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
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2026-07-30 15:04:09 +02:00