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Project-declaredLean 4.31.0 · mathlib@fabf563a7c95

Function binding interpolation branch maps to arsdh

KZG.CommitmentScheme.function_binding_interpolation_branch_maps_to_arsdh

Plain-language statement

The interpolation branch maps a function-binding violation to ARSDH.

Exact Lean statement

lemma function_binding_interpolation_branch_maps_to_arsdh {n L : ℕ}
    (hn : 1 ≤ n) (hpair : pairing g₁ g₂ ≠ 0)
    {τ : ZMod p} {srs : Vector G₁ (n + 1) × Vector G₂ 2} {cm : G₁}
    {queryOf responseOf : Fin L → ZMod p} {accepts : Fin L → Bool} {proofs : Fin L → G₁}
    (hsrs : srs = Groups.PowerSrs.generate (g₁ := g₁) (g₂ := g₂) n τ)
    (hgen : srs.1[0] ≠ 1)
    (hverify_all : ∀ i : Fin L, accepts i = true →
      KZG.verifyOpening (g₁ := g₁) (g₂ := g₂) (pairing := pairing)
        srs.2 cm (proofs i) (queryOf i) (responseOf i))
    (hFBcond : functionBindingCondExt n L (τ, srs, cm, queryOf, responseOf, accepts, proofs))
    {A S : Finset (Fin L)}
    (hqueryS : Set.InjOn queryOf ↑S)
    (hresS : findS n A cm srs queryOf responseOf = some S)
    (hfs_none : List.findSome?
        (fun i ↦ if srs.1[0] ^ (queryOf i).val = srs.1[1]'(Nat.lt_add_of_pos_left hn)
                  then some (queryOf i) else none)
        (List.finRange L) = none) :
    Groups.arsdhCondition n
      (τ, (interpolationArsdhOutput (p := p) (G₂ := G₂) S
        ({ srs := srs, cm := cm, queryOf := queryOf, responseOf := responseOf,
           accepts := accepts, proofs := proofs } :
          FunctionBindingExtTranscript (p := p) n L G₁ G₂)).toTuple)

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma function_binding_interpolation_branch_maps_to_arsdh {n L : }    (hn : 1  n) (hpair : pairing g₁ g₂  0)    {τ : ZMod p} {srs : Vector G₁ (n + 1) × Vector G₂ 2} {cm : G₁}    {queryOf responseOf : Fin L  ZMod p} {accepts : Fin L  Bool} {proofs : Fin L  G₁}    (hsrs : srs = Groups.PowerSrs.generate (g₁ := g₁) (g₂ := g₂) n τ)    (hgen : srs.1[0]  1)    (hverify_all :  i : Fin L, accepts i = true       KZG.verifyOpening (g₁ := g₁) (g₂ := g₂) (pairing := pairing)        srs.2 cm (proofs i) (queryOf i) (responseOf i))    (hFBcond : functionBindingCondExt n L (τ, srs, cm, queryOf, responseOf, accepts, proofs))    {A S : Finset (Fin L)}    (hqueryS : Set.InjOn queryOf ↑S)    (hresS : findS n A cm srs queryOf responseOf = some S)    (hfs_none : List.findSome?        (fun i  if srs.1[0] ^ (queryOf i).val = srs.1[1]'(Nat.lt_add_of_pos_left hn)                  then some (queryOf i) else none)        (List.finRange L) = none) :    Groups.arsdhCondition n      (τ, (interpolationArsdhOutput (p := p) (G₂ := G₂) S        ({ srs := srs, cm := cm, queryOf := queryOf, responseOf := responseOf,           accepts := accepts, proofs := proofs } :          FunctionBindingExtTranscript (p := p) n L G₁ G₂)).toTuple) := by  simp only [interpolationArsdhOutput, FunctionBindingArsdhOutput.toTuple,    Groups.arsdhCondition, ne_eq, one_div]  have hresS_symm : some S = findS n A cm srs queryOf responseOf := hresS.symm  refine ?_, ?_, ?_, ?_  · rw [Finset.card_image_of_injOn hqueryS]    exact find_s_card n cm A S srs queryOf responseOf hresS_symm  · have hτneq_all :  i : Fin L, queryOf i  τ :=      query_ne_tau_of_find_query_with_srs_power_none        (g₁ := g₁) hn τ srs queryOf hsrs hfs_none    have hτ_not_image : τ  S.image queryOf := by      simp only [Finset.mem_image, not_exists, not_and]      intro i _      exact hτneq_all i    exact prod_x_sub_c_eval_ne_zero hτ_not_image  · intro hdiv    have hcm_eq_c' : cm =        commit srs.1 ((CLagrange.interpolate S queryOf responseOf).val.coeffFin.val) :=      div_eq_one.mp hdiv    exact (find_s_diverges n cm A S queryOf responseOf srs hresS_symm) hcm_eq_c'.symm  · have hcard : S.card = n + 1 :=      find_s_card n cm A S srs queryOf responseOf hresS_symm    have hdeg : (CLagrange.interpolate S queryOf responseOf).degree  (n : WithBot ) := by      exact interp_degree_le_of_card S queryOf responseOf hqueryS hcard    have hS_ne : S.Nonempty := by      rw [ Finset.card_pos, hcard]; exact Nat.succ_pos _    have hτneq :  i  S, queryOf i  τ := by      intro i _      exact query_ne_tau_of_find_query_with_srs_power_none        (g₁ := g₁) hn τ srs queryOf hsrs hfs_none i    have hVer :  i  S,        KZG.verifyOpening (g₁ := g₁) (g₂ := g₂) (pairing := pairing)          srs.2 cm (proofs i) (queryOf i) (responseOf i) := by      intro i _      exact hverify_all i (hFBcond.1 i (Finset.mem_univ _))    have key := h1_zs_eq_h2_prime (g₁ := g₁) (g₂ := g₂) (pairing := pairing)      n τ cm S queryOf responseOf proofs srs hn hsrs hτneq hVer      hgen hpair hdeg hS_ne hqueryS    simpa only [one_div] using key
Project
ArkLib
License
Apache-2.0
Commit
fad5cbf80877
Source
ArkLib/Commitments/Functional/KZG/FunctionBinding/DegreeConflict.lean:826-885

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