HSMAUTH: Fix public key data format for calculate session keys cmd

yubikit/hsmauth.py

@@ -48,6 +48,7 @@
 from enum import IntEnum, unique
 from dataclasses import dataclass
 from typing import Optional, List, Union, Tuple
+import struct
 
 import logging
 
@@ -106,7 +107,7 @@ def key_len(self):
  @property
  def pubkey_len(self):
  if self.name.startswith("EC_P256"):
- return 65
+ return 64
 
 
 def _parse_credential_password(credential_password: bytes) -> bytes:
@@ -467,7 +468,7 @@ def calculate_session_keys_asymmetric(
  self,
  label: str,
  context: bytes,
- public_key: ec.EllipticCurvePublicKeyWithSerialization,
+ public_key: ec.EllipticCurvePublicKey,
  credential_password: bytes,
  card_crypto: bytes,
  ) -> SessionKeys:
@@ -477,16 +478,21 @@ def calculate_session_keys_asymmetric(
  if not isinstance(public_key.curve, ec.SECP256R1):
  raise ValueError("Unsupported curve")
 
- ln = ALGORITHM.EC_P256_YUBICO_AUTHENTICATION
  numbers = public_key.public_numbers()
 
+ public_key_data = (
+ struct.pack("!B", 4)
+ + int.to_bytes(numbers.x, public_key.key_size // 8, "big")
+ + int.to_bytes(numbers.y, public_key.key_size // 8, "big")
+ )
+
  return SessionKeys.parse(
  self._calculate_session_keys(
- label,
- context,
- card_crypto,
- int2bytes((numbers.x + numbers.y), ln),
- credential_password,
+ label=label,
+ context=context,
+ credential_password=credential_password,
+ card_crypto=card_crypto,
+ public_key=public_key_data,
  )
  )