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Project-declaredLean 4.31.0 · mathlib@fabf563a7c95

T sdh denominator ne zero of opening equations

KZG.CommitmentScheme.t_sdh_denominator_ne_zero_of_opening_equations

Plain-language statement

If two accepted openings at the same query give different responses, the t-SDH denominator τ + (-query) cannot vanish. This is the small algebraic contradiction used to avoid a separate query = τ branch in the binding reduction.

Exact Lean statement

lemma t_sdh_denominator_ne_zero_of_opening_equations
    (τ query resp₁ resp₂ cm prf₁ prf₂ : ZMod p) (hresp : resp₁ ≠ resp₂)
    (hverifyEq₁ : cm - resp₁ = prf₁ * (τ - query))
    (hverifyEq₂ : cm - resp₂ = prf₂ * (τ - query)) :
    τ + -query ≠ 0

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma t_sdh_denominator_ne_zero_of_opening_equations    (τ query resp₁ resp₂ cm prf₁ prf₂ : ZMod p) (hresp : resp₁  resp₂)    (hverifyEq₁ : cm - resp₁ = prf₁ *- query))    (hverifyEq₂ : cm - resp₂ = prf₂ *- query)) :    τ + -query  0 := by  intro hzero  have hτq : τ - query = 0 := by    simpa [sub_eq_add_neg] using hzero  have hcm₁ : cm = resp₁ := by    simp only [hτq, MulZeroClass.mul_zero] at hverifyEq₁    exact sub_eq_zero.mp hverifyEq₁  have hcm₂ : cm = resp₂ := by    simp only [hτq, MulZeroClass.mul_zero] at hverifyEq₂    exact sub_eq_zero.mp hverifyEq₂  exact hresp (hcm₁.symm.trans hcm₂)
Project
ArkLib
License
Apache-2.0
Commit
fad5cbf80877
Source
ArkLib/Commitments/Functional/KZG/Binding.lean:138-152

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Plain-language statement

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