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 = json_util.Field('alg',
decoder=jwa.JWASignature.from_json,
omitempty=True)
jku = json_util.Field('jku', omitempty=True)
jwk = json_util.Field('jwk', decoder=jwk.JWK.from_json, omitempty=True)
kid = json_util.Field('kid', omitempty=True)
x5u = json_util.Field('x5u', omitempty=True)
x5c = json_util.Field('x5c', omitempty=True, default=())
x5t = json_util.Field('x5t',
decoder=json_util.decode_b64jose,
omitempty=True)
x5tS256 = json_util.Field('x5t#S256',
decoder=json_util.decode_b64jose,
omitempty=True)
typ = json_util.Field('typ',
encoder=MediaType.encode,
decoder=MediaType.decode,
omitempty=True)
cty = json_util.Field('cty',
encoder=MediaType.encode,
decoder=MediaType.decode,
omitempty=True)
crit = json_util.Field('crit', omitempty=True, default=())
def not_omitted(self):
"""Fields that would not be omitted in the JSON object."""
return dict((name, getattr(self, name))
for name, field in six.iteritems(self._fields)
if not field.omit(getattr(self, name)))
def __add__(self, other):
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) # pylint: disable=star-args
def find_key(self):
"""Find key based on header.
.. todo:: Supports only "jwk" header parameter lookup.
:returns: (Public) key found in the header.
:rtype: :class:`acme.jose.jwk.JWK`
:raises acme.jose.errors.Error: if key could not be found
"""
if self.jwk is None:
raise errors.Error('No key found')
return self.jwk
@crit.decoder
def crit(unused_value):
# pylint: disable=missing-docstring,no-self-argument,no-self-use
raise errors.DeserializationError(
'"crit" is not supported, please subclass')
# x5c does NOT use JOSE Base64 (4.1.6)
@x5c.encoder
def x5c(value): # pylint: disable=missing-docstring,no-self-argument
return [
base64.b64encode(
OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_ASN1,
cert)) for cert in value
]
@x5c.decoder
def x5c(value): # pylint: disable=missing-docstring,no-self-argument
try:
return tuple(
util.ComparableX509(
OpenSSL.crypto.load_certificate(
OpenSSL.crypto.FILETYPE_ASN1, base64.b64decode(cert)))
for cert in value)
except OpenSSL.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
__slots__ = ('combined', )
protected = json_util.Field('protected', omitempty=True, default='')
header = json_util.Field('header',
omitempty=True,
default=header_cls(),
decoder=header_cls.from_json)
signature = json_util.Field('signature',
decoder=json_util.decode_b64jose,
encoder=json_util.encode_b64jose)
@protected.encoder
def protected(value): # pylint: disable=missing-docstring,no-self-argument
# wrong type guess (Signature, not bytes) | pylint: disable=no-member
return json_util.encode_b64jose(value.encode('utf-8'))
@protected.decoder
def protected(value): # pylint: disable=missing-docstring,no-self-argument
return json_util.decode_b64jose(value).decode('utf-8')
def __init__(self, **kwargs):
if 'combined' not in kwargs:
kwargs = self._with_combined(kwargs)
super(Signature, self).__init__(**kwargs)
assert self.combined.alg is not None
@classmethod
def _with_combined(cls, kwargs):
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, payload):
return (b64.b64encode(protected.encode('utf-8')) + b'.' +
b64.b64encode(payload))
def verify(self, payload, key=None):
"""Verify.
:param key: Key used for verification.
:type key: :class:`acme.jose.jwk.JWK`
"""
key = self.combined.find_key() if key is None else key
return self.combined.alg.verify(key=key.key,
sig=self.signature,
msg=self._msg(self.protected, payload))
@classmethod
def sign(cls,
payload,
key,
alg,
include_jwk=True,
protect=frozenset(),
**kwargs):
"""Sign.
:param key: Key for signature.
:type key: :class:`acme.jose.jwk.JWK`
"""
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:
protected_params[header] = header_params.pop(header)
if protected_params:
# pylint: disable=star-args
protected = cls.header_cls(**protected_params).json_dumps()
else:
protected = ''
header = cls.header_cls(**header_params) # pylint: disable=star-args
signature = alg.sign(key.key, cls._msg(protected, payload))
return cls(protected=protected, header=header, signature=signature)
def fields_to_partial_json(self):
fields = super(Signature, self).fields_to_partial_json()
if not fields['header'].not_omitted():
del fields['header']
return fields
@classmethod
def fields_from_json(cls, jobj):
fields = super(Signature, cls).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