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Project-declaredLean 4.32.0 · mathlib@81a5d257

Perfectly Correct

FiatShamir.perfectlyCorrect

Plain-language statement

Completeness of the Fiat-Shamir signature scheme follows from completeness of the underlying Σ-protocol.

Exact Lean statement

theorem perfectlyCorrect [SampleableType Chal]
    (hc : σ.PerfectlyComplete) :
    SignatureAlg.PerfectlyComplete
      (FiatShamir (m := OracleComp (unifSpec + (M × Commit →ₒ Chal))) σ hr M)
      (runtime M)

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
theorem perfectlyCorrect [SampleableType Chal]    (hc : σ.PerfectlyComplete) :    SignatureAlg.PerfectlyComplete      (FiatShamir (m := OracleComp (unifSpec + (M × Commit Chal))) σ hr M)      (runtime M) := by  intro msg  rw [perfectlyCorrect_evalDist_eq σ hr M msg]  change    Pr[= true | (do      let (pk, sk)  hr.gen      let (c, e)  σ.commit pk sk      let r  $ᵗ Chal      let s  σ.respond pk sk e r      pure (σ.verify pk c r s) : ProbComp Bool)] = 1  vcstep  vcstep using (fun x => OracleComp.ProgramLogic.propInd (x  support hr.gen))  · simpa [OracleComp.ProgramLogic.propInd] using      OracleComp.ProgramLogic.triple_support (oa := hr.gen)  · intro x    rcases x with pk, sk    by_cases hx : (pk, sk)  support hr.gen    · have hrel : rel pk sk = true := hr.gen_sound pk sk hx      simpa [OracleComp.ProgramLogic.propInd, hx] using        (OracleComp.ProgramLogic.triple_probOutput_eq_one          (oa := do            let (c, e)  σ.commit pk sk            let r  $ᵗ Chal            let s  σ.respond pk sk e r            pure (σ.verify pk c r s))          (x := true) (h := by simpa using hc pk sk hrel))    · simpa [OracleComp.ProgramLogic.propInd, hx] using        (OracleComp.ProgramLogic.triple_zero          (oa := do            let (c, e)  σ.commit pk sk            let r  $ᵗ Chal            let s  σ.respond pk sk e r            pure (σ.verify pk c r s))          (post := fun y => if y = true then 1 else 0))
Project
VCVio
License
Apache-2.0
Commit
2ceb2d825ee3
Source
VCVio/CryptoFoundations/FiatShamir/Sigma.lean:473-510

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