gabriel / muse public
test_derived_key_zeroing.py python
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sha256:81ae324db5ad375fbfe4834c6fcb378312cafad3cc92dec5d3e5c427306621a2 fix: remove commit_exists filter from have anchors — server… Sonnet 4.6 patch 21 days ago
1 """Tests for DerivedKey memory zeroing after use.
2
3 DerivedKey.private_bytes and DerivedKey.chain_code used to be immutable
4 ``bytes`` — they could not be zeroed, so raw key material lingered in the
5 Python heap indefinitely after derivation.
6
7 Fix:
8 - Fields changed to ``bytearray`` so contents can be overwritten.
9 - ``DerivedKey.zero()`` sets both fields to all-zero bytes.
10 - ``derive_path`` zeroes each intermediate DerivedKey after deriving the
11 next child.
12 - ``derive_hd_public_info`` zeroes the final DerivedKey after the Ed25519
13 PrivateKey object has been created.
14
15 Coverage
16 --------
17 I DerivedKey fields are bytearray
18 I1 private_bytes is bytearray, not bytes
19 I2 chain_code is bytearray, not bytes
20
21 II DerivedKey.zero() wipes both fields
22 II1 after zero(), private_bytes is all-zero
23 II2 after zero(), chain_code is all-zero
24 II3 zero() does not affect the length (still 32 bytes)
25
26 III derive_hd_public_info zeroes the final DerivedKey
27 III1 private_bytes is all-zero in the DerivedKey after derive_hd_public_info returns
28 III2 chain_code is all-zero in the DerivedKey after derive_hd_public_info returns
29
30 IV Derivation still correct after zeroing changes
31 IV1 same seed → same fingerprint (deterministic derivation unchanged)
32 """
33
34 from __future__ import annotations
35
36 from unittest.mock import patch
37
38 import pytest
39
40 from muse.core import hdkeys as _hdkeys
41 from muse.core.slip010 import master_key, DerivedKey
42 from muse.core.bip39 import mnemonic_to_seed
43 from muse.core.keypair import derive_hd_public_info
44
45 _MNEMONIC = (
46 "abandon abandon abandon abandon abandon abandon abandon abandon "
47 "abandon abandon abandon about"
48 )
49 _SEED = mnemonic_to_seed(_MNEMONIC)
50
51
52
53
54 # ---------------------------------------------------------------------------
55 # I DerivedKey fields are bytearray
56 # ---------------------------------------------------------------------------
57
58 class TestDerivedKeyFieldTypes:
59 def test_I1_private_bytes_is_bytearray(self) -> None:
60 """I1: DerivedKey.private_bytes must be bytearray, not bytes."""
61 dk = master_key(_SEED)
62 assert isinstance(dk.private_bytes, bytearray), (
63 f"private_bytes must be bytearray, got {type(dk.private_bytes).__name__}"
64 )
65
66 def test_I2_chain_code_is_bytearray(self) -> None:
67 """I2: DerivedKey.chain_code must be bytearray, not bytes."""
68 dk = master_key(_SEED)
69 assert isinstance(dk.chain_code, bytearray), (
70 f"chain_code must be bytearray, got {type(dk.chain_code).__name__}"
71 )
72
73
74 # ---------------------------------------------------------------------------
75 # II DerivedKey.zero() wipes both fields
76 # ---------------------------------------------------------------------------
77
78 class TestDerivedKeyZero:
79 def test_II1_zero_wipes_private_bytes(self) -> None:
80 """II1: after zero(), private_bytes contains only null bytes."""
81 dk = master_key(_SEED)
82 assert any(b != 0 for b in dk.private_bytes), "pre-condition: key must not already be zero"
83 dk.zero()
84 assert dk.private_bytes == bytearray(32), "private_bytes must be all-zero after zero()"
85
86 def test_II2_zero_wipes_chain_code(self) -> None:
87 """II2: after zero(), chain_code contains only null bytes."""
88 dk = master_key(_SEED)
89 assert any(b != 0 for b in dk.chain_code), "pre-condition: chain_code must not already be zero"
90 dk.zero()
91 assert dk.chain_code == bytearray(32), "chain_code must be all-zero after zero()"
92
93 def test_II3_zero_preserves_length(self) -> None:
94 """II3: zero() does not change the field lengths."""
95 dk = master_key(_SEED)
96 dk.zero()
97 assert len(dk.private_bytes) == 32
98 assert len(dk.chain_code) == 32
99
100
101 # ---------------------------------------------------------------------------
102 # III derive_hd_public_info zeroes the final DerivedKey
103 # ---------------------------------------------------------------------------
104
105 class TestDeriveHdPublicInfoZeroing:
106 def test_III1_private_bytes_zeroed_after_derive(self) -> None:
107 """III1: the DerivedKey's private_bytes are all-zero after derive_hd_public_info."""
108 captured: list[DerivedKey] = []
109 original_derive = _hdkeys.derive_identity_key
110
111 def capturing_derive(*args: int | bytes, **kwargs: int) -> DerivedKey:
112 dk = original_derive(*args, **kwargs)
113 captured.append(dk)
114 return dk
115
116 with patch.object(_hdkeys, "derive_identity_key", side_effect=capturing_derive):
117 derive_hd_public_info(_SEED)
118
119 assert captured, "derive_identity_key was not called"
120 dk = captured[0]
121 assert dk.private_bytes == bytearray(32), (
122 "private_bytes must be zeroed after derive_hd_public_info"
123 )
124
125 def test_III2_chain_code_zeroed_after_derive(self) -> None:
126 """III2: the DerivedKey's chain_code is all-zero after derive_hd_public_info."""
127 captured: list[DerivedKey] = []
128 original_derive = _hdkeys.derive_identity_key
129
130 def capturing_derive(*args: int | bytes, **kwargs: int) -> DerivedKey:
131 dk = original_derive(*args, **kwargs)
132 captured.append(dk)
133 return dk
134
135 with patch.object(_hdkeys, "derive_identity_key", side_effect=capturing_derive):
136 derive_hd_public_info(_SEED)
137
138 dk = captured[0]
139 assert dk.chain_code == bytearray(32), (
140 "chain_code must be zeroed after derive_hd_public_info"
141 )
142
143
144 # ---------------------------------------------------------------------------
145 # IV Derivation still correct
146 # ---------------------------------------------------------------------------
147
148 class TestDerivedKeyZeroingCorrectness:
149 def test_IV1_same_seed_same_fingerprint(self) -> None:
150 """IV1: zeroing does not affect determinism — same seed → same fingerprint."""
151 _, fp1 = derive_hd_public_info(_SEED)
152 _, fp2 = derive_hd_public_info(_SEED)
153 assert fp1 == fp2, "Zeroing must not break deterministic derivation"
File History 4 commits
sha256:81ae324db5ad375fbfe4834c6fcb378312cafad3cc92dec5d3e5c427306621a2 fix: remove commit_exists filter from have anchors — server… Sonnet 4.6 patch 21 days ago
sha256:36c3cb3e76619d4c30a6d9bf81b5ec4ff148e30dcfed913e3114ca7b43b81c7e fix: rename objects→blobs in push client and all stale test… Sonnet 4.6 patch 22 days ago
sha256:c06a9b9b9fee26c68ea725b44d54b2c0a171301ce9de746d5b656617b4463a9a fix: repair four test failures from post-migration audit Sonnet 4.6 patch 29 days ago
sha256:1900655993c83c4107067375548a7be823e471d2515830842f1a12cba4bd3cdf fix: unified object store migration — idempotent writes, JS… Sonnet 4.6 minor ⚠ 29 days ago