def pk_to_curve25519(ed: ed25519.Ed25519PublicKey) -> x25519.X25519PublicKey:
raw = ed.public_bytes(
encoding=serialization.Encoding.Raw,
format=serialization.PublicFormat.Raw,
)
# This is libsodium's crypto_sign_ed25519_pk_to_curve25519 translated into
# the Pyton module ge25519.
from ge25519 import ge25519, ge25519_p3
from fe25519 import fe25519
if ge25519.has_small_order(raw) != 0:
raise RuntimeError("Doesn' thave small order")
# frombytes in libsodium appears to be the same as
# frombytes_negate_vartime; as ge25519 only implements the from_bytes
# version, we have to do the root check manually.
A = ge25519_p3.from_bytes(raw)
if A.root_check:
raise RuntimeError("Root check failed")
if not A.is_on_main_subgroup():
raise RuntimeError("It's on the main subgroup")
one_minus_y = fe25519.one() - A.Y
x = A.Y + fe25519.one()
x = x * one_minus_y.invert()
return x25519.X25519PublicKey.from_public_bytes(bytes(x.to_bytes()))
def encode_public(
self, public_key: ed25519.Ed25519PublicKey, f_pub: _FragList
) -> None:
"""Write Ed25519 public key"""
raw_public_key = public_key.public_bytes(
Encoding.Raw, PublicFormat.Raw
)
f_pub.put_sshstr(raw_public_key)
def pk_to_curve25519(ed: ed25519.Ed25519PublicKey) -> x25519.X25519PublicKey:
raw = ed.public_bytes(
encoding=serialization.Encoding.Raw,
format=serialization.PublicFormat.Raw,
)
ed_nacl = nacl.signing.VerifyKey(key=raw, )
x_nacl = ed_nacl.to_curve25519_public_key()
return x25519.X25519PublicKey.from_public_bytes(x_nacl.encode())
def public_key_to_bytes(public_key: Ed25519PublicKey) -> bytes:
"""Returns the raw hex encoded bytes of a Ed25519PublicKey.
Args:
public_key (Ed25519PublicKey): Public key to encode.
Returns:
bytes: Byte encoding.
"""
return public_key.public_bytes(serialization.Encoding.Raw,
serialization.PublicFormat.Raw)
def public_key_bytes(public_key: Ed25519PublicKey) -> bytes:
"""convert cryptography.hazmat.primitives.asymmetric.ed25519.Ed25519PublicKey into raw bytes"""
return public_key.public_bytes(encoding=serialization.Encoding.Raw,
format=serialization.PublicFormat.Raw)
