def from_private_bytes(cls, data):
from cryptography.hazmat.backends.openssl.backend import backend
if not backend.x25519_supported():
raise UnsupportedAlgorithm(
"X25519 is not supported by this version of OpenSSL.",
_Reasons.UNSUPPORTED_EXCHANGE_ALGORITHM)
return backend.x25519_load_private_bytes(data)
def from_private_bytes(cls, data):
from cryptography.hazmat.backends.openssl.backend import backend
if not backend.x25519_supported():
raise UnsupportedAlgorithm(
"X25519 is not supported by this version of OpenSSL.",
_Reasons.UNSUPPORTED_EXCHANGE_ALGORITHM
)
return backend.x25519_load_private_bytes(data)
def sk_to_curve25519(ed: ed25519.Ed25519PrivateKey) -> x25519.X25519PrivateKey:
raw = ed.private_bytes(
encoding=serialization.Encoding.Raw,
format=serialization.PrivateFormat.Raw,
encryption_algorithm=serialization.NoEncryption(),
)
# as proposed in https://github.com/pyca/cryptography/issues/5557#issuecomment-739339132
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.backends.openssl.backend import backend
hasher = hashes.Hash(hashes.SHA512())
hasher.update(raw)
h = bytearray(hasher.finalize())
# curve25519 clamping
h[0] &= 248
h[31] &= 127
h[31] |= 64
return backend.x25519_load_private_bytes(h[0:32])
def _from_private_bytes(cls, data):
from cryptography.hazmat.backends.openssl.backend import backend
return backend.x25519_load_private_bytes(data)
def _from_private_bytes(cls, data):
from cryptography.hazmat.backends.openssl.backend import backend
return backend.x25519_load_private_bytes(data)