Files
TOIFAS/code/check_consistency.py
T
KiHoLee 138897aa8d Ship the learned-key pipeline, without which six figures cannot be rebuilt
The package was missing every script behind the KM (lrn.) curves and
both learned table rows: exp_learned's driver, the merge that folds the
learned rows into sec_compare.csv and refresh_summary.csv, and the
report that reads the learned numbers back. It was also missing
sec_keylen_perm.csv, so Fig. 3 could not be regenerated at all, and the
two diagnostics that answer why a fixed key beats a learned one here and
where a learned mask would win instead.

The learned artifacts themselves are regenerated. They were trained on
the cross-entropy alone, which drifts to disjoint sparse supports: 99
percent of each key's energy on about six of the 64 entries, so a digit
is decided over a sixth of its period and the key set is a choice of
support rather than a dense direction in R^L. They are now the
regularized keys of Section V-C, and check_consistency asserts which of
the two families the figures draw.

Verified from inside this repository: replot_security.py rebuilds all
seven result figures, make_tables.py reproduces both result tables, and
check_consistency.py passes every check that does not need the
manuscript.

The README now lists what ships. Its run list, layout and figure map had
none of the learned pipeline, named two tables the manuscript renders as
prose, and gave Fig. 3 no data file for its permutation curve.
2026-08-28 23:58:01 +09:00

452 lines
20 KiB
Python

# -*- coding: utf-8 -*-
"""Final consistency check: every headline number vs its raw CSV.
A quoted value that goes stale during a revision is the failure mode this
guards against, so each assertion recomputes from data/ rather than from
another quoted value. The manuscript-side assertions are skipped when
main.tex is absent, which is the case in the reproducibility package.
"""
import csv
import math
import re
from pathlib import Path
base = Path(__file__).resolve().parents[1]
_tex_path = base / "main.tex"
HAVE_TEX = _tex_path.exists()
tex = _tex_path.read_text(encoding="utf-8") if HAVE_TEX else ""
def rows(name):
with open(base / "data" / name) as f:
return list(csv.DictReader(f))
def col(name, k):
return [float(r[k]) for r in rows(name) if r[k] != "nan"]
ok = True
def chk(label, cond, detail, needs_tex=False):
global ok
if needs_tex and not HAVE_TEX:
print(" SKIP " + label + " :: main.tex not in this package")
return
print((" PASS " if cond else " FAIL ") + label + " :: " + detail)
if not cond:
ok = False
print("headline numbers vs raw data")
# --- Fig. 2: the proposal is below OMA -------------------------------
sn = rows("sec_snr.csv")
lg = [float(x["legit"]) for x in sn]
om = [float(x["oma"]) for x in sn]
rel = [(a - b) / b * 100 for a, b in zip(lg, om)]
chk("legit below OMA at every SNR", max(rel) < 0, "max relative %+.2f%%" % max(rel))
chk("gain 24 to 35 percent",
round(-max(rel)) == 24 and round(-min(rel)) == 35,
"%.2f to %.2f percent" % (-max(rel), -min(rel)))
chk("24 and 35 in tex", "$24$ to\n$35$~percent" in tex or "$24$ to $35$~percent" in tex,
"searched tex", needs_tex=True)
ew = [float(x["eve_wrong"]) for x in sn]
ch = float(sn[0]["chance"])
dev = max(abs(x - ch) for x in ew)
_ewl = [float(x["eve_wrong"]) for x in rows("sec_snr_learned.csv")]
dev = max(dev, max(abs(x - ch) for x in _ewl))
chk("outsider at chance to 4e-4, both families", dev < 4.0e-4,
"max deviation %.2e" % dev)
chk("4e-4 in tex", "$4\\times10^{-4}$" in tex, "searched tex",
needs_tex=True)
# the main configuration's legitimate rate, the reference every later
# assertion compares against; taken from the curve the main
# configuration produced rather than looked up by key length
MAIN_LEGIT = [float(x["legit"]) for x in sn if float(x["snr_db"]) == 10][0]
chk("main legitimate 0.053", round(MAIN_LEGIT, 3) == 0.053,
"%.4f" % MAIN_LEGIT)
# --- Fig. 3: key-length ratio ----------------------------------------
k = rows("sec_keylen.csv")
r64 = [x for x in k if int(x["L"]) == 64][0]
ratio = float(r64["oma"]) / float(r64["legit_ser"])
chk("key-length ratio 1.52", round(ratio, 2) == 1.52, "%.4f" % ratio)
chk("1.52 in tex", tex.count("1.52") >= 1, "%d occurrences" % tex.count("1.52"),
needs_tex=True)
chk("keys exactly orthogonal in the sweep",
max(float(x["mask_xcorr"]) for x in k) < 1e-6,
"max xcorr %.2e" % max(float(x["mask_xcorr"]) for x in k))
# --- Fig. 4: jamming --------------------------------------------------
g = col("sec_jam_gap.csv", "gap_db")
chk("gap 10.1-11.1 dB", round(min(g), 1) == 10.1 and round(max(g), 1) == 11.1,
"%.3f to %.3f" % (min(g), max(g)))
lin = (10 ** (min(g) / 10), 10 ** (max(g) / 10))
chk("more than ten times power", lin[0] > 10.0, "%.2f to %.2f" % lin)
j = rows("sec_jam_cmp.csv")
dmax = max(abs(float(r["blind"]) - float(r["perm_blind"])) for r in j)
chk("within 0.002", dmax <= 0.002, "%.5f" % dmax)
chk("no stale 8.1 dB", "$8.1$~dB" not in tex, "searched tex", needs_tex=True)
# --- Fig. 6: brute force ---------------------------------------------
b = rows("sec_brute_cmp.csv")
sm = float(b[-1]["ser_mask"])
chk("brute 0.67 at 1e6", round(sm, 2) == 0.67, "%.4f" % sm)
chk("0.67 in tex", "$0.67$" in tex, "searched tex", needs_tex=True)
closed = (ch - sm) / (ch - MAIN_LEGIT)
chk("brute closes about a third", 0.30 < closed < 0.40, "%.3f" % closed)
bf = float(b[-1]["best_frac"]) * 100
chk("permutation 3.4 percent of positions", round(bf, 1) == 3.4, "%.2f" % bf)
pad0 = next((x["K"] for x in b if float(x["ser_pad"]) < 0.1), None)
chk("index cipher collapses at 65536", pad0 == "65536", str(pad0))
# --- Fig. 7: known plaintext -----------------------------------------
kp = rows("kpa.csv")
legit = MAIN_LEGIT
thr = legit * 1.02
first20 = next((x["n_frames"] for x in kp
if int(x["snr_db"]) == 20 and float(x["eve_ser"]) <= thr), None)
first10 = next((x["n_frames"] for x in kp
if int(x["snr_db"]) == 10 and float(x["eve_ser"]) <= thr), None)
chk("KPA three frames at 20 dB", first20 == "3", "first N = %s" % first20)
chk("KPA ten frames at 10 dB", first10 == "10", "first N = %s" % first10)
kp0 = [x for x in kp if int(x["snr_db"]) == 0]
w0 = float(kp0[-1]["eve_ser"]) / legit
chk("0 dB no longer holds", w0 < 1.03, "64 frames reach %.3f of legitimate" % w0)
pk = rows("pkpa.csv")
p6 = float([x for x in pk if x["n_frames"] == "6"][0]["eve_ser"])
chk("perm KPA at N=6 near its own legitimate",
abs(p6 - MAIN_LEGIT) < 0.005, "%.4f" % p6)
# --- refresh ----------------------------------------------------------
rs = {x["scheme"]: x for x in rows("refresh_summary.csv")}
chk("refresh 364.6 bits",
round(float(rs["Invariant, KM (str.)"]["entropy_bits"]), 1) == 364.6,
"%.3f" % float(rs["Invariant, KM (str.)"]["entropy_bits"]))
chk("fixed key 23.8 bits",
round(float(rs["None (fixed key)"]["entropy_bits"]), 1) == 23.8,
"%.4f" % float(rs["None (fixed key)"]["entropy_bits"]))
chk("invariant refresh free",
abs(float(rs["Invariant, KM (str.)"]["legit"]) - float(rs["None (fixed key)"]["legit"]))
< 0.001, "%.4f vs %.4f" % (float(rs["Invariant, KM (str.)"]["legit"]),
float(rs["None (fixed key)"]["legit"])))
# --- real tokens ------------------------------------------------------
import json
st = json.loads((base / "data" / "real_sec_stats.json").read_text())
rec = st["recovery"]["28"]
chk("headline recovery 96 vs 93 percent",
round(rec["legit"] * 100) == 96 and round(rec["oma"] * 100) == 93,
"%.1f vs %.1f" % (rec["legit"] * 100, rec["oma"] * 100))
chk("legit leads OMA at every point",
all(st["recovery"][s]["legit"] > st["recovery"][s]["oma"]
for s in st["recovery"]),
"checked %d points" % len(st["recovery"]))
# --- the room argument of Fig. 2 and its evidence in Fig. 3 -----------
kl = {int(r["L"]): r for r in rows("sec_keylen.csv")}
r8 = kl[8]
chk("L=8 crowding, proposal behind OMA",
round(float(r8["legit_ser"]), 3) == 0.949
and round(float(r8["oma"]), 3) == 0.685,
"%.3f vs %.3f" % (float(r8["legit_ser"]), float(r8["oma"])))
chk("0.949 and 0.685 in tex", "0.949" in tex and "0.685" in tex,
"searched tex", needs_tex=True)
# the OMA-to-proposed ratio the narration quotes
sr = rows("sec_snr.csv")
rt = [float(r["oma"]) / float(r["legit"]) for r in sr]
chk("ratio spans 1.32 to 1.54", round(min(rt), 2) == 1.32
and round(max(rt), 2) == 1.54, "%.3f to %.3f" % (min(rt), max(rt)))
# the three secrets named in the setup
chk("secret sizes: per-user direction, perm 256, pad 16",
all(t in tex for t in ["length-$64$ key direction per user",
"one permutation of $256$",
"$16$ pad bits per user"]),
"searched tex", needs_tex=True)
chk("no stale d=64 configuration in tex",
"$d=64$ real dimensions" not in tex and "$d/U=16$" not in tex,
"searched tex", needs_tex=True)
# Fig. 5 shows the permutation curve tracking the mask curve
sc = rows("sec_sens_cmp.csv")
dv = max(abs(float(r["ser_mask"]) - float(r["ser_perm"])) for r in sc)
chk("permutation tracks mask in Fig. 5", dv < 0.06, "max gap %.3f" % dv)
# --- the audit round's corrected quantities ---------------------------
mf = {r["family"]: r for r in rows("sec_maskfam.csv")}
fam_pct = (float(mf["random"]["legit_ser"])
/ float(mf["hadamard"]["legit_ser"]) - 1) * 100
chk("continuous family 29 percent worse", round(fam_pct) == 29,
"%.1f percent" % fam_pct)
chk("no stale 2.5 factor in tex", "factor of $2.5$" not in tex,
"searched tex", needs_tex=True)
sc2 = rows("sec_sens_cmp.csv")
worst04 = min(min(float(r["ser_mask"]), float(r["ser_perm"]),
float(r["ser_pad"])) for r in sc2
if float(r["frac"]) <= 0.4)
chk("all three above 0.95 to 40 percent of key", worst04 > 0.95,
"min %.4f" % worst04)
rf = rows("refresh.csv")
res = max(1 - float(r["eve_invariant"]) for r in rf)
chk("refresh residual below 2.4e-3", res < 2.4e-3, "max %.2e" % res)
rk = rows("refresh_kpa.csv")
nb = max(0.9999847412 - float(r["ser_next_block"]) for r in rk)
chk("next block within 6e-4 of chance", nb < 6e-4, "max %.2e" % nb)
bc = rows("sec_brute_cmp.csv")
pm = min(float(r["ser_perm"]) for r in bc)
chk("permutation floor 0.9996", pm > 0.9996, "min %.5f" % pm)
md = {r["family"]: r for r in rows("maskdegen.csv")}
ks = [int(x) for x in md["learned"]["support99_per_key"].split("/")]
chk("learned keys degenerate: 5 to 8 of 64 entries",
min(ks) == 5 and max(ks) == 8 and int(md["learned"]["L"]) == 64,
md["learned"]["support99_per_key"])
chk("learned support overlap 0.10",
round(float(md["learned"]["mean_overlap"]), 2) == 0.10,
md["learned"]["mean_overlap"])
chk("degeneracy numbers in tex",
"$5$ to $8$ of the $64$ entries" in " ".join(tex.split())
and "only $0.10$ of the smaller of any two such sets" in " ".join(tex.split()),
"searched tex", needs_tex=True)
# --- why the permutation key is granted a shared permutation ---------
pv = {r["variant"]: float(r["legit_ser"]) for r in rows("perm_variant.csv")}
chk("shared permutation legitimate rate", abs(pv["shared"] - 0.053) < 1e-3,
"%.5f" % pv["shared"])
chk("per-user permutation legitimate rate",
abs(pv["per_user"] - 0.129) < 1e-3, "%.5f" % pv["per_user"])
if HAVE_TEX:
chk("quoted permutation cost in tex",
"at $0.129$ against $0.053$" in " ".join(tex.split()),
"searched tex", needs_tex=True)
# --- key-length sweep floor ------------------------------------------
# The eavesdropper column is an average over eight substitute-key draws,
# so the quoted floor must track the data and not one lucky draw.
kl = rows("sec_keylen.csv")
floor = min(float(r["eve_ser"]) for r in kl)
chk("eavesdropper floor over key length", 0.9983 < floor < 0.9984,
"%.6f" % floor)
if HAVE_TEX:
chk("quoted eavesdropper floor in tex", "$0.9983$" in tex,
"searched tex", needs_tex=True)
# --- quantities that used to be quoted with no artifact ---------------
import json as _json
rs = _json.load(open(base / "data" / "real_sec_stats.json"))
chk("token collision probability", abs(rs["token_collision"] - 0.0065) < 5e-5,
"%.6f" % rs["token_collision"])
vm = {r["check"]: r for r in rows("verify_math.csv")}
chk("V5 matched-over-blind ratio stored",
"V5 matched bias over blind RMS" in vm,
", ".join(sorted(vm))[:60])
chk("V8 cross-period remainder",
abs(float(vm["V8 cross-period remainder"]["empirical"])) < 5e-4,
vm["V8 cross-period remainder"]["empirical"])
# --- information-theoretic leakage, which no assertion covered ---------
it = {float(r["snr_db"]): r for r in rows("infotheory.csv")}[10.0]
chk("fixed-key leakage 1.34 bits",
abs(float(it["mi_eve_fixed_bits"]) - 1.34) < 5e-3, it["mi_eve_fixed_bits"])
chk("distinguishing advantage 0.27",
abs(float(it["tv_fixed"]) - 0.27) < 5e-3, it["tv_fixed"])
chk("refreshed leakage 0.055 bits",
abs(float(it["mi_eve_refresh_bits"]) - 0.055) < 5e-4,
it["mi_eve_refresh_bits"])
chk("secrecy rate 14.87 of 14.93",
abs(float(it["secrecy_rate_refresh_bits"]) - 14.87) < 5e-3
and abs(float(it["mi_legit_bits"]) - 14.93) < 5e-3,
"%s of %s" % (it["secrecy_rate_refresh_bits"], it["mi_legit_bits"]))
_fe = {(r["family"], r["keying"], float(r["snr_db"]), int(r["n_frames"])): r
for r in rows("family_enum.csv")}
_sf = _fe[("structured", "fixed", 10.0, 1)]
_s4 = _fe[("structured", "fixed", 10.0, 4)]
_sr = _fe[("structured", "refreshed", 10.0, 2)]
chk("structured family enumerable at 10 dB",
abs(float(_sf["outsider_recovery"]) - 0.905) < 5e-3
and abs(float(_s4["outsider_recovery"]) - 0.990) < 5e-3,
"N=1 %s, N=4 %s" % (_sf["outsider_recovery"], _s4["outsider_recovery"]))
chk("the refresh stops the outsider enumeration",
float(_sr["outsider_recovery"]) == 0.0,
"%s over 200 blocks" % _sr["outsider_recovery"])
chk("the refresh does not stop the insider closure",
abs(float(_sr["insider_recovery"]) - 0.980) < 5e-3,
"%s over 200 blocks" % _sr["insider_recovery"])
chk("the learned family defeats both attacks everywhere",
all(float(r["outsider_recovery"]) == 0.0
and float(r["insider_recovery"]) == 0.0
for r in rows("family_enum.csv") if r["family"] == "learned"),
"%d learned rows" % sum(1 for r in rows("family_enum.csv")
if r["family"] == "learned"))
_sl = rows("sec_snr_learned.csv")
_sn = {float(r["snr_db"]): float(r["legit"]) for r in rows("sec_snr.csv")}
chk("learned family tracks the structured one over the SNR range",
all(1.0 < float(r["legit"]) / _sn[float(r["snr_db"])] < 1.5
for r in _sl),
"ratio %.2f to %.2f" % (min(float(r["legit"]) / _sn[float(r["snr_db"])]
for r in _sl),
max(float(r["legit"]) / _sn[float(r["snr_db"])]
for r in _sl)))
_l10 = [float(r["legit"]) for r in _sl if float(r["snr_db"]) == 10.0][0]
chk("learned 0.061 at 10 dB", abs(_l10 - 0.061) < 5e-4, "%.5f" % _l10)
# The learned curves must be the regularized keys, not the unpenalized
# ones. Both are measured in sec_maskfam.csv and they differ by 0.003,
# which is larger than the spread of either, so matching the right row
# pins which family every figure draws. Cross-entropy alone drifts to a
# slot allocation whose key space is a support rather than a sphere, so
# drawing it would not support the key-space claim.
_fam = {r["family"]: float(r["legit_ser"]) for r in rows("sec_maskfam.csv")}
chk("the plotted learned family is the regularized one",
abs(_l10 - _fam["learned_reg"]) < abs(_l10 - _fam["learned"])
and abs(_l10 - _fam["learned_reg"]) < 1.5e-3,
"plotted %.5f, reg %.5f, plain %.5f"
% (_l10, _fam["learned_reg"], _fam["learned"]))
_bl = {int(r["K"]): float(r["ser_mask"])
for r in rows("sec_brute_learned.csv")}
chk("learned key resists a million random guesses",
abs(_bl[1_000_000] - 0.71) < 5e-3, "%.4f" % _bl[1_000_000])
_kl = {(float(r["snr_db"]), int(r["n_frames"])): float(r["eve_ser"])
for r in rows("kpa_learned.csv")}
chk("learned key falls to known plaintext like the structured one",
_kl[(10.0, 4)] < 0.08 and _kl[(10.0, 1)] > 0.9,
"N=1 %.3f, N=4 %.4f" % (_kl[(10.0, 1)], _kl[(10.0, 4)]))
_rs = {float(r["snr_db"]): float(r["ter_legit"])
for r in rows("real_sec_ter.csv")}
_rl = {float(r["snr_db"]): float(r["ter_legit"])
for r in rows("real_sec_ter_learned.csv")}
_rat = [_rl[k] / _rs[k] for k in _rs]
chk("learned keeps its uniform-source distance on real text",
all(1.10 < v < 1.25 for v in _rat),
"ratio %.2f to %.2f" % (min(_rat), max(_rat)))
# --- trends, which the value assertions above cannot see ---------------
_snr = rows("sec_snr.csv")
_lg = [float(r["legit"]) for r in _snr]
chk("legitimate SER falls monotonically with SNR",
all(a > b for a, b in zip(_lg, _lg[1:])), "%d points" % len(_lg))
chk("legitimate below the binary OMA reference at every SNR",
all(float(r["legit"]) < float(r["oma"]) for r in _snr),
"min margin %.3f" % min(1 - float(r["legit"]) / float(r["oma"])
for r in _snr))
_kl = rows("sec_keylen.csv")
chk("legitimate SER falls monotonically with key length",
all(float(a["legit_ser"]) > float(b["legit_ser"]) for a, b in zip(_kl, _kl[1:])),
"%d lengths" % len(_kl))
chk("legitimate surpasses the reference from L=16 onward",
all(float(r["legit_ser"]) < float(r["oma"]) for r in _kl
if r["oma"] != "nan" and int(float(r["L"])) >= 16),
"checked L>=16")
_ter = rows("real_sec_ter.csv")
chk("legitimate TER below OMA over the whole range",
all(float(r["ter_legit"]) < float(r["ter_oma"]) for r in _ter),
"%d points" % len(_ter))
chk("outsider TER stays above 0.9991",
min(float(r["ter_eve"]) for r in _ter) > 0.9991,
"min %.6f" % min(float(r["ter_eve"]) for r in _ter))
# --- files no assertion read ------------------------------------------
_us = rows("users.csv")
chk("keys stay exactly orthogonal at every load",
all(float(r["mask_xcorr"]) == 0.0 for r in _us),
"U up to %s" % _us[-1]["users"])
chk("eavesdropper never leaves chance across the load sweep",
all(float(r["eve_ser"]) > 0.999 for r in _us),
"min %.6f" % min(float(r["eve_ser"]) for r in _us))
_u = {r["users"]: r for r in _us}
chk("load endpoints 0.027 and 0.946",
abs(float(_u["2"]["legit_ser"]) - 0.027) < 5e-4
and abs(float(_u["32"]["legit_ser"]) - 0.946) < 5e-4,
"%.4f, %.4f" % (float(_u["2"]["legit_ser"]),
float(_u["32"]["legit_ser"])))
chk("the OMA crossing lies between U=16 and U=32",
float(_u["16"]["legit_ser"]) < float(_u["16"]["oma"])
and float(_u["32"]["legit_ser"]) > float(_u["32"]["oma"]),
"16: %.3f<%.3f, 32: %.3f>%.3f"
% (float(_u["16"]["legit_ser"]), float(_u["16"]["oma"]),
float(_u["32"]["legit_ser"]), float(_u["32"]["oma"])))
_csi = rows("csi.csv")
chk("phase residual moves the rate to 0.057 at 0.2 rad",
any(abs(float(r["legit_ser"]) - 0.057) < 1e-3 for r in _csi),
"%d rows" % len(_csi))
_sem = rows("semantic.csv")
chk("legitimate similarity at least 0.96 in both spaces",
all(float(r["legit"]) >= 0.96 for r in _sem if r["snr_db"] == "10.0"),
"%d rows" % len(_sem))
_cov = rows("cov_attack.csv")
chk("covariance attack reaches 0.26 at 300 same-key frames",
any(r["n_frames"] == "300" and abs(float(r["eve_ser"]) - 0.26) < 0.01
for r in _cov),
"%d rows" % len(_cov))
chk("unjammed reference is 0.053",
abs(col("sec_jam.csv", "nojam")[0] - 0.053) < 0.05, "sec_jam.csv read")
# --- the closed-form checks the manuscript quotes ----------------------
_vm = {r["check"]: r for r in rows("verify_math.csv")}
for _k, _c in [("V8 cross-period remainder", 0.0005),
("V9 score-variance ratio", 0.05),
("V10 format-matched OMA at 10 dB", 0.001),
("V3a bias slope in kappa", 0.03)]:
chk("stored check %s passes" % _k.split()[0],
_k in _vm and _vm[_k]["verdict"] == "PASS"
and float(_vm[_k]["abs_err"]) <= _c,
_vm[_k]["empirical"] if _k in _vm else "row missing")
chk("format-matched OMA quoted as 0.055",
"$0.055$ at $10$~dB" in tex and "the proposed $0.053$" in tex,
"Section VI-B",
needs_tex=True)
# --- tables against their generator -----------------------------------
# Every printed table cell must be the one make_tables.py derives from
# data/, so a rerun that moves a number cannot leave the manuscript behind.
if HAVE_TEX:
import io
import contextlib
import make_tables
buf = io.StringIO()
with contextlib.redirect_stdout(buf):
make_tables.compare_table()
# the key-family table was folded into the Section VI-F prose
pass
make_tables.refresh_tables()
rows = [r.strip() for r in buf.getvalue().split("\n")
if r.rstrip().endswith(r"\\")]
flat = " ".join(tex.split())
lost = [r for r in rows if " ".join(r.split()) not in flat]
chk("table rows match the generator", not lost,
"%d rows, %d missing" % (len(rows), len(lost)), needs_tex=True)
for r in lost:
print(" missing:", r[:78])
# --- abstract ---------------------------------------------------------
a = (tex.split(r"\begin{abstract}")[1].split(r"\end{abstract}")[0].strip()
if HAVE_TEX else "")
w = len(re.split(r"\s+", a)) if a else 0
chk("abstract <= 250 words", w <= 250, "%d words" % w, needs_tex=True)
chk("abstract has no abbreviations",
not re.findall(r"\b[A-Z]{2,}\b", a), str(re.findall(r"\b[A-Z]{2,}\b", a)),
needs_tex=True)
print()
print("ALL CONSISTENT" if ok else "INCONSISTENCIES FOUND")
# a checker that always exits zero cannot gate anything
import sys as _sys
_sys.exit(0 if ok else 1)