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# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
from __future__ import absolute_import, division, print_function
from cryptography import utils
from cryptography.hazmat.backends.openssl.utils import _evp_pkey_derive
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric.x25519 import (
X25519PrivateKey,
X25519PublicKey,
)
_X25519_KEY_SIZE = 32
@utils.register_interface(X25519PublicKey)
class _X25519PublicKey(object):
def __init__(self, backend, evp_pkey):
self._backend = backend
self._evp_pkey = evp_pkey
def public_bytes(self, encoding, format):
if (
encoding is serialization.Encoding.Raw
or format is serialization.PublicFormat.Raw
):
if (
encoding is not serialization.Encoding.Raw
or format is not serialization.PublicFormat.Raw
):
raise ValueError(
"When using Raw both encoding and format must be Raw"
)
return self._raw_public_bytes()
return self._backend._public_key_bytes(
encoding, format, self, self._evp_pkey, None
)
def _raw_public_bytes(self):
ucharpp = self._backend._ffi.new("unsigned char **")
res = self._backend._lib.EVP_PKEY_get1_tls_encodedpoint(
self._evp_pkey, ucharpp
)
self._backend.openssl_assert(res == 32)
self._backend.openssl_assert(ucharpp[0] != self._backend._ffi.NULL)
data = self._backend._ffi.gc(
ucharpp[0], self._backend._lib.OPENSSL_free
)
return self._backend._ffi.buffer(data, res)[:]
@utils.register_interface(X25519PrivateKey)
class _X25519PrivateKey(object):
def __init__(self, backend, evp_pkey):
self._backend = backend
self._evp_pkey = evp_pkey
def public_key(self):
bio = self._backend._create_mem_bio_gc()
res = self._backend._lib.i2d_PUBKEY_bio(bio, self._evp_pkey)
self._backend.openssl_assert(res == 1)
evp_pkey = self._backend._lib.d2i_PUBKEY_bio(
bio, self._backend._ffi.NULL
)
self._backend.openssl_assert(evp_pkey != self._backend._ffi.NULL)
evp_pkey = self._backend._ffi.gc(
evp_pkey, self._backend._lib.EVP_PKEY_free
)
return _X25519PublicKey(self._backend, evp_pkey)
def exchange(self, peer_public_key):
if not isinstance(peer_public_key, X25519PublicKey):
raise TypeError("peer_public_key must be X25519PublicKey.")
return _evp_pkey_derive(self._backend, self._evp_pkey, peer_public_key)
def private_bytes(self, encoding, format, encryption_algorithm):
if (
encoding is serialization.Encoding.Raw
or format is serialization.PublicFormat.Raw
):
if (
format is not serialization.PrivateFormat.Raw
or encoding is not serialization.Encoding.Raw
or not isinstance(
encryption_algorithm, serialization.NoEncryption
)
):
raise ValueError(
"When using Raw both encoding and format must be Raw "
"and encryption_algorithm must be NoEncryption()"
)
return self._raw_private_bytes()
return self._backend._private_key_bytes(
encoding, format, encryption_algorithm, self, self._evp_pkey, None
)
def _raw_private_bytes(self):
# When we drop support for CRYPTOGRAPHY_OPENSSL_LESS_THAN_111 we can
# switch this to EVP_PKEY_new_raw_private_key
# The trick we use here is serializing to a PKCS8 key and just
# using the last 32 bytes, which is the key itself.
bio = self._backend._create_mem_bio_gc()
res = self._backend._lib.i2d_PKCS8PrivateKey_bio(
bio,
self._evp_pkey,
self._backend._ffi.NULL,
self._backend._ffi.NULL,
0,
self._backend._ffi.NULL,
self._backend._ffi.NULL,
)
self._backend.openssl_assert(res == 1)
pkcs8 = self._backend._read_mem_bio(bio)
self._backend.openssl_assert(len(pkcs8) == 48)
return pkcs8[-_X25519_KEY_SIZE:]
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