Files
DECNET/tests/canary/test_obfuscator.py
anti b26dd8f529 feat(canary): API-trashing defense — 4-layer fingerprint validation
Adds per-mint nonce gating, structural shape validation, mint UUID
consistency checks, and a per-(token, IP) rate limiter to the canary
worker so attackers who extract a canary from a decky filesystem cannot
poison fingerprint forensics by replaying or forging ?d= submissions.

Changes:

base.py
  fingerprint_nonce: Optional[str] added to CanaryArtifact so generators
  can surface the nonce to the cultivator without coupling the generator
  directly to DB code.

obfuscator.py
  nonce_for(callback_token, mint_uuid): HMAC-SHA256 keyed on
  DECNET_CANARY_FINGERPRINT_SECRET, truncated to 16 hex chars.
  FingerprintSecretMissing raised at mint time if env var is unset.
  render_fingerprint_js() now accepts nonce= and substitutes MINT_NONCE.

fingerprint_payload.js
  New MINT_NONCE placeholder. Appended as &k= on all beacon URLs (bare-open,
  single-shot, chunked). Using &k= avoids colliding with &n= (chunk total).

fingerprint_html.py / fingerprint_svg.py
  Derive nonce via nonce_for() and pass to render_fingerprint_js(). Set
  artifact.fingerprint_nonce so the cultivator can persist it.

cultivator.py
  Passes fingerprint_nonce into create_canary_token() when present on the
  artifact; NULL for all non-fingerprint generators.

canary.py (model)
  fingerprint_nonce: Optional[str] = Field(default=None, max_length=16)
  added to CanaryToken. None for non-fingerprint tokens.

worker.py
  _extract_fingerprint now returns (meta_dict, parsed_fp) tuple.
  _record_hit accepts parsed_fp + raw_nonce and runs 4 layers after
  token lookup: nonce match, shape check, mint UUID consistency, rate limit.
  Each failure sets _fp_invalid_* flag and drops structured _fp.
  Trigger row always lands regardless.

tests/canary/conftest.py
  Session-scoped autouse fixture sets DECNET_CANARY_FINGERPRINT_SECRET so
  fingerprint generator and worker tests work offline.

tests
  5 new worker HTTP tests and 2 new generator tests covering each
  validation layer.
2026-04-29 17:41:04 -04:00

105 lines
3.6 KiB
Python

"""Tests for :mod:`decnet.canary.obfuscator` — the per-mint JS obfuscator.
Skipped when Node or the vendored ``javascript-obfuscator`` package is
not available (CI without npm install, fresh checkouts). When the
toolchain is present we assert:
* determinism — same callback_token → byte-identical output
* per-mint uniqueness — different tokens → different output
* the rendered fingerprint embeds the mint UUID and beacon URL
ahead of obfuscation, so the obfuscator's string-array transform
can absorb them
* the output is non-empty and parses as JS via Node
"""
from __future__ import annotations
import shutil
import subprocess
from pathlib import Path
import pytest
from decnet.canary import obfuscator
def _toolchain_ready() -> bool:
if shutil.which(obfuscator._NODE_BIN) is None: # noqa: SLF001
return False
helper_dir = Path(obfuscator._HELPER).parent # noqa: SLF001
return (helper_dir / "node_modules" / "javascript-obfuscator").is_dir()
pytestmark = pytest.mark.skipif(
not _toolchain_ready(),
reason="node + javascript-obfuscator not installed under decnet/canary",
)
def test_obfuscate_is_deterministic_per_token() -> None:
src = "var x = 1; function hello() { return x + 2; } hello();"
a = obfuscator.obfuscate(src, callback_token="aaaa-bbbb")
b = obfuscator.obfuscate(src, callback_token="aaaa-bbbb")
assert a == b
assert a.strip()
def test_obfuscate_differs_across_tokens() -> None:
src = "var x = 1; function hello() { return x + 2; } hello();"
a = obfuscator.obfuscate(src, callback_token="aaaa-bbbb")
b = obfuscator.obfuscate(src, callback_token="cccc-dddd")
assert a != b
def test_render_fingerprint_js_substitutes_then_obfuscates() -> None:
out = obfuscator.render_fingerprint_js(
callback_token="tok-12345",
http_base="https://canary.example.test",
mint_uuid="11111111-2222-3333-4444-555555555555",
nonce="deadbeef01234567",
)
# Template placeholders must NOT survive into the output.
assert "{{BEACON_URL}}" not in out
assert "{{MINT_UUID}}" not in out
assert "{{MINT_NONCE}}" not in out
assert out.strip()
# Should be syntactically valid JS — Node parses it without throwing.
proc = subprocess.run(
[obfuscator._NODE_BIN, "--check", "-"], # noqa: SLF001
input=out, capture_output=True, text=True,
timeout=15, check=False,
)
assert proc.returncode == 0, proc.stderr
def test_render_fingerprint_js_is_deterministic() -> None:
kw = dict(
callback_token="tok-12345",
http_base="https://canary.example.test",
mint_uuid="11111111-2222-3333-4444-555555555555",
nonce="deadbeef01234567",
)
a = obfuscator.render_fingerprint_js(**kw)
b = obfuscator.render_fingerprint_js(**kw)
assert a == b
def test_seed_from_token_is_31bit_positive() -> None:
seed = obfuscator._seed_from_token("anything") # noqa: SLF001
assert 0 <= seed <= 0x7FFFFFFF
def test_config_from_seed_is_pure_function() -> None:
cfg_a = obfuscator._config_from_seed(12345) # noqa: SLF001
cfg_b = obfuscator._config_from_seed(12345) # noqa: SLF001
assert cfg_a == cfg_b
assert cfg_a["seed"] == 12345
# Sanity: the stable knobs we never randomize are present.
assert cfg_a["stringArray"] is True
assert cfg_a["controlFlowFlattening"] is True
def test_obfuscator_error_on_bad_node_bin(monkeypatch: pytest.MonkeyPatch) -> None:
monkeypatch.setattr(obfuscator, "_NODE_BIN", "/nonexistent/node-binary-xyz")
with pytest.raises(obfuscator.ObfuscatorError):
obfuscator.obfuscate("var x=1;", callback_token="t")