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"""
Copyright (c) 2023 Proton AG
This file is part of Proton VPN.
Proton VPN is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Proton VPN is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with ProtonVPN. If not, see <https://www.gnu.org/licenses/>.
"""
import base64
import hashlib
from typing import Optional
import cryptography.hazmat.primitives.asymmetric
from cryptography.hazmat.primitives.serialization import Encoding, PrivateFormat
from cryptography.hazmat.primitives import serialization
import nacl.bindings
class KeyHandler: # pylint: disable=missing-class-docstring
PREFIX_SK = bytes(
[int(x, 16) for x in '30:2E:02:01:00:30:05:06:03:2B:65:70:04:22:04:20'.split(':')]
)
PREFIX_PK = bytes([int(x, 16) for x in '30:2A:30:05:06:03:2B:65:70:03:21:00'.split(':')])
def __init__(self, private_key=None):
""" private key parameter must be in ed25519 format,
from which we convert to x25519 format with nacl.
But it's not possible to convert from x25519 to ed25519.
"""
self._private_key, self._public_key = self.__generate_key_pair(private_key=private_key)
tmp_ed25519_sk = self.ed25519_sk_bytes
tmp_ed25519_pk = self.ed25519_pk_bytes
"""
# crypto_sign_ed25519_sk_to_curve25519() is equivalent to :
tmp = list(hashlib.sha512(ed25519_sk).digest()[:32])
tmp[0] &= 248
tmp[31] &= 127
tmp[31] |= 64
self._x25519_sk = bytes(tmp)
"""
self._x25519_sk = nacl.bindings.crypto_sign_ed25519_sk_to_curve25519(
tmp_ed25519_sk + tmp_ed25519_pk
)
self._x25519_pk = nacl.bindings.crypto_sign_ed25519_pk_to_curve25519(tmp_ed25519_pk)
@classmethod
def get_proton_fingerprint_from_x25519_pk(cls, x25519_pk: bytes) -> str: # noqa: E501 pylint: disable=missing-function-docstring
return base64.b64encode(hashlib.sha512(x25519_pk).digest()).decode("ascii")
@classmethod
def from_sk_file(cls, ed25519sk_file): # pylint: disable=missing-function-docstring
backend_default = None
# cryptography.sys.version_info not available in 2.6
crypto_major, crypto_minor = cryptography.__version__.split(".")[:2]
if int(crypto_major) < 3 or \
int(crypto_major) == 3 and \
int(crypto_minor) < 1:
# backend is required if library < 3.1
backend_default = cryptography.hazmat.backends.default_backend()
with open(file=ed25519sk_file) as file: # pylint: disable=unspecified-encoding
pem_data = "".join(file.readlines())
key = serialization.load_pem_private_key(
pem_data.encode("ascii"), password=None, backend=backend_default
)
assert isinstance( # nosec B311, B101 # noqa: E501 # pylint: disable=line-too-long # nosemgrep: gitlab.bandit.B101
key,
cryptography.hazmat.primitives.asymmetric.ed25519.Ed25519PrivateKey) # nosec: B101
private_key = key.private_bytes(
Encoding.Raw, PrivateFormat.Raw,
encryption_algorithm=serialization.NoEncryption()
)
return KeyHandler(private_key=private_key)
@property
def ed25519_sk_str(self) -> str: # pylint: disable=missing-function-docstring
return base64.b64encode(self.ed25519_sk_bytes).decode("ascii")
@property
def ed25519_sk_bytes(self) -> bytes: # pylint: disable=missing-function-docstring
return self._private_key.private_bytes(
Encoding.Raw, PrivateFormat.Raw,
encryption_algorithm=serialization.NoEncryption()
)
@property
def ed25519_pk_bytes(self) -> bytes: # pylint: disable=missing-function-docstring
return self._public_key.public_bytes(
encoding=serialization.Encoding.Raw,
format=serialization.PublicFormat.Raw
)
@property
def ed25519_pk_str_asn1(self) -> bytes: # pylint: disable=missing-function-docstring
return base64.b64encode(self.PREFIX_PK + self.ed25519_pk_bytes)
@property
def ed25519_sk_pem(self) -> str: # pylint: disable=missing-function-docstring
return self.get_ed25519_sk_pem()
@property
def ed25519_pk_pem(self) -> str: # pylint: disable=missing-function-docstring
return self._public_key.public_bytes(
encoding=serialization.Encoding.PEM,
format=serialization.PublicFormat.SubjectPublicKeyInfo
).decode('ascii')
@property
def x25519_sk_bytes(self) -> bytes: # pylint: disable=missing-function-docstring
return self._x25519_sk
@property
def x25519_pk_bytes(self) -> bytes: # pylint: disable=missing-function-docstring
return self._x25519_pk
@property
def x25519_sk_str(self) -> str: # pylint: disable=missing-function-docstring
return base64.b64encode(self._x25519_sk).decode("ascii")
@property
def x25519_pk_str(self) -> str: # pylint: disable=missing-function-docstring
return base64.b64encode(self._x25519_pk).decode("ascii")
@classmethod
def __generate_key_pair(cls, private_key=None):
if private_key:
private_key = cryptography.hazmat.primitives.asymmetric\
.ed25519.Ed25519PrivateKey.from_private_bytes(private_key)
else:
private_key = cryptography.hazmat.primitives.asymmetric\
.ed25519.Ed25519PrivateKey.generate()
public_key = private_key.public_key()
return private_key, public_key
def get_ed25519_sk_pem(self, password: Optional[bytes] = None) -> str:
"""
Returns the ed5519 private key in pem format,
and encrypted if a password was passed.
"""
if password:
encryption_algorithm = serialization.BestAvailableEncryption(password=password)
else:
encryption_algorithm = serialization.NoEncryption()
return self._private_key.private_bytes(
encoding=Encoding.PEM, format=PrivateFormat.PKCS8,
encryption_algorithm=encryption_algorithm
).decode('ascii')
def bytes_to_str_hexa(b: bytes): # pylint: disable=missing-function-docstring invalid-name
return ":".join(["{:02x}".format(x) for x in b]) # pylint: disable=consider-using-f-string
|
