3 Commits

Author SHA1 Message Date
Marcin Pawlowski
e4d3d3a0f7
blend: close the attribution bracket with a neighbourhood-observability model
The a/d estimator credits the adversary only with the sender own links, which
understates it: to rule out that X was forwarding it need not hold X incoming
link, only have seen the message anywhere upstream. That gives

    confidence = 1 / (1 + (1-f_adv)^L)

for L upstream hops, with the local model as the L=1 case.

L is not free -- the graph fixes it. A forwarder sits about halfway along a route
and the peer graph is low-diameter: mean hop distance 5.15 at degree 8, so L ~ 2.6.
Confidence rises from 0.56 to 0.64 at f_adv = 0.2, but 0.9 would need ~10 upstream
hops. The low diameter that makes propagation fast is exactly what starves the
adversary of observation points.

So the bracket closes near the local model rather than near certainty, and the
binary full_deanon treatment is NOT rescued by neighbourhood effects. Both ends
are reported rather than one being chosen, since confident attribution is a
threshold question: an adversary content with 0.64 attributes most senders, one
demanding 0.9 attributes almost none.

What remains unmodelled is an adversary combining this structural evidence with
the timing evidence of 3.11.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-06 18:00:01 +02:00
Marcin Pawlowski
3c7fef64d0
blend: attribution confidence -- one adversarial peer is not an identification
full_deanon counted any sender with an adversarial peer as identified. Capturing a
cascade tells the adversary WHICH message it is following, not WHO started it:
seeing an honest X transmit is equally consistent with X having received it from a
peer the adversary cannot watch. Separating the two gives

    confidence = 1/(2 - a/d) = d/(2d - a)

for a adversarial peers of degree d. The path length does not enter -- the
conditioning event already fixes the relays as adversarial, so an honest X is not
one of them for this message.

The consequence is large. One peer of eight is worth 0.53, barely above the 0.5
prior, and 90% confidence needs a >= 8: every peer, which is the ECLIPSE condition
rather than the observation condition. Measured, attributable_frac_90 equals
eclipsed_frac exactly. At f_adv = 0.2, degree 8 that is 2.6e-6 against an
observed_frac of 0.83 -- the published figure overstates confident origination by
five orders of magnitude.

Stated in the report as a bracket rather than a replacement: full_deanon is the
upper bound on adversary capability, this is the lower bound, and the truth lies
between because the adversary also learns from the sender neighbourhood. Closing
that gap needs a k-hop observability model and is recorded as open in section 5.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-06 17:59:59 +02:00
Marcin Pawlowski
f51630e509
Rename the simulator and report from pd to blend
The study started as a peering-degree question and grew well past it: propagation,
adversary exposure, deanonymization and time-to-link, reliability under uniform
and correlated churn, messaging redundancy, and cover traffic. The pd name no
longer describes it.

tools/simulators/blend/pd/ -> tools/simulators/blend/, package src/pd -> src/blend,
and reports/blend/pd/ -> reports/blend/. Moved with git mv so history follows.

The text substitutions are deliberately narrow. pd is also the conventional pandas
alias, and pandas genuinely has a pd.plotting submodule, so a blanket pd. -> blend.
rewrite would have corrupted four files. Only package-unambiguous forms were
changed: from pd.X, -m pd.X, pd.<our module>, PD_BYTES_BUDGET, src/pd, and the
pyproject name. All four import pandas as pd lines are untouched and verified.

Both READMEs reframed: peering degree is now presented as the primary axis that
ties the others together rather than as the subject, and the relative links, which
lost a directory level in the move, are corrected.

Verified after the move: ruff clean, 101 tests, 45 verify anchors, make targets,
the script shims, an end-to-end smoke run, and data/report_numbers.py still
reproducing the report tables from the checked-in evidence.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-06 17:59:59 +02:00