/usr/lib/python2.7/dist-packages/jwcrypto/jwe.py is in python-jwcrypto 0.4.2-1.
This file is owned by root:root, with mode 0o644.
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import zlib
from jwcrypto import common
from jwcrypto.common import base64url_decode, base64url_encode
from jwcrypto.common import json_decode, json_encode
from jwcrypto.jwa import JWA
# RFC 7516 - 4.1
# name: (description, supported?)
JWEHeaderRegistry = {'alg': ('Algorithm', True),
'enc': ('Encryption Algorithm', True),
'zip': ('Compression Algorithm', True),
'jku': ('JWK Set URL', False),
'jwk': ('JSON Web Key', False),
'kid': ('Key ID', True),
'x5u': ('X.509 URL', False),
'x5c': ('X.509 Certificate Chain', False),
'x5t': ('X.509 Certificate SHA-1 Thumbprint', False),
'x5t#S256': ('X.509 Certificate SHA-256 Thumbprint',
False),
'typ': ('Type', True),
'cty': ('Content Type', True),
'crit': ('Critical', True)}
"""Registry of valid header parameters"""
default_allowed_algs = [
# Key Management Algorithms
'RSA1_5', 'RSA-OAEP', 'RSA-OAEP-256',
'A128KW', 'A192KW', 'A256KW',
'dir',
'ECDH-ES', 'ECDH-ES+A128KW', 'ECDH-ES+A192KW', 'ECDH-ES+A256KW',
'A128GCMKW', 'A192GCMKW', 'A256GCMKW',
'PBES2-HS256+A128KW', 'PBES2-HS384+A192KW', 'PBES2-HS512+A256KW',
# Content Encryption Algoritms
'A128CBC-HS256', 'A192CBC-HS384', 'A256CBC-HS512',
'A128GCM', 'A192GCM', 'A256GCM']
"""Default allowed algorithms"""
class InvalidJWEData(Exception):
"""Invalid JWE Object.
This exception is raised when the JWE Object is invalid and/or
improperly formatted.
"""
def __init__(self, message=None, exception=None):
msg = None
if message:
msg = message
else:
msg = 'Unknown Data Verification Failure'
if exception:
msg += ' {%s}' % str(exception)
super(InvalidJWEData, self).__init__(msg)
# These have been moved to jwcrypto.common, maintain here for bacwards compat
InvalidCEKeyLength = common.InvalidCEKeyLength
InvalidJWEKeyLength = common.InvalidJWEKeyLength
InvalidJWEKeyType = common.InvalidJWEKeyType
InvalidJWEOperation = common.InvalidJWEOperation
class JWE(object):
"""JSON Web Encryption object
This object represent a JWE token.
"""
def __init__(self, plaintext=None, protected=None, unprotected=None,
aad=None, algs=None, recipient=None, header=None):
"""Creates a JWE token.
:param plaintext(bytes): An arbitrary plaintext to be encrypted.
:param protected: A JSON string with the protected header.
:param unprotected: A JSON string with the shared unprotected header.
:param aad(bytes): Arbitrary additional authenticated data
:param algs: An optional list of allowed algorithms
:param recipient: An optional, default recipient key
:param header: An optional header for the default recipient
"""
self._allowed_algs = None
self.objects = dict()
self.plaintext = None
if plaintext is not None:
if isinstance(plaintext, bytes):
self.plaintext = plaintext
else:
self.plaintext = plaintext.encode('utf-8')
self.cek = None
self.decryptlog = None
if aad:
self.objects['aad'] = aad
if protected:
if isinstance(protected, dict):
protected = json_encode(protected)
else:
json_decode(protected) # check header encoding
self.objects['protected'] = protected
if unprotected:
if isinstance(unprotected, dict):
unprotected = json_encode(unprotected)
else:
json_decode(unprotected) # check header encoding
self.objects['unprotected'] = unprotected
if algs:
self.allowed_algs = algs
if recipient:
self.add_recipient(recipient, header=header)
elif header:
raise ValueError('Header is allowed only with default recipient')
def _jwa_keymgmt(self, name):
allowed = self._allowed_algs or default_allowed_algs
if name not in allowed:
raise InvalidJWEOperation('Algorithm not allowed')
return JWA.keymgmt_alg(name)
def _jwa_enc(self, name):
allowed = self._allowed_algs or default_allowed_algs
if name not in allowed:
raise InvalidJWEOperation('Algorithm not allowed')
return JWA.encryption_alg(name)
@property
def allowed_algs(self):
"""Allowed algorithms.
The list of allowed algorithms.
Can be changed by setting a list of algorithm names.
"""
if self._allowed_algs:
return self._allowed_algs
else:
return default_allowed_algs
@allowed_algs.setter
def allowed_algs(self, algs):
if not isinstance(algs, list):
raise TypeError('Allowed Algs must be a list')
self._allowed_algs = algs
def _merge_headers(self, h1, h2):
for k in list(h1.keys()):
if k in h2:
raise InvalidJWEData('Duplicate header: "%s"' % k)
h1.update(h2)
return h1
def _get_jose_header(self, header=None):
jh = dict()
if 'protected' in self.objects:
ph = json_decode(self.objects['protected'])
jh = self._merge_headers(jh, ph)
if 'unprotected' in self.objects:
uh = json_decode(self.objects['unprotected'])
jh = self._merge_headers(jh, uh)
if header:
rh = json_decode(header)
jh = self._merge_headers(jh, rh)
return jh
def _get_alg_enc_from_headers(self, jh):
algname = jh.get('alg', None)
if algname is None:
raise InvalidJWEData('Missing "alg" from headers')
alg = self._jwa_keymgmt(algname)
encname = jh.get('enc', None)
if encname is None:
raise InvalidJWEData('Missing "enc" from headers')
enc = self._jwa_enc(encname)
return alg, enc
def _encrypt(self, alg, enc, jh):
aad = base64url_encode(self.objects.get('protected', ''))
if 'aad' in self.objects:
aad += '.' + base64url_encode(self.objects['aad'])
aad = aad.encode('utf-8')
compress = jh.get('zip', None)
if compress == 'DEF':
data = zlib.compress(self.plaintext)[2:-4]
elif compress is None:
data = self.plaintext
else:
raise ValueError('Unknown compression')
iv, ciphertext, tag = enc.encrypt(self.cek, aad, data)
self.objects['iv'] = iv
self.objects['ciphertext'] = ciphertext
self.objects['tag'] = tag
def add_recipient(self, key, header=None):
"""Encrypt the plaintext with the given key.
:param key: A JWK key or password of appropriate type for the 'alg'
provided in the JOSE Headers.
:param header: A JSON string representing the per-recipient header.
:raises ValueError: if the plaintext is missing or not of type bytes.
:raises ValueError: if the compression type is unknown.
:raises InvalidJWAAlgorithm: if the 'alg' provided in the JOSE
headers is missing or unknown, or otherwise not implemented.
"""
if self.plaintext is None:
raise ValueError('Missing plaintext')
if not isinstance(self.plaintext, bytes):
raise ValueError("Plaintext must be 'bytes'")
if isinstance(header, dict):
header = json_encode(header)
jh = self._get_jose_header(header)
alg, enc = self._get_alg_enc_from_headers(jh)
rec = dict()
if header:
rec['header'] = header
wrapped = alg.wrap(key, enc.wrap_key_size, self.cek, jh)
self.cek = wrapped['cek']
if 'ek' in wrapped:
rec['encrypted_key'] = wrapped['ek']
if 'header' in wrapped:
h = json_decode(rec.get('header', '{}'))
nh = self._merge_headers(h, wrapped['header'])
rec['header'] = json_encode(nh)
if 'ciphertext' not in self.objects:
self._encrypt(alg, enc, jh)
if 'recipients' in self.objects:
self.objects['recipients'].append(rec)
elif 'encrypted_key' in self.objects or 'header' in self.objects:
self.objects['recipients'] = list()
n = dict()
if 'encrypted_key' in self.objects:
n['encrypted_key'] = self.objects.pop('encrypted_key')
if 'header' in self.objects:
n['header'] = self.objects.pop('header')
self.objects['recipients'].append(n)
self.objects['recipients'].append(rec)
else:
self.objects.update(rec)
def serialize(self, compact=False):
"""Serializes the object into a JWE token.
:param compact(boolean): if True generates the compact
representation, otherwise generates a standard JSON format.
:raises InvalidJWEOperation: if the object cannot serialized
with the compact representation and `compact` is True.
:raises InvalidJWEOperation: if no recipients have been added
to the object.
"""
if 'ciphertext' not in self.objects:
raise InvalidJWEOperation("No available ciphertext")
if compact:
for invalid in 'aad', 'unprotected':
if invalid in self.objects:
raise InvalidJWEOperation("Can't use compact encoding")
if 'recipients' in self.objects:
if len(self.objects['recipients']) != 1:
raise InvalidJWEOperation("Invalid number of recipients")
rec = self.objects['recipients'][0]
else:
rec = self.objects
if 'header' in rec:
# The AESGCMKW algorithm generates data (iv, tag) we put in the
# per-recipient unpotected header by default. Move it to the
# protected header and re-encrypt the payload, as the protected
# header is used as additional authenticated data.
h = json_decode(rec['header'])
ph = json_decode(self.objects['protected'])
nph = self._merge_headers(h, ph)
self.objects['protected'] = json_encode(nph)
jh = self._get_jose_header()
alg, enc = self._get_alg_enc_from_headers(jh)
self._encrypt(alg, enc, jh)
del rec['header']
return '.'.join([base64url_encode(self.objects['protected']),
base64url_encode(rec.get('encrypted_key', '')),
base64url_encode(self.objects['iv']),
base64url_encode(self.objects['ciphertext']),
base64url_encode(self.objects['tag'])])
else:
obj = self.objects
enc = {'ciphertext': base64url_encode(obj['ciphertext']),
'iv': base64url_encode(obj['iv']),
'tag': base64url_encode(self.objects['tag'])}
if 'protected' in obj:
enc['protected'] = base64url_encode(obj['protected'])
if 'unprotected' in obj:
enc['unprotected'] = json_decode(obj['unprotected'])
if 'aad' in obj:
enc['aad'] = base64url_encode(obj['aad'])
if 'recipients' in obj:
enc['recipients'] = list()
for rec in obj['recipients']:
e = dict()
if 'encrypted_key' in rec:
e['encrypted_key'] = \
base64url_encode(rec['encrypted_key'])
if 'header' in rec:
e['header'] = json_decode(rec['header'])
enc['recipients'].append(e)
else:
if 'encrypted_key' in obj:
enc['encrypted_key'] = \
base64url_encode(obj['encrypted_key'])
if 'header' in obj:
enc['header'] = json_decode(obj['header'])
return json_encode(enc)
def _check_crit(self, crit):
for k in crit:
if k not in JWEHeaderRegistry:
raise InvalidJWEData('Unknown critical header: "%s"' % k)
else:
if not JWEHeaderRegistry[k][1]:
raise InvalidJWEData('Unsupported critical header: '
'"%s"' % k)
# FIXME: allow to specify which algorithms to accept as valid
def _decrypt(self, key, ppe):
jh = self._get_jose_header(ppe.get('header', None))
# TODO: allow caller to specify list of headers it understands
self._check_crit(jh.get('crit', dict()))
alg = self._jwa_keymgmt(jh.get('alg', None))
enc = self._jwa_enc(jh.get('enc', None))
aad = base64url_encode(self.objects.get('protected', ''))
if 'aad' in self.objects:
aad += '.' + base64url_encode(self.objects['aad'])
cek = alg.unwrap(key, enc.wrap_key_size,
ppe.get('encrypted_key', b''), jh)
data = enc.decrypt(cek, aad.encode('utf-8'),
self.objects['iv'],
self.objects['ciphertext'],
self.objects['tag'])
self.decryptlog.append('Success')
self.cek = cek
compress = jh.get('zip', None)
if compress == 'DEF':
self.plaintext = zlib.decompress(data, -zlib.MAX_WBITS)
elif compress is None:
self.plaintext = data
else:
raise ValueError('Unknown compression')
def decrypt(self, key):
"""Decrypt a JWE token.
:param key: The (:class:`jwcrypto.jwk.JWK`) decryption key.
:param key: A (:class:`jwcrypto.jwk.JWK`) decryption key or a password
string (optional).
:raises InvalidJWEOperation: if the key is not a JWK object.
:raises InvalidJWEData: if the ciphertext can't be decrypted or
the object is otherwise malformed.
"""
if 'ciphertext' not in self.objects:
raise InvalidJWEOperation("No available ciphertext")
self.decryptlog = list()
if 'recipients' in self.objects:
for rec in self.objects['recipients']:
try:
self._decrypt(key, rec)
except Exception as e: # pylint: disable=broad-except
self.decryptlog.append('Failed: [%s]' % repr(e))
else:
try:
self._decrypt(key, self.objects)
except Exception as e: # pylint: disable=broad-except
self.decryptlog.append('Failed: [%s]' % repr(e))
if not self.plaintext:
raise InvalidJWEData('No recipient matched the provided '
'key' + repr(self.decryptlog))
def deserialize(self, raw_jwe, key=None):
"""Deserialize a JWE token.
NOTE: Destroys any current status and tries to import the raw
JWE provided.
:param raw_jwe: a 'raw' JWE token (JSON Encoded or Compact
notation) string.
:param key: A (:class:`jwcrypto.jwk.JWK`) decryption key or a password
string (optional).
If a key is provided a decryption step will be attempted after
the object is successfully deserialized.
:raises InvalidJWEData: if the raw object is an invaid JWE token.
:raises InvalidJWEOperation: if the decryption fails.
"""
self.objects = dict()
self.plaintext = None
self.cek = None
o = dict()
try:
try:
djwe = json_decode(raw_jwe)
o['iv'] = base64url_decode(djwe['iv'])
o['ciphertext'] = base64url_decode(djwe['ciphertext'])
o['tag'] = base64url_decode(djwe['tag'])
if 'protected' in djwe:
p = base64url_decode(djwe['protected'])
o['protected'] = p.decode('utf-8')
if 'unprotected' in djwe:
o['unprotected'] = json_encode(djwe['unprotected'])
if 'aad' in djwe:
o['aad'] = base64url_decode(djwe['aad'])
if 'recipients' in djwe:
o['recipients'] = list()
for rec in djwe['recipients']:
e = dict()
if 'encrypted_key' in rec:
e['encrypted_key'] = \
base64url_decode(rec['encrypted_key'])
if 'header' in rec:
e['header'] = json_encode(rec['header'])
o['recipients'].append(e)
else:
if 'encrypted_key' in djwe:
o['encrypted_key'] = \
base64url_decode(djwe['encrypted_key'])
if 'header' in djwe:
o['header'] = json_encode(djwe['header'])
except ValueError:
c = raw_jwe.split('.')
if len(c) != 5:
raise InvalidJWEData()
p = base64url_decode(c[0])
o['protected'] = p.decode('utf-8')
ekey = base64url_decode(c[1])
if ekey != b'':
o['encrypted_key'] = base64url_decode(c[1])
o['iv'] = base64url_decode(c[2])
o['ciphertext'] = base64url_decode(c[3])
o['tag'] = base64url_decode(c[4])
self.objects = o
except Exception as e: # pylint: disable=broad-except
raise InvalidJWEData('Invalid format', repr(e))
if key:
self.decrypt(key)
@property
def payload(self):
if not self.plaintext:
raise InvalidJWEOperation("Plaintext not available")
return self.plaintext
@property
def jose_header(self):
jh = self._get_jose_header()
if len(jh) == 0:
raise InvalidJWEOperation("JOSE Header not available")
return jh
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