Marcin Pawlowski e9b79ce90a
blend: attribution evidence at the reported scale, and a figure for the timing study
Two gaps left by the previous review.

Section 3.4 quoted the attribution bracket at N=20,000 while the only committed
evidence carrying those columns was the timing run at N=2,000, so a reader diffing
report against data saw different numbers for the same quantity. Added
configs/attribution.yaml and a make target: it records both bounds and the graph
hop distance at the reported scale, cheaply, since the adversary and
deanonymization metrics are closed-form and the hop distance is a property of the
topology. It reproduces the section exactly -- L = 2.58 and neighbourhood
confidence 0.640 at degree 8, f_adv 0.2.

It also surfaces a result the smaller run could not: degree cuts both ways. A
sparser graph has longer routes, so it offers the adversary more upstream places
to see the message -- L is 4.18 at degree 4 against 1.93 at degree 16, lifting
neighbourhood confidence from 0.61 to 0.72. The low diameter that makes
propagation fast also starves the adversary, one of the few places where raising
the degree helps anonymity rather than hurting it.

Section 3.11 was the only section without a figure. Fig 25 plots MAP success
against the effective anonymity set for both release designs: the dashed sets
separate far faster than the solid best-guess curves, which is the whole argument
for not trusting perplexity alone.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-06 18:00:02 +02:00
..

Evidence of record

The sweep outputs behind every number in the report. The simulator does not commit its own runs/ directory — these are the copies of record, kept so that any figure or table can be re-derived, or challenged, without re-running hours of compute.

Each run directory holds the three tables the simulator writes: propagation.parquet, adversary.parquet and deanon.parquet.

directory config sampling backs
default/ configs/default.yaml 1 000 rounds × 8 seeds = 8 000/cell §3.1§3.5 — delay, observation, eclipse, deanonymization, delivery, coverage
redundancy/ configs/redundancy.yaml 1 200 × 8 = 9 600/cell §3.8 — messaging redundancy R = 1…4
percolation/ configs/percolation.yaml 800 × 8 = 6 400/cell §3.5 — the churn threshold u_c = 1 1/(degree 1)
correlated-churn/ configs/correlated-churn.yaml 800 × 8 = 6 400/cell §3.9 — correlated AS/region outages vs uniform churn
fullscale/ configs/fullscale.yaml 64 × 3 = 192/cell §5 — the 10⁶ scaling check (deliberately lighter; not a source of headline numbers)
cover-traffic/ configs/cover-traffic.yaml 900 s timeline × 4 seeds §3.10 — blending, mixing, and the emission-quota stake ceiling. Carries a fourth table, traffic.parquet
attribution/ configs/attribution.yaml closed-form + 4 seeds §3.4 — the attribution bracket at the report's scale: local confidence, attributable fractions, upstream hops, neighbourhood confidence
timing/ configs/timing.yaml 120 s timeline × 3 seeds §3.11 — the two release designs under a timing attack, and the minimum-interval control

The linkability results (§3.6§3.7) and both deanonymization rates are closed forms over these tables rather than separate measurements, so they have no run of their own — blend.linkability derives them and make verify checks them against Monte-Carlo.

Regenerating the report's numbers

python report_numbers.py

prints every quoted value straight from the parquets here -- the §3.1§3.5 and §3.8 tables with their across-topology standard errors, and the §3.9§3.11 tables and the §3.4 attribution bracket from their own runs. That is the fastest way to check a table in the report against its evidence. It takes optional paths (report_numbers.py <default> <redundancy> <percolation>) if you want to point it at fresh runs instead.

Regenerating the data itself

From tools/simulators/blend: make sweep, make redundancy, make percolation, make correlated-churn, make sweep-fullscale. Results land in that simulator's runs/<timestamp>_<label>/. Note that the seed streams depend on the configuration, so re-running reproduces the statistics, not bit-identical numbers, unless the config is unchanged — in which case it does reproduce exactly.

Two runs from the same session are deliberately not kept: the smoke runs (throwaway, far too noisy to interpret) and an earlier 144-rounds/cell redundancy grid that was superseded because its sampling error produced a non-monotonic delivery curve — the reason redundancy/ samples 9 600.