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Project-declaredLean 4.31.0 · mathlib@fabf563a7c95

Binding Advantage le module SIS of short Closure

ArkLib.Lattices.Ajtai.Simple.bindingAdvantage_le_moduleSIS_of_shortClosure

Plain-language statement

Binding reduces to Module-SIS for any commitment/Module-SIS shortness predicates closed under differences.

Exact Lean statement

theorem bindingAdvantage_le_moduleSIS_of_shortClosure {rows cols : Nat}
    [SampleableType (PublicParams Φ rows cols)]
    [DecidableEq (Message Φ cols)] [DecidableEq (Commitment Φ rows)]
    (isShort : Message Φ cols → Bool) (isShortSIS : ModuleSIS.Solution Φ cols → Bool)
    (hsub : ∀ s₁ s₂ : Message Φ cols, isShort s₁ = true → isShort s₂ = true →
      isShortSIS (s₁ - s₂) = true)
    (adv : BindingAdv (PublicParams Φ rows cols) (Message Φ cols) (Commitment Φ rows) Opening) :
    bindingAdvantage (commitmentScheme Φ rows cols isShort) adv ≤
      ModuleSIS.advantage Φ rows cols isShortSIS (bindingAdvToModuleSIS Φ isShortSIS adv)

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
theorem bindingAdvantage_le_moduleSIS_of_shortClosure {rows cols : Nat}    [SampleableType (PublicParams Φ rows cols)]    [DecidableEq (Message Φ cols)] [DecidableEq (Commitment Φ rows)]    (isShort : Message Φ cols  Bool) (isShortSIS : ModuleSIS.Solution Φ cols  Bool)    (hsub :  s₁ s₂ : Message Φ cols, isShort s₁ = true  isShort s₂ = true       isShortSIS (s₁ - s₂) = true)    (adv : BindingAdv (PublicParams Φ rows cols) (Message Φ cols) (Commitment Φ rows) Opening) :    bindingAdvantage (commitmentScheme Φ rows cols isShort) adv       ModuleSIS.advantage Φ rows cols isShortSIS (bindingAdvToModuleSIS Φ isShortSIS adv) := by  unfold bindingAdvantage CommitmentScheme.bindingExp ModuleSIS.advantage    SIS.advantage SIS.experiment ModuleSIS.problem bindingAdvToModuleSIS    commitmentScheme ModuleSIS.relation  simp only [bind_pure_comp, Functor.map_map]  refine probOutput_bind_mono fun A _ => ?_  refine probOutput_bind_mono fun c, s₁, o₁, s₂, o₂ _ => ?_  refine probOutput_pure_bool_le _ _ (fun hwin => ?_)  simp only [Bool.and_eq_true, decide_eq_true_eq] at hwin   obtain ⟨⟨hne, hshort₁, hverify₁, hshort₂, hverify₂ := hwin  have hc₁ : commit Φ A s₁ = c := (verify_eq_true_iff Φ A s₁ c o₁).1 hverify₁  have hc₂ : commit Φ A s₂ = c := (verify_eq_true_iff Φ A s₂ c o₂).1 hverify₂  have hmat : A *ᵥ s₁ = A *ᵥ s₂ := by simpa [commit] using hc₁.trans hc₂.symm  refine ⟨⟨sub_ne_zero.mpr hne, hsub s₁ s₂ hshort₁ hshort₂, ?_  rw [matVecMul_sub, hmat, sub_self]
Project
ArkLib
License
Apache-2.0
Commit
fad5cbf80877
Source
ArkLib/Commitments/Ordinary/Ajtai/Simple/Security.lean:49-71

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