Marcin Pawlowski 6ad63ce2f3
Add pd: peering-degree Blend Monte-Carlo graph simulator
Static-graph simulator quantifying how a node's peering degree trades off
propagation speed, adversary exposure, deanonymization, and reliability in the
Blend network. Scales to 1e6 nodes (sparse CSR + sampled Dijkstra); the
adversary and deanonymization metrics are exact at every N.

Model (ms): seeded d-regular peer graph (matching-union), Blend cascade
(sender -> blend_hops timed-release mix relays -> final flood), geographic link
base + exponential transport jitter, per-node processing lag, free-running
release-clock mixing.

Metrics:
- propagation: full-delay mean/p50/p90/p99, path/broadcast split, coverage times
- reliability: message success-delivery-rate ~ (1-unresponsive_frac)^blend_hops
  and flood coverage, with unresponsive nodes modelled as routing holes
- adversary (exact): observed/eclipsed fractions, random + worst-case placement
- deanonymization (exact): P(whole blend path adversarial) ~ f_adv^blend_hops,
  and full deanonymization (path adversarial AND honest sender peered with an
  adversary) = deanon_rate * observed_frac

Deterministic blake2b seed streams, three parquet tables, joblib parallelism,
memguard, an analytic verify harness, 50 unit tests, and an auto-installing
Makefile.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-08-06 17:59:55 +02:00

40 lines
1.6 KiB
Python

from pd.config import SimConfig
from pd.rng import (
graph_seedseq,
responsive_seedseq,
rng_for,
round_seedseq,
seedseq_for,
)
def test_deterministic():
c = SimConfig(n_nodes=1000, degree=8, graph_seed=3)
assert seedseq_for(c).entropy == seedseq_for(c).entropy
a = rng_for(c).integers(0, 10**9, size=5)
b = rng_for(c).integers(0, 10**9, size=5)
assert list(a) == list(b)
def test_graph_seed_is_topology_only():
base = SimConfig(n_nodes=1000, degree=8, graph_seed=3, f_adv=0.0, blend_hops=2)
same_topo = SimConfig(n_nodes=1000, degree=8, graph_seed=3, f_adv=0.4, blend_hops=5,
adversary_mode="worstcase_coverage", n_rounds=999)
assert graph_seedseq(base).entropy == graph_seedseq(same_topo).entropy
diff_topo = SimConfig(n_nodes=1000, degree=8, graph_seed=4)
assert graph_seedseq(base).entropy != graph_seedseq(diff_topo).entropy
def test_responsive_seed_depends_on_frac_only():
c = SimConfig(n_nodes=1000, degree=8, graph_seed=3)
# fixed per (topology, unresponsive_frac); different frac -> different responsive draw
assert responsive_seedseq(c, 0.1).entropy == responsive_seedseq(c, 0.1).entropy
assert responsive_seedseq(c, 0.1).entropy != responsive_seedseq(c, 0.2).entropy
def test_round_seed_includes_unresponsive_frac():
c = SimConfig(n_nodes=1000, degree=8, graph_seed=3)
a = round_seedseq(c, blend_hops=3, max_blend_delay=3, unresponsive_frac=0.0)
b = round_seedseq(c, blend_hops=3, max_blend_delay=3, unresponsive_frac=0.2)
assert a.entropy != b.entropy