Run Trace target eq of mem context Fork
FiatShamir.Fork.runTrace_target_eq_of_mem_contextFork
Plain-language statement
If two successful contextual forks select the same fork index, their forgery targets agree.
Exact Lean statement
lemma runTrace_target_eq_of_mem_contextFork
[DecidableEq M] [DecidableEq Commit] [DecidableEq Chal] [SampleableType Chal] [Inhabited Chal]
(nmaAdv : SignatureAlg.managedRoNmaAdv
(FiatShamir (m := OracleComp (unifSpec + (M × Commit →ₒ Chal))) σ hr M))
(qH : ℕ) (pk : Stmt)
(x₁ x₂ : Trace (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal))
(s : Fin (qH + 1))
(hsup : some (x₁, x₂) ∈ support (contextFork (runTrace σ hr M nmaAdv pk)
(fun j : ℕ ⊕ Unit => match j with | .inl _ => 0 | .inr () => qH) (Sum.inr ())
(forkPoint (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal) qH)))
(h₁ : forkPoint (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal)
qH x₁ = some s)
(h₂ : forkPoint (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal)
qH x₂ = some s) :
x₁.target = x₂.targetFormal artifact
Lean source
lemma runTrace_target_eq_of_mem_contextFork [DecidableEq M] [DecidableEq Commit] [DecidableEq Chal] [SampleableType Chal] [Inhabited Chal] (nmaAdv : SignatureAlg.managedRoNmaAdv (FiatShamir (m := OracleComp (unifSpec + (M × Commit →ₒ Chal))) σ hr M)) (qH : ℕ) (pk : Stmt) (x₁ x₂ : Trace (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal)) (s : Fin (qH + 1)) (hsup : some (x₁, x₂) ∈ support (contextFork (runTrace σ hr M nmaAdv pk) (fun j : ℕ ⊕ Unit => match j with | .inl _ => 0 | .inr () => qH) (Sum.inr ()) (forkPoint (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal) qH))) (h₁ : forkPoint (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal) qH x₁ = some s) (h₂ : forkPoint (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal) qH x₂ = some s) : x₁.target = x₂.target := by letI : Fintype Chal := Fintype.ofFinite Chal letI : IsUniformSpec ((Unit →ₒ Chal) : OracleSpec _) := IsUniformSpec.ofFintypeInhabited _ let qb : ℕ ⊕ Unit → ℕ := fun j => match j with | .inl _ => 0 | .inr () => qH let cf := forkPoint (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal) qH let main := runTrace σ hr M nmaAdv pk obtain ⟨path, s', located, second, hpath, hcf₁, _hsecond, _hne, _hcf₂, hx₁, hx₂⟩ := contextFork_success main qb (Sum.inr ()) cf hsup have hs' : s' = s := by apply Option.some.inj calc some s' = cf (PFunctor.FreeM.output main path) := hcf₁.symm _ = cf x₁ := by rw [hx₁] _ = some s := h₁ subst s' let commonLog : QueryLog (wrappedSpec Chal) := located.occurrence.before have hfirst := replayPathResult_mem_support_replayFirstRun main path hpath have hsecond := replayPathResult_mem_support_replayFirstRun main second.path (mem_support_replayFirstPath main second.path) have hxlog₁ : (x₁, (replayPathResult main path).2) ∈ support (replayFirstRun main) := by simpa [replayPathResult, pathLogResult, hx₁] using hfirst have hxlog₂ : (x₂, (replayPathResult main second.path).2) ∈ support (replayFirstRun main) := by simpa [replayPathResult, pathLogResult, hx₂] using hsecond have hlog₁ : (replayPathResult main path).2 = commonLog ++ (⟨Sum.inr (), located.completion.answer⟩ :: (replayPathResult (located.occurrence.resume located.completion.answer) located.completion.suffix).2) := by have htrace := congrArg (fun p : PFunctor.FreeM.Path main => (show QueryLog (wrappedSpec Chal) from PFunctor.FreeM.Path.trace main p)) located.path_eq calc (replayPathResult main path).2 = (replayPathResult main located.completion.path).2 := htrace.symm _ = _ := by change PFunctor.FreeM.Path.trace main located.completion.path = List.append (show PFunctor.TraceList (wrappedSpec Chal).toPFunctor from commonLog) (⟨Sum.inr (), located.completion.answer⟩ :: PFunctor.FreeM.Path.trace (located.occurrence.resume located.completion.answer) located.completion.suffix) unfold commonLog exact PFunctor.FreeM.Cursor.Occurrence.trace_plug located.occurrence located.completion.answer located.completion.suffix have hlog₂ : (replayPathResult main second.path).2 = commonLog ++ (⟨Sum.inr (), second.answer⟩ :: (replayPathResult (located.occurrence.resume second.answer) second.suffix).2) := by change PFunctor.FreeM.Path.trace main second.path = List.append (show PFunctor.TraceList (wrappedSpec Chal).toPFunctor from commonLog) (⟨Sum.inr (), second.answer⟩ :: PFunctor.FreeM.Path.trace (located.occurrence.resume second.answer) second.suffix) unfold commonLog exact PFunctor.FreeM.Cursor.Occurrence.trace_plug located.occurrence second.answer second.suffix have htakeEq := runTrace_queryLog_take_eq σ hr M (Resp := Resp) nmaAdv pk (x₁ := x₁) (x₂ := x₂) (outerLog₁ := (replayPathResult main path).2) (outerLog₂ := (replayPathResult main second.path).2) hxlog₁ hxlog₂ (p := commonLog) (v₁ := located.completion.answer) (v₂ := second.answer) (rest₁ := (replayPathResult (located.occurrence.resume located.completion.answer) located.completion.suffix).2) (rest₂ := (replayPathResult (located.occurrence.resume second.answer) second.suffix).2) hlog₁ hlog₂ have hprefixCount : commonLog.countQ (fun x => x = Sum.inr ()) = (↑s : ℕ) := by calc commonLog.countQ (fun x => x = Sum.inr ()) = PFunctor.TraceList.occurrences (P := (wrappedSpec Chal).toPFunctor) (Sum.inr ()) (show PFunctor.TraceList (wrappedSpec Chal).toPFunctor from commonLog) := QueryLog.countQ_eq_occurrences commonLog (Sum.inr ()) _ = (↑s : ℕ) := by simp [commonLog] rw [hprefixCount] at htakeEq have htgt₁ : x₁.queryLog[(↑s : ℕ)]? = some x₁.target := forkPoint_getElem?_eq_some_target (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal) h₁ have htgt₂ : x₂.queryLog[(↑s : ℕ)]? = some x₂.target := forkPoint_getElem?_eq_some_target (M := M) (Commit := Commit) (Resp := Resp) (Chal := Chal) h₂ have hgetElemTake (l : List (M × Commit)) : (l.take ((↑s : ℕ) + 1))[(↑s : ℕ)]? = l[(↑s : ℕ)]? := List.getElem?_take_of_lt (Nat.lt_succ_self _) apply Option.some.inj rw [← htgt₁, ← htgt₂, ← hgetElemTake x₁.queryLog, ← hgetElemTake x₂.queryLog, htakeEq]- Project
- VCVio
- License
- Apache-2.0
- Commit
- 2ceb2d825ee3
- Source
- VCVio/CryptoFoundations/FiatShamir/Sigma/Fork.lean:1231-1345
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