Files
proofs/lean/Crypto/MLDSA.lean
zooqueenandHanzo Dev d3bff5e2dc proofs: drive Lean library to 0 errors, eliminate proof-by-assumption axioms
The lean/ proof library (88 files) had ~180 type-check errors across ~45 files
plus 31 proof-by-assumption axiom cheats. It now type-checks cleanly under
Lean 4.14.0 + Mathlib, with every theorem genuinely proven from definitions.

Errors fixed:
- Stale Mathlib imports: Data.Nat.Basic / Data.Int.Basic were removed this rev
  -> Data.Nat.Defs / Data.Int.Defs (57 files).
- Shared AI/Agent/Governance/Contract/DeFi/Ecology draft files: same proof-rot
  as the zoo-labs sibling library (now reconciled): omega missing in-scope
  bounds, dead tactics after simp, simp over-reduction, doc-comment placement,
  reserved-word binders, deriving Repr on Finset-bearing structs, noncomputable
  defs over opaque primitives.
- Consensus/Liveness: collapsed a 74-error cascade (undefined shared state model
  inlined from Safety.lean; the |>. pipe-projection vs comparison parse trap on
  14 lines rewritten to explicit dot projection).
- Crypto (BLS/FROST/Corona/Hybrid/threshold/FHE), Consensus, Protocol, Warp,
  Trust, GPU, Compute, Network, DeFi: brought structure invariants into scope
  for omega, Nat-division bounds via Nat.div_le_of_le_mul / Nat.div_mul_le_self,
  noncomputable over opaque crypto ops, deriving Inhabited for index access.

Integrity:
- Removed all 31 `theorem X := X_ax` cheats (axiom asserting the identical
  statement) and proved each from definitions; removed the UNSOUND
  content_addressed axiom (hash-injectivity over a struct with free fields).
- Quorum-intersection theorems (BFT/Quasar/Flare/Warp/BLS/GPU/Bridge): the draft
  hypothesis 3f<n is insufficient (n unbounded above makes them false); tightened
  to the optimal-resilience invariant n=3f+1 / 2t>n. Statement intent preserved.
- Net axiom change: -35 / +1 (the one addition, honesty_static, is a
  fixed-validator-set modeling assumption matching sibling files).
- Remaining axioms are trusted-base only: opaque crypto primitives (groups,
  pairings, hardness, hashes, FHE encrypt/decrypt, BLS soundness, forward
  secrecy, Fisher-Yates uniformity) and protocol modeling assumptions. No
  sorry/admit/native_decide. Verified all theorems trace to
  [propext, Classical.choice, Quot.sound] plus those primitives.

Co-authored-by: Hanzo Dev <[email protected]>
2026-06-02 05:54:28 -07:00

83 lines
2.6 KiB
Lean4

/-
Authors: Antje Worring, Zach Kelling
ML-DSA (FIPS 204) Signature Correctness
Models the ML-DSA precompile (src/precompiles/mldsa/).
ML-DSA is the NIST post-quantum digital signature standard,
based on the Fiat-Shamir with Aborts paradigm over module lattices.
Maps to:
- src/precompiles/mldsa/: Go implementation
- luxfi/crypto: ML-DSA package
Properties:
- Correctness: sign then verify always succeeds
- EUF-CMA: existential unforgeability under chosen message attack
- Signature size: 3309 bytes for ML-DSA-65 (security level 3)
-/
import Mathlib.Data.Nat.Defs
import Mathlib.Tactic
namespace Crypto.MLDSA
/-- ML-DSA security levels -/
inductive SecurityLevel where
| level2 : SecurityLevel -- ML-DSA-44 (128-bit)
| level3 : SecurityLevel -- ML-DSA-65 (192-bit)
| level5 : SecurityLevel -- ML-DSA-87 (256-bit)
/-- Signature sizes by security level -/
def sigSize (l : SecurityLevel) : Nat :=
match l with
| .level2 => 2420
| .level3 => 3309
| .level5 => 4627
/-- Public key sizes -/
def pkSize (l : SecurityLevel) : Nat :=
match l with
| .level2 => 1312
| .level3 => 1952
| .level5 => 2592
/-- Abstract sign and verify functions for ML-DSA -/
axiom mldsa_sign : SecurityLevel → Nat → Nat → Nat
axiom mldsa_verify : SecurityLevel → Nat → Nat → Nat → Bool
axiom mldsa_correctness :
∀ (l : SecurityLevel) (sk pk msg : Nat),
-- For a valid key pair (sk, pk), sign then verify always succeeds
mldsa_verify l pk msg (mldsa_sign l sk msg) = true
/-- EUF-CMA security under Module-LWE assumption -/
axiom mldsa_euf_cma :
∀ (l : SecurityLevel) (pk msg : Nat) (forgery : Nat),
-- No PPT/quantum adversary can forge a signature on a new message
-- even after seeing signatures on chosen messages (Module-LWE hardness)
mldsa_verify l pk msg forgery = true →
∃ (sk : Nat), forgery = mldsa_sign l sk msg
/-- Signature size is bounded -/
theorem sig_size_bounded (l : SecurityLevel) :
sigSize l ≤ 5000 := by
cases l <;> simp [sigSize]
/-- ML-DSA-65 is the default for Lux (NIST Level 3, 192-bit security) -/
theorem default_level_3 : sigSize .level3 = 3309 := rfl
/-- Public key size at level 3 -/
theorem pk_size_level3 : pkSize .level3 = 1952 := rfl
/-- Security levels are ordered -/
theorem level2_lt_level3 : sigSize .level2 < sigSize .level3 := by simp [sigSize]
theorem level3_lt_level5 : sigSize .level3 < sigSize .level5 := by simp [sigSize]
/-- All signature sizes fit in a network packet (< 5KB) -/
theorem all_sigs_bounded : ∀ l : SecurityLevel, sigSize l < 5000 := by
intro l; cases l <;> simp [sigSize]
end Crypto.MLDSA