mrwulf
a377ffc587
Canonicity pass (the layer is now closed under its own preconditions): - sub_val_spec post carries the exact value equation (exists beta <= 1, scVal r + scVal b = scVal a + ell*beta, with the underflow guard beta = 1 -> scVal a < scVal b) - add/montgomery_reduce/mul/aggregate posts all carry scVal r < ell: canonical inputs give canonical outputs everywhere. Needed because from_bytes_wide (hash-to-scalar) feeds Montgomery outputs into add. Hash-to-scalar foundation (toward Scalar::from_hash / EdDSA verify): - extraction scope + from_bytes_wide (brings constants::R); regenerated gen - source repos carry a documented Aeneas-compat patch: the bare `hi[4] = words[7] >> 20` extracts ill-typed at pin bf13c42e; masked (semantic no-op, words[7] >> 20 < 2^44) - Proofs/ScalarWideSpec.lean: R constant lemmas (R = 2^260 mod ell, witness 2^260 = R + 255*ell) and montgomery_mul_spec, the single Montgomery round: [r]*2^260 = [a]*[b], canonical bounded output check-scalar.sh: 10 proof files, 11 kernel audits, all exactly [propext, Classical.choice, Quot.sound]. Button pressed fresh: green. |
||
|---|---|---|
| verification | ||
| .gitignore | ||
| README.md | ||
| TRUSTED-BASE.md | ||
betrusted-ed25519-verified
Formal verification of the ed25519 implementation in betrusted-io/curve25519-dalek (Precursor/Xous fork, v4.1.2), built as a coherent proof pyramid in Lean 4 via the Charon/Aeneas transpilation pipeline:
┌──────────────────────────────┐
│ Signature (EdDSA verify) │ accepted ⇒ [8][S]B = [8]R + [8][k]A
├──────────────────────────────┤
│ Scalar arithmetic mod ℓ │ Scalar52 ops correct mod ℓ
├──────────────────────────────┤
│ Group law (twisted Edwards) │ point ops = complete addition law
├──────────────────────────────┤
│ Field 𝔽_p, p = 2²⁵⁵ − 19 │ FieldElement51 ops correct mod p
└──────────────────────────────┘
Every layer states its theorems about the actual Aeneas-transpiled Rust
code (never about a hand-written re-model), and every claim in the status
table below is backed by a compiled proof plus an axiom audit of the named
certificate. Files that do not compile under verification/check.sh are not
in this repository.
Layer status
| Layer | Certificate | Status | Axioms of certificate |
|---|---|---|---|
| Field 𝔽_p | fieldImplementation |
✅ proven | [propext, Classical.choice, Quot.sound] |
| Group law (Edwards) | edwardsImplementation |
✅ proven | [propext, Classical.choice, Quot.sound] |
| Scalar mod ℓ | scalarImplementation (add ✅ sub ✅ mul ✅) |
✅ proven | [propext, Classical.choice, Quot.sound] |
| Signature (EdDSA) | verifyEquation (planned) |
⏳ planned | — |
Status legend: ✅ proven & axiom-audited · ⏳ in progress · ❌ not started.
This table is updated only when verification/check.sh passes for the layer.
Source
- Upstream: betrusted-io/curve25519-dalek, commit
16e087a - Pinned/patched source: saymrwulf/betrusted-curve25519-dalek-source, commit
64ee8f0 - Patches: minimal Aeneas-compatibility only (documented in the source repo)
- Scope caveat: this verifies the fork's pure-Rust
serial/u64path. The Engine25519 hardware-accelerator path on Precursor is different code and is NOT covered by these proofs.
Toolchain (pinned)
| Component | Version |
|---|---|
| Aeneas | bf13c42e |
| Charon | 9dd7f23c |
| Lean | v4.30.0-rc2 |
| OCaml | 5.3.0 |
Reproducing
source ~/aeneas-toolchain/env.sh
cd verification
./extract.sh # Rust → LLBC → Lean (regenerates gen/)
./check.sh # compiles EVERY shipped file + axiom-audits EVERY certificate
The scalar layer has its own pair of buttons:
./extract-scalar.sh # regenerates gen/CurveScalar (Scalar52 limb arithmetic)
./check-scalar.sh # compiles the scalar gen + the proven scalar foundation
Trusted base
See TRUSTED-BASE.md for the complete list of assumptions (Lean kernel, mathlib, Charon/Aeneas semantics, external-function models, and — in the signature layer only — an opaque SHA-512 model).