feat(xmss): deterministic fake prover for Shadow sims (ZEAM_SHADOW_XMSS_FAKE)#1007
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feat(xmss): deterministic fake prover for Shadow sims (ZEAM_SHADOW_XMSS_FAKE)#1007GrapeBaBa wants to merge 1 commit into
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…SS_FAKE) Opt-in stub that replaces the real leanMultisig STARK prove/verify FFI with a deterministic SHA-256 counter-mode proof when ZEAM_SHADOW_XMSS_FAKE is set. Under Shadow the real prover runs as native compute charged to virtual time, an uncontrollable baseline on top of the injected --shadow-xmss-*-rate sleep; the stub removes that baseline so the injected rate is the sole prover-cost knob for cost-sweep experiments. - shadow_cost: one process-global fake toggle, env-only, off by default. - aggregation: aggregateType1 / mergeType1ToType2 / splitType2ByMessage / verifyType1 / verifyType2 emit the stub; the sim-cost sleeps still run on the virtual clock, only the real prove/verify is bypassed. - Stub bytes are seeded only from wire-bound inputs (message hash, slot, child-proof bytes, participant counts), never per-process pointer handles, so every node yields identical bytes for identical inputs (consensus-safe). Off by default: with no rate set and fake off, behavior is byte-identical to before. Verified on Zig 0.16.0: test-shadow-cost + zig build test (-Dprover=dummy) green, including 4 new fake-path tests.
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Summary
Adds an opt-in deterministic fake XMSS prover for Shadow simulation, gated behind the
ZEAM_SHADOW_XMSS_FAKEenv var (off by default). When enabled, the five leanMultisig STARK FFI wrappers —aggregateType1,mergeType1ToType2,splitType2ByMessage,verifyType1,verifyType2— return a deterministic SHA-256 counter-mode stub instead of calling the real prover/verifier.Why
Under Shadow, the real STARK prove/verify runs as native compute and is charged to virtual time as an uncontrollable baseline on top of the injected
--shadow-xmss-*-ratesleep. That contaminates prover-cost-sweep experiments — you can't isolate the effect of the injected rate. Replacing the prover with a deterministic stub removes the baseline, leaving the injected rate as the sole, clean prover-cost knob.The existing
--shadow-xmss-*-ratesim-cost sleeps are preserved and still run on the virtual clock; only the real STARK compute is bypassed.Safety / determinism
Scope
zeam-side only. The Shadow operator tooling that delivers the env var to nodes (the
lean-shadow-fuzzergenerate-shadow-yaml.shpatch) lives in a separate repo and is a follow-up.Test plan
zig build test-shadow-cost(Zig 0.16.0) — fake toggle + delay modelzig build test -Dprover=dummy(Zig 0.16.0) — xmss tests including 4 new fake-path tests:verifyType2round-tripverifyType1round-trip