diff options
Diffstat (limited to 'src/cryptography/hazmat/primitives/kdf')
| -rw-r--r-- | src/cryptography/hazmat/primitives/kdf/__init__.py | 14 | ||||
| -rw-r--r-- | src/cryptography/hazmat/primitives/kdf/hkdf.py | 124 | ||||
| -rw-r--r-- | src/cryptography/hazmat/primitives/kdf/pbkdf2.py | 66 |
3 files changed, 204 insertions, 0 deletions
diff --git a/src/cryptography/hazmat/primitives/kdf/__init__.py b/src/cryptography/hazmat/primitives/kdf/__init__.py new file mode 100644 index 00000000..2f420574 --- /dev/null +++ b/src/cryptography/hazmat/primitives/kdf/__init__.py @@ -0,0 +1,14 @@ +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or +# implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +from __future__ import absolute_import, division, print_function diff --git a/src/cryptography/hazmat/primitives/kdf/hkdf.py b/src/cryptography/hazmat/primitives/kdf/hkdf.py new file mode 100644 index 00000000..04d02b26 --- /dev/null +++ b/src/cryptography/hazmat/primitives/kdf/hkdf.py @@ -0,0 +1,124 @@ +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or +# implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +from __future__ import absolute_import, division, print_function + +import six + +from cryptography import utils +from cryptography.exceptions import ( + AlreadyFinalized, InvalidKey, UnsupportedAlgorithm, _Reasons +) +from cryptography.hazmat.backends.interfaces import HMACBackend +from cryptography.hazmat.primitives import constant_time, hmac, interfaces + + +@utils.register_interface(interfaces.KeyDerivationFunction) +class HKDF(object): + def __init__(self, algorithm, length, salt, info, backend): + if not isinstance(backend, HMACBackend): + raise UnsupportedAlgorithm( + "Backend object does not implement HMACBackend.", + _Reasons.BACKEND_MISSING_INTERFACE + ) + + self._algorithm = algorithm + + if not isinstance(salt, bytes) and salt is not None: + raise TypeError("salt must be bytes.") + + if salt is None: + salt = b"\x00" * (self._algorithm.digest_size // 8) + + self._salt = salt + + self._backend = backend + + self._hkdf_expand = HKDFExpand(self._algorithm, length, info, backend) + + def _extract(self, key_material): + h = hmac.HMAC(self._salt, self._algorithm, backend=self._backend) + h.update(key_material) + return h.finalize() + + def derive(self, key_material): + if not isinstance(key_material, bytes): + raise TypeError("key_material must be bytes.") + + return self._hkdf_expand.derive(self._extract(key_material)) + + def verify(self, key_material, expected_key): + if not constant_time.bytes_eq(self.derive(key_material), expected_key): + raise InvalidKey + + +@utils.register_interface(interfaces.KeyDerivationFunction) +class HKDFExpand(object): + def __init__(self, algorithm, length, info, backend): + if not isinstance(backend, HMACBackend): + raise UnsupportedAlgorithm( + "Backend object does not implement HMACBackend.", + _Reasons.BACKEND_MISSING_INTERFACE + ) + + self._algorithm = algorithm + + self._backend = backend + + max_length = 255 * (algorithm.digest_size // 8) + + if length > max_length: + raise ValueError( + "Can not derive keys larger than {0} octets.".format( + max_length + )) + + self._length = length + + if not isinstance(info, bytes) and info is not None: + raise TypeError("info must be bytes.") + + if info is None: + info = b"" + + self._info = info + + self._used = False + + def _expand(self, key_material): + output = [b""] + counter = 1 + + while (self._algorithm.digest_size // 8) * len(output) < self._length: + h = hmac.HMAC(key_material, self._algorithm, backend=self._backend) + h.update(output[-1]) + h.update(self._info) + h.update(six.int2byte(counter)) + output.append(h.finalize()) + counter += 1 + + return b"".join(output)[:self._length] + + def derive(self, key_material): + if not isinstance(key_material, bytes): + raise TypeError("key_material must be bytes.") + + if self._used: + raise AlreadyFinalized + + self._used = True + return self._expand(key_material) + + def verify(self, key_material, expected_key): + if not constant_time.bytes_eq(self.derive(key_material), expected_key): + raise InvalidKey diff --git a/src/cryptography/hazmat/primitives/kdf/pbkdf2.py b/src/cryptography/hazmat/primitives/kdf/pbkdf2.py new file mode 100644 index 00000000..97b6408c --- /dev/null +++ b/src/cryptography/hazmat/primitives/kdf/pbkdf2.py @@ -0,0 +1,66 @@ +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or +# implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +from __future__ import absolute_import, division, print_function + +from cryptography import utils +from cryptography.exceptions import ( + AlreadyFinalized, InvalidKey, UnsupportedAlgorithm, _Reasons +) +from cryptography.hazmat.backends.interfaces import PBKDF2HMACBackend +from cryptography.hazmat.primitives import constant_time, interfaces + + +@utils.register_interface(interfaces.KeyDerivationFunction) +class PBKDF2HMAC(object): + def __init__(self, algorithm, length, salt, iterations, backend): + if not isinstance(backend, PBKDF2HMACBackend): + raise UnsupportedAlgorithm( + "Backend object does not implement PBKDF2HMACBackend.", + _Reasons.BACKEND_MISSING_INTERFACE + ) + + if not backend.pbkdf2_hmac_supported(algorithm): + raise UnsupportedAlgorithm( + "{0} is not supported for PBKDF2 by this backend.".format( + algorithm.name), + _Reasons.UNSUPPORTED_HASH + ) + self._used = False + self._algorithm = algorithm + self._length = length + if not isinstance(salt, bytes): + raise TypeError("salt must be bytes.") + self._salt = salt + self._iterations = iterations + self._backend = backend + + def derive(self, key_material): + if self._used: + raise AlreadyFinalized("PBKDF2 instances can only be used once.") + self._used = True + + if not isinstance(key_material, bytes): + raise TypeError("key_material must be bytes.") + return self._backend.derive_pbkdf2_hmac( + self._algorithm, + self._length, + self._salt, + self._iterations, + key_material + ) + + def verify(self, key_material, expected_key): + derived_key = self.derive(key_material) + if not constant_time.bytes_eq(derived_key, expected_key): + raise InvalidKey("Keys do not match.") |