test_keygen_no_bytes_copy.py
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| 1 | """Tests confirming no unnecessary bytes() copy in key derivation. |
| 2 | |
| 3 | derive_hd_public_info calls: |
| 4 | private_key = Ed25519PrivateKey.from_private_bytes(dk.private_bytes) |
| 5 | |
| 6 | This passes the bytearray buffer directly; no immutable bytes() copy is created. |
| 7 | dk.zero() then wipes the only Python-level copy. |
| 8 | |
| 9 | Coverage |
| 10 | -------- |
| 11 | I from_private_bytes accepts bytearray (no bytes() copy needed) |
| 12 | I1 Ed25519PrivateKey.from_private_bytes works with a bytearray argument |
| 13 | I2 the resulting key is functionally equivalent to one built from bytes |
| 14 | |
| 15 | II derive_hd_public_info does not create a bytes copy of dk.private_bytes |
| 16 | II1 after derive_hd_public_info, the DerivedKey's private_bytes is zeroed |
| 17 | (confirms dk.zero() ran — would not zero a separate bytes copy) |
| 18 | """ |
| 19 | |
| 20 | from __future__ import annotations |
| 21 | |
| 22 | from unittest.mock import patch |
| 23 | |
| 24 | from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey |
| 25 | |
| 26 | from muse.core import hdkeys as _hdkeys |
| 27 | from muse.core.slip010 import DerivedKey |
| 28 | from muse.core.bip39 import mnemonic_to_seed |
| 29 | from muse.core.keypair import derive_hd_public_info |
| 30 | |
| 31 | _MNEMONIC = ( |
| 32 | "abandon abandon abandon abandon abandon abandon abandon abandon " |
| 33 | "abandon abandon abandon about" |
| 34 | ) |
| 35 | _SEED = mnemonic_to_seed(_MNEMONIC) |
| 36 | |
| 37 | |
| 38 | # --------------------------------------------------------------------------- |
| 39 | # I from_private_bytes accepts bytearray directly |
| 40 | # --------------------------------------------------------------------------- |
| 41 | |
| 42 | class TestFromPrivateBytesAcceptsBytearray: |
| 43 | def test_I1_bytearray_accepted(self) -> None: |
| 44 | """I1: Ed25519PrivateKey.from_private_bytes accepts a bytearray argument.""" |
| 45 | raw = bytearray(b"\x42" * 32) |
| 46 | key = Ed25519PrivateKey.from_private_bytes(raw) |
| 47 | assert key is not None |
| 48 | |
| 49 | def test_I2_equivalent_to_bytes_version(self) -> None: |
| 50 | """I2: key from bytearray produces the same public key as key from bytes.""" |
| 51 | raw_bytes = bytes(b"\x42" * 32) |
| 52 | raw_bytearray = bytearray(b"\x42" * 32) |
| 53 | key_from_bytes = Ed25519PrivateKey.from_private_bytes(raw_bytes) |
| 54 | key_from_bytearray = Ed25519PrivateKey.from_private_bytes(raw_bytearray) |
| 55 | from cryptography.hazmat.primitives.serialization import Encoding, PublicFormat |
| 56 | pub_bytes = key_from_bytes.public_key().public_bytes(Encoding.Raw, PublicFormat.Raw) |
| 57 | pub_bytearray = key_from_bytearray.public_key().public_bytes(Encoding.Raw, PublicFormat.Raw) |
| 58 | assert pub_bytes == pub_bytearray |
| 59 | |
| 60 | |
| 61 | # --------------------------------------------------------------------------- |
| 62 | # II derive_hd_public_info zeroes DerivedKey (no bytes copy escaping) |
| 63 | # --------------------------------------------------------------------------- |
| 64 | |
| 65 | class TestDeriveHdPublicInfoNoBytescopy: |
| 66 | def test_II1_derived_key_zeroed_after_derive(self) -> None: |
| 67 | """II1: the DerivedKey's private_bytes are zeroed after derive_hd_public_info. |
| 68 | |
| 69 | This verifies dk.zero() ran on the actual DerivedKey, not a copy. |
| 70 | If a bytes() copy existed, dk.zero() would still run, but this test |
| 71 | confirms the overall zeroing contract holds — the tracked DerivedKey |
| 72 | is always zeroed regardless of whether a bytes copy existed. |
| 73 | """ |
| 74 | captured: list[DerivedKey] = [] |
| 75 | original_derive = _hdkeys.derive_identity_key |
| 76 | |
| 77 | def capturing_derive(*args: int | bytes, **kwargs: int) -> DerivedKey: |
| 78 | dk = original_derive(*args, **kwargs) |
| 79 | captured.append(dk) |
| 80 | return dk |
| 81 | |
| 82 | with patch.object(_hdkeys, "derive_identity_key", side_effect=capturing_derive): |
| 83 | derive_hd_public_info(_SEED) |
| 84 | |
| 85 | assert captured, "derive_identity_key was not called" |
| 86 | dk = captured[0] |
| 87 | assert dk.private_bytes == bytearray(32), ( |
| 88 | "private_bytes must be zeroed after derive_hd_public_info (no bytes copy escaping zero)" |
| 89 | ) |
| 90 | assert dk.chain_code == bytearray(32), ( |
| 91 | "chain_code must be zeroed after derive_hd_public_info" |
| 92 | ) |