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venv/lib/python3.11/site-packages/jwcrypto/common.py

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+# Copyright (C) 2015 JWCrypto Project Contributors - see LICENSE file
+
+import copy
+import json
+from base64 import urlsafe_b64decode, urlsafe_b64encode
+from collections import namedtuple
+from collections.abc import MutableMapping
+
+# Padding stripping versions as described in
+# RFC 7515 Appendix C
+
+
+def base64url_encode(payload):
+    if not isinstance(payload, bytes):
+        payload = payload.encode('utf-8')
+    encode = urlsafe_b64encode(payload)
+    return encode.decode('utf-8').rstrip('=')
+
+
+def base64url_decode(payload):
+    size = len(payload) % 4
+    if size == 2:
+        payload += '=='
+    elif size == 3:
+        payload += '='
+    elif size != 0:
+        raise ValueError('Invalid base64 string')
+    return urlsafe_b64decode(payload.encode('utf-8'))
+
+
+# JSON encoding/decoding helpers with good defaults
+
+def json_encode(string):
+    if isinstance(string, bytes):
+        string = string.decode('utf-8')
+    return json.dumps(string, separators=(',', ':'), sort_keys=True)
+
+
+def json_decode(string):
+    if isinstance(string, bytes):
+        string = string.decode('utf-8')
+    return json.loads(string)
+
+
+class JWException(Exception):
+    pass
+
+
+class InvalidJWAAlgorithm(JWException):
+    def __init__(self, message=None):
+        msg = 'Invalid JWA Algorithm name'
+        if message:
+            msg += ' (%s)' % message
+        super(InvalidJWAAlgorithm, self).__init__(msg)
+
+
+class InvalidCEKeyLength(JWException):
+    """Invalid CEK Key Length.
+
+    This exception is raised when a Content Encryption Key does not match
+    the required length.
+    """
+
+    def __init__(self, expected, obtained):
+        msg = 'Expected key of length %d bits, got %d' % (expected, obtained)
+        super(InvalidCEKeyLength, self).__init__(msg)
+
+
+class InvalidJWEOperation(JWException):
+    """Invalid JWS Object.
+
+    This exception is raised when a requested operation cannot
+    be execute due to unsatisfied conditions.
+    """
+
+    def __init__(self, message=None, exception=None):
+        msg = None
+        if message:
+            msg = message
+        else:
+            msg = 'Unknown Operation Failure'
+        if exception:
+            msg += ' {%s}' % repr(exception)
+        super(InvalidJWEOperation, self).__init__(msg)
+
+
+class InvalidJWEKeyType(JWException):
+    """Invalid JWE Key Type.
+
+    This exception is raised when the provided JWK Key does not match
+    the type required by the specified algorithm.
+    """
+
+    def __init__(self, expected, obtained):
+        msg = 'Expected key type %s, got %s' % (expected, obtained)
+        super(InvalidJWEKeyType, self).__init__(msg)
+
+
+class InvalidJWEKeyLength(JWException):
+    """Invalid JWE Key Length.
+
+    This exception is raised when the provided JWK Key does not match
+    the length required by the specified algorithm.
+    """
+
+    def __init__(self, expected, obtained):
+        msg = 'Expected key of length %d, got %d' % (expected, obtained)
+        super(InvalidJWEKeyLength, self).__init__(msg)
+
+
+class InvalidJWSERegOperation(JWException):
+    """Invalid JWSE Header Registry Operation.
+
+    This exception is raised when there is an error in trying to add a JW
+    Signature or Encryption header to the Registry.
+    """
+
+    def __init__(self, message=None, exception=None):
+        msg = None
+        if message:
+            msg = message
+        else:
+            msg = 'Unknown Operation Failure'
+        if exception:
+            msg += ' {%s}' % repr(exception)
+        super(InvalidJWSERegOperation, self).__init__(msg)
+
+
+class JWKeyNotFound(JWException):
+    """The key needed to complete the operation was not found.
+
+    This exception is raised when a JWKSet is used to perform
+    some operation and the key required to successfully complete
+    the operation is not found.
+    """
+
+    def __init__(self, message=None):
+        if message:
+            msg = message
+        else:
+            msg = 'Key Not Found'
+        super(JWKeyNotFound, self).__init__(msg)
+
+
+# JWSE Header Registry definitions
+
+# RFC 7515 - 9.1: JSON Web Signature and Encryption Header Parameters Registry
+# HeaderParameters are for both JWS and JWE
+JWSEHeaderParameter = namedtuple('Parameter',
+                                 'description mustprotect supported check_fn')
+
+
+class JWSEHeaderRegistry(MutableMapping):
+    def __init__(self, init_registry=None):
+        if init_registry:
+            if isinstance(init_registry, dict):
+                self._registry = copy.deepcopy(init_registry)
+            else:
+                raise InvalidJWSERegOperation('Unknown input type')
+        else:
+            self._registry = {}
+
+        MutableMapping.__init__(self)
+
+    def check_header(self, h, value):
+        if h not in self._registry:
+            raise InvalidJWSERegOperation('No header "%s" found in registry'
+                                          % h)
+
+        param = self._registry[h]
+        if param.check_fn is None:
+            return True
+        else:
+            return param.check_fn(value)
+
+    def __getitem__(self, key):
+        return self._registry.__getitem__(key)
+
+    def __iter__(self):
+        return self._registry.__iter__()
+
+    def __delitem__(self, key):
+        if self._registry[key].mustprotect or \
+           self._registry[key].supported:
+            raise InvalidJWSERegOperation('Unable to delete protected or '
+                                          'supported field')
+        else:
+            self._registry.__delitem__(key)
+
+    def __setitem__(self, h, jwse_header_param):
+        # Check if a header is not supported
+        if h in self._registry:
+            p = self._registry[h]
+            if p.supported:
+                raise InvalidJWSERegOperation('Supported header already exists'
+                                              ' in registry')
+            elif p.mustprotect and not jwse_header_param.mustprotect:
+                raise InvalidJWSERegOperation('Header specified should be'
+                                              'a protected header')
+            else:
+                del self._registry[h]
+
+        self._registry[h] = jwse_header_param
+
+    def __len__(self):
+        return self._registry.__len__()