"""JSON Web Key."""
import abc
import binascii
import json
import logging
import cryptography.exceptions
import six
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes # type: ignore
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import ec # type: ignore
from cryptography.hazmat.primitives.asymmetric import rsa
from josepy import errors, json_util, util
logger = logging.getLogger(__name__)
class JWK(json_util.TypedJSONObjectWithFields):
# pylint: disable=too-few-public-methods
"""JSON Web Key."""
type_field_name = 'kty'
TYPES = {} # type: dict
cryptography_key_types = () # type: tuple
"""Subclasses should override."""
required = NotImplemented
"""Required members of public key's representation as defined by JWK/JWA."""
_thumbprint_json_dumps_params = {
# "no whitespace or line breaks before or after any syntactic
# elements"
'indent': None,
'separators': (',', ':'),
# "members ordered lexicographically by the Unicode [UNICODE]
# code points of the member names"
'sort_keys': True,
}
def thumbprint(self, hash_function=hashes.SHA256):
"""Compute JWK Thumbprint.
https://tools.ietf.org/html/rfc7638
:returns: bytes
"""
digest = hashes.Hash(hash_function(), backend=default_backend())
digest.update(json.dumps(
dict((k, v) for k, v in six.iteritems(self.to_json())
if k in self.required),
**self._thumbprint_json_dumps_params).encode())
return digest.finalize()
@abc.abstractmethod
def public_key(self): # pragma: no cover
"""Generate JWK with public key.
For symmetric cryptosystems, this would return ``self``.
"""
raise NotImplementedError()
@classmethod
def _load_cryptography_key(cls, data, password=None, backend=None):
backend = default_backend() if backend is None else backend
exceptions = {}
# private key?
for loader in (serialization.load_pem_private_key,
serialization.load_der_private_key):
try:
return loader(data, password, backend)
except (ValueError, TypeError,
cryptography.exceptions.UnsupportedAlgorithm) as error:
exceptions[loader] = error
# public key?
for loader in (serialization.load_pem_public_key,
serialization.load_der_public_key):
try:
return loader(data, backend)
except (ValueError,
cryptography.exceptions.UnsupportedAlgorithm) as error:
exceptions[loader] = error
# no luck
raise errors.Error('Unable to deserialize key: {0}'.format(exceptions))
@classmethod
def load(cls, data, password=None, backend=None):
"""Load serialized key as JWK.
:param str data: Public or private key serialized as PEM or DER.
:param str password: Optional password.
:param backend: A `.PEMSerializationBackend` and
`.DERSerializationBackend` provider.
:raises errors.Error: if unable to deserialize, or unsupported
JWK algorithm
:returns: JWK of an appropriate type.
:rtype: `JWK`
"""
try:
key = cls._load_cryptography_key(data, password, backend)
except errors.Error as error:
logger.debug('Loading symmetric key, asymmetric failed: %s', error)
return JWKOct(key=data)
if cls.typ is not NotImplemented and not isinstance(
key, cls.cryptography_key_types):
raise errors.Error('Unable to deserialize {0} into {1}'.format(
key.__class__, cls.__class__))
for jwk_cls in six.itervalues(cls.TYPES):
if isinstance(key, jwk_cls.cryptography_key_types):
return jwk_cls(key=key)
raise errors.Error('Unsupported algorithm: {0}'.format(key.__class__))
@JWK.register
class JWKES(JWK): # pragma: no cover
# pylint: disable=abstract-class-not-used
"""ES JWK.
.. warning:: This is not yet implemented!
"""
typ = 'ES'
cryptography_key_types = (
ec.EllipticCurvePublicKey, ec.EllipticCurvePrivateKey)
required = ('crv', JWK.type_field_name, 'x', 'y')
def fields_to_partial_json(self):
raise NotImplementedError()
@classmethod
def fields_from_json(cls, jobj):
raise NotImplementedError()
def public_key(self):
raise NotImplementedError()
@JWK.register
class JWKOct(JWK):
"""Symmetric JWK."""
typ = 'oct'
__slots__ = ('key',)
required = ('k', JWK.type_field_name)
def fields_to_partial_json(self):
# TODO: An "alg" member SHOULD also be present to identify the
# algorithm intended to be used with the key, unless the
# application uses another means or convention to determine
# the algorithm used.
return {'k': json_util.encode_b64jose(self.key)}
@classmethod
def fields_from_json(cls, jobj):
return cls(key=json_util.decode_b64jose(jobj['k']))
def public_key(self):
return self
@JWK.register
class JWKRSA(JWK):
"""RSA JWK.
:ivar key: :class:`~cryptography.hazmat.primitives.asymmetric.rsa.RSAPrivateKey`
or :class:`~cryptography.hazmat.primitives.asymmetric.rsa.RSAPublicKey` wrapped
in :class:`~josepy.util.ComparableRSAKey`
"""
typ = 'RSA'
cryptography_key_types = (rsa.RSAPublicKey, rsa.RSAPrivateKey)
__slots__ = ('key',)
required = ('e', JWK.type_field_name, 'n')
def __init__(self, *args, **kwargs):
if 'key' in kwargs and not isinstance(
kwargs['key'], util.ComparableRSAKey):
kwargs['key'] = util.ComparableRSAKey(kwargs['key'])
super(JWKRSA, self).__init__(*args, **kwargs)
@classmethod
def _encode_param(cls, data):
"""Encode Base64urlUInt.
:type data: long
:rtype: unicode
"""
def _leading_zeros(arg):
if len(arg) % 2:
return '0' + arg
return arg
return json_util.encode_b64jose(binascii.unhexlify(
_leading_zeros(hex(data)[2:].rstrip('L'))))
@classmethod
def _decode_param(cls, data):
"""Decode Base64urlUInt."""
try:
return int(binascii.hexlify(json_util.decode_b64jose(data)), 16)
except ValueError: # invalid literal for long() with base 16
raise errors.DeserializationError()
def public_key(self):
return type(self)(key=self.key.public_key())
@classmethod
def fields_from_json(cls, jobj):
# pylint: disable=invalid-name
n, e = (cls._decode_param(jobj[x]) for x in ('n', 'e'))
public_numbers = rsa.RSAPublicNumbers(e=e, n=n)
if 'd' not in jobj: # public key
key = public_numbers.public_key(default_backend())
else: # private key
d = cls._decode_param(jobj['d'])
if ('p' in jobj or 'q' in jobj or 'dp' in jobj or
'dq' in jobj or 'qi' in jobj or 'oth' in jobj):
# "If the producer includes any of the other private
# key parameters, then all of the others MUST be
# present, with the exception of "oth", which MUST
# only be present when more than two prime factors
# were used."
p, q, dp, dq, qi, = all_params = tuple(
jobj.get(x) for x in ('p', 'q', 'dp', 'dq', 'qi'))
if tuple(param for param in all_params if param is None):
raise errors.Error(
'Some private parameters are missing: {0}'.format(
all_params))
p, q, dp, dq, qi = tuple(
cls._decode_param(x) for x in all_params)
# TODO: check for oth
else:
# cryptography>=0.8
p, q = rsa.rsa_recover_prime_factors(n, e, d)
dp = rsa.rsa_crt_dmp1(d, p)
dq = rsa.rsa_crt_dmq1(d, q)
qi = rsa.rsa_crt_iqmp(p, q)
key = rsa.RSAPrivateNumbers(
p, q, d, dp, dq, qi, public_numbers).private_key(
default_backend())
return cls(key=key)
def fields_to_partial_json(self):
# pylint: disable=protected-access
if isinstance(self.key._wrapped, rsa.RSAPublicKey):
numbers = self.key.public_numbers()
params = {
'n': numbers.n,
'e': numbers.e,
}
else: # rsa.RSAPrivateKey
private = self.key.private_numbers()
public = self.key.public_key().public_numbers()
params = {
'n': public.n,
'e': public.e,
'd': private.d,
'p': private.p,
'q': private.q,
'dp': private.dmp1,
'dq': private.dmq1,
'qi': private.iqmp,
}
return dict((key, self._encode_param(value))
for key, value in six.iteritems(params))