe_b64encode(to_bytes(payload))
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# calculate signature
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signing_input = b".".join([protected_segment, payload_segment])
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signature = urlsafe_b64encode(algorithm.sign(signing_input, key))
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return b".".join([protected_segment, payload_segment, signature])
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def deserialize_compact(self, s, key, decode=None):
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"""Exact JWS Compact Serialization, and validate with the given key.
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If key is not provided, the returned dict will contain the signature,
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and signing input values. Via `Section 7.1`_.
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:param s: text of JWS Compact Serialization
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:param key: key used to verify the signature
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:param decode: a function to decode payload data
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:return: JWSObject
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:raise: BadSignatureError
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.. _`Section 7.1`: https://tools.ietf.org/html/rfc7515#section-7.1
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"""
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if len(s) > self.MAX_CONTENT_LENGTH:
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raise ValueError("Serialization is too long.")
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try:
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s = to_bytes(s)
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signing_input, signature_segment = s.rsplit(b".", 1)
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protected_segment, payload_segment = signing_input.split(b".", 1)
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except ValueError as exc:
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raise DecodeError("Not enough segments") from exc
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protected = _extract_header(protected_segment)
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self._validate_crit_headers(protected)
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jws_header = JWSHeader(protected, None)
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payload = _extract_payload(payload_segment)
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if decode:
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payload = decode(payload)
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signature = _extract_signature(signature_segment)
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rv = JWSObject(jws_header, payload, "compact")
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algorithm, key = self._prepare_algorithm_key(jws_header, payload, key)
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if algorithm.verify(signing_input, signature, key):
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return rv
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raise BadSignatureError(rv)
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def serialize_json(self, header_obj, payload, key):
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"""Generate a JWS JSON Serialization. The JWS JSON Serialization
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represents digitally signed or MACed content as a JSON object,
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per `Section 7.2`_.
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:param header_obj: A dict/list of header
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:param payload: A string/dict of payload
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:param key: Private key used to generate signature
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:return: JWSObject
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Example ``header_obj`` of JWS JSON Serialization::
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{
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"protected: {"alg": "HS256"},
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"header": {"kid": "jose"}
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}
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Pass a dict to generate flattened JSON Serialization, pass a list of
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header dict to generate standard JSON Serialization.
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"""
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payload_segment = json_b64encode(payload)
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def _sign(jws_header):
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self._validate_private_headers(jws_header)
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# RFC 7515 §4.1.11: 'crit' MUST be integrity-protected.
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# Reject if present in unprotected header, and validate only
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# against the protected header parameters.
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self._reject_unprotected_crit(jws_header.header)
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self._validate_crit_headers(jws_header.protected)
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_alg, _key = self._prepare_algorithm_key(jws_header, payload, key)
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protected_segment = json_b64encode(jws_header.protected)
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signing_input = b".".join([protected_segment, payload_segment])
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signature = urlsafe_b64encode(_alg.sign(signing_input, _key))
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rv = {
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"protected": to_unicode(protected_segment),
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"signature": to_unicode(signature),
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}
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if jws_header.header is not None:
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rv["header"] = jws_header.header
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return rv
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if isinstance(header_obj, dict):
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data = _sign(JWSHeader.from_dict(header_obj))
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data["payload"] = to_unicode(payload_segment)
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return data
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signatures = [_sign(JWSHeader.from_dict(h)) for h in header_obj]
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return {"payload": to_unicode(payload_segment), "signatures": signatures}
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def deserialize_json(self, obj, key, decode=None):
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"""Exact JWS JSON Serialization, and validate with the given key.
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If key is not provided, it will return a dict without signature
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verification. Header will still be validated. Via `Section 7.2`_.
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:param obj: text of JWS JSON Serialization
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:param key: key used to verify the signature
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:param decode: a function to decode payload data
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:return: JWSObject
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:raise: BadSignatureError
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.. _`Section 7.2`: https://tools.ietf.org/html/rfc7515#section-7.2
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"""
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obj = ensure_dict(obj, "JWS")
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payload_segment = obj.get("payload")
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if payload_segment is None:
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raise DecodeError('Missing "payload" value')
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payload_segment = to_bytes(payload_segment)
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payload = _extract_payload(payload_segment)
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if decode:
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payload = decode(payload)
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if "signatures" not in obj:
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# flattened JSON JWS
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jws_header, valid = self._validate_json_jws(
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payload_segment, payload, obj, key
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)
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rv = JWSObject(jws_header, payload, "flat")
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if valid:
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return rv
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raise BadSignatureError(rv)
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headers = []
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is_valid = True
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for header_obj in obj["signatures"]:
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jws_header, valid = self._validate_json_jws(
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payload_segment, payload, header_obj, key
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)
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headers.append(jws_header)
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if not valid:
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is_valid = False
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rv = JWSObject(headers, payload, "json")
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if is_valid:
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return rv
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raise BadSignatureError(rv)
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def serialize(self, header, payload, key):
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"""Generate a JWS Serialization. It will automatically generate a
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Compact or JSON Serialization depending on the given header. If a
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header is in a JSON header format, it will call
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:meth:`serialize_json`, otherwise it will call
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:meth:`serialize_compact`.
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:param header: A dict/list of header
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:param payload: A string/dict of payload
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:param key: Private key used to generate signature
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:return: byte/dict
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"""
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if isinstance(header, (list, tuple)):
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return self.serialize_json(header, payload, key)
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if "protected" in header:
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return self.serialize_json(header, payload, key)
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return self.serialize_compact(header, payload, key)
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def deserialize(self, s, key, decode=None):
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"""Deserialize JWS Serialization, both compact and JSON format.
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It will automatically deserialize depending on the given JWS.
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:param s: text of JWS Compact/JSON Serialization
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:param key: key used to verify the signature
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:param decode: a function to decode payload data
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:return: dict
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:raise: BadSignatureError
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If key is not provided, it will still deserialize the serialization
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without verification.
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"""
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if isinstance(s, dict):
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return self.deserialize_json(s, key, decode)
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s = to_bytes(s)
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if s.startswith(b"{") and s.endswith(b"}"):
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return self.deserialize_json(s, key, decode)
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return self.deserialize_compact(s, key, decode)
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def _prepare_algorithm_key(self, header, payload, key):
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if "alg" not in header:
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raise MissingAlgorithmError()
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alg = header["alg"]
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if self._algorithms is not None and alg not in self._algorithms:
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raise UnsupportedAlgorithmError()
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if alg not in self.ALGORITHMS_REGISTRY:
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raise UnsupportedAlgorithmError()
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algorithm = self.ALGORITHMS_REGISTRY[alg]
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if callable(key):
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key = key(header, payload)
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elif key is None and "jwk" in header:
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key = header["jwk"]
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key = algorithm.prepare_key(key)
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return algorithm, key
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def _validate_private_headers(self, header):
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# only validate private headers when developers set
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# private headers explicitly
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if self._private_headers is not None:
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names = self.REGISTERED_HEADER_PARAMETER_NAMES.copy()
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names = names.union(self._private_headers)
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for k in header:
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if k not in names:
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raise InvalidHeaderParameterNameError(k)
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def _reject_unprotected_crit(self, unprotected_header):
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"""Reject 'crit' when found in the unprotected header (RFC 7515 §4.1.11)."""
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if unprotected_header and "crit" in unprotected_header:
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raise InvalidHeaderParameterNameError("crit")
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def _validate_crit_headers(self, header):
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if "crit" in header:
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crit_headers = header["crit"]
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# Type enforcement for robustness and predictable errors
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if not isinstance(crit_headers, list) or not all(
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isinstance(x, str) for x in crit_headers
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):
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raise InvalidHeaderParameterNameError("crit")
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names = self.REGISTERED_HEADER_PARAMETER_NAMES.copy()
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if self._private_headers:
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names = names.union(self._private_headers)
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for k in crit_headers:
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if k not in names:
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raise InvalidCritHeaderParameterNameError(k)
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elif k not in header:
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raise InvalidCritHeaderParameterNameError(k)
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def _validate_json_jws(self, payload_segment, payload, header_obj, key):
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protected_segment = header_obj.get("protected")
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if not protected_segment:
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raise DecodeError('Missing "protected" value')
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signature_segment = header_obj.get("signature")
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if not signature_segment:
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raise DecodeError('Missing "signature" value')
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protected_segment = to_bytes(protected_segment)
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protected = _extract_header(protected_segment)
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header = header_obj.get("header")
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if header and not isinstance(header, dict):
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raise DecodeError('Invalid "header" value')
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# RFC 7515 §4.1.11: 'crit' MUST be integrity-protected. If present in
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# the unprotected header object, reject the JWS.
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self._reject_unprotected_crit(header)
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# Enforce must-understand semantics for names listed in protected
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# 'crit'. This will also ensure each listed name is present in the
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# protected header.
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self._validate_crit_headers(protected)
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jws_header = JWSHeader(protected, header)
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algorithm, key = self._prepare_algorithm_key(jws_header, payload, key)
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signing_input = b".".join([protected_segment, payload_segment])
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signature = _extract_signature(to_bytes(signature_segment))
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if algorithm.verify(signing_input, signature, key):
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return jws_header, True
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return jws_header, False
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def _extract_header(header_segment):
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return extract_header(header_segment, DecodeError)
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def _extract_signature(signature_segment):
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return extract_segment(signature_segment, DecodeError, "signature")
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def _extract_payload(payload_segment):
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return extract_segment(payload_segment, DecodeError, "payload")
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