Query Log length le of nma Hash Query Bound
FiatShamir.Fork.queryLog_length_le_of_nmaHashQueryBound
Plain-language statement
Running the inner unifForward + roImpl simulator against a source computation with an nmaHashQueryBound Q can grow the internal queryLog by at most Q. Each source Sum.inr step consumes one unit of the nmaHashQueryBound budget, while roImpl appends to queryLog only on a cache miss, hence at most once per such step.
Exact Lean statement
theorem queryLog_length_le_of_nmaHashQueryBound
[DecidableEq M] [DecidableEq Commit] [SampleableType Chal] {α : Type}
{oa : OracleComp (unifSpec + (M × Commit →ₒ Chal)) α} {Q : ℕ}
(hQ : nmaHashQueryBound (M := M) (Commit := Commit) (Chal := Chal) (oa := oa) Q)
(st : SimState M Commit Chal) {z : α × SimState M Commit Chal}
(hz : z ∈ support ((simulateQ (unifForward M Commit Chal + roImpl M Commit Chal) oa).run st)) :
z.2.2.length ≤ st.2.length + QFormal artifact
Lean source
theorem queryLog_length_le_of_nmaHashQueryBound [DecidableEq M] [DecidableEq Commit] [SampleableType Chal] {α : Type} {oa : OracleComp (unifSpec + (M × Commit →ₒ Chal)) α} {Q : ℕ} (hQ : nmaHashQueryBound (M := M) (Commit := Commit) (Chal := Chal) (oa := oa) Q) (st : SimState M Commit Chal) {z : α × SimState M Commit Chal} (hz : z ∈ support ((simulateQ (unifForward M Commit Chal + roImpl M Commit Chal) oa).run st)) : z.2.2.length ≤ st.2.length + Q := by induction oa using OracleComp.inductionOn generalizing Q st z with | pure x => obtain rfl : z = (x, st) := by simpa [simulateQ_pure, StateT.run_pure, support_pure] using hz simp | query_bind t mx ih => rw [nmaHashQueryBound_query_bind_iff (M := M) (Commit := Commit) (Chal := Chal)] at hQ rw [simulateQ_query_bind, StateT.run_bind, support_bind] at hz simp only [Set.mem_iUnion] at hz obtain ⟨us, hus, hz'⟩ := hz cases t with | inl n => rcases st with ⟨cache, log⟩ obtain ⟨u, rfl⟩ : us ∈ Set.range (fun u => (u, cache, log)) := by simpa [QueryImpl.add_apply_inl, unifForward, support_map] using hus simpa using ih u (hQ.2 u) (cache, log) hz' | inr mc => rcases st with ⟨cache, log⟩ cases hcache : cache mc with | some v => have hus' : us ∈ ({(v, cache, log)} : Set _) := by convert hus using 1 <;> simp [QueryImpl.add_apply_inr, roImpl, StateT.run_bind, StateT.run_get, hcache, support_pure] obtain rfl := Set.mem_singleton_iff.mp hus' have hrec : z.2.2.length ≤ log.length + (Q - 1) := by simpa using ih v (hQ.2 v) (cache, log) hz' exact le_trans hrec (Nat.add_le_add_left (Nat.sub_le _ _) _) | none => obtain ⟨u, rfl⟩ : us ∈ Set.range (fun u : Chal => (u, cache.cacheQuery mc u, log ++ [mc])) := by convert hus using 1 <;> simp [QueryImpl.add_apply_inr, roImpl, StateT.run_bind, StateT.run_get, hcache, StateT.run_set, support_map] have hrec : z.2.2.length ≤ (log ++ [mc]).length + (Q - 1) := by simpa using ih u (hQ.2 u) ((cache.cacheQuery mc u : (M × Commit →ₒ Chal).QueryCache), log ++ [mc]) hz' have hQpos : 0 < Q := hQ.1 simp only [List.length_append, List.length_singleton] at hrec ⊢ lia- Project
- VCVio
- License
- Apache-2.0
- Commit
- 2ceb2d825ee3
- Source
- VCVio/CryptoFoundations/FiatShamir/Sigma/Fork.lean:161-208
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