mrwulf
fc495453ff
`Proofs/SigApexSpec.lean`:
- `verify_loop_full` — the extracted 32-byte comparison loop returns exactly
the byte-equality of the two arrays (induction; axiom cone = exactly
[propext, Classical.choice, Quot.sound]).
- `verify_accepts_iff` — THE APEX: for a signature that parses, the
extracted RustCrypto verifier accepts IFF the recomputed compressed point
compress( [s]·B − [k]·A )
equals the signature's R byte-for-byte. The recomputation is grounded in
the PROVEN curve model (every curve and scalar call is a certified
definition); k is whatever scalar the SHA-512 oracle produces — the
honest EdDSA acceptance criterion with the hash opaque.
Boundary hygiene forced by the audit itself:
- The public vartime_double_scalar_mul_basepoint dispatch pulled the AVX2
vector-backend axiom into the apex cone. Fixed at the build level:
extract.sh pins RUSTFLAGS --cfg curve25519_dalek_backend="serial", so the
SIMD arm compiles out; BackendKind has only Serial and
get_selected_backend becomes a real definition (ok Serial).
- subtle.Choice.unwrap_u8 upgraded from axiom to the documented model
definition (Choice := U8; unwrap_u8 = self.0) — it sits on the verify
path via compress → is_negative.
- CurveSig modules added to GEN_MODULES (stale-olean incoherence otherwise).
check.sh grows Phase 3b: the apex certificate's axiom cone must equal
EXACTLY
[propext, Classical.choice, Quot.sound,
ed25519.Signature, sha2.Sha512,
sha512_new, sha512_update, sha512_finalize_bytes,
ed25519.Signature.to_bytes, signature.error.Error, Error.new]
— the SHA-512 hash oracle plus the opaque wire-format types. NO curve
axioms, NO scalar axioms, NO backend axioms, enforced on every button press.
Full check.sh green: 16 standard certificates + the apex audit.
Phase 2 (the point-level equation [s]B − [k]A = decompress R, needing
to_bytes canonicity and decompress) remains deferred and documented.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
|
||
|---|---|---|
| verification | ||
| .gitignore | ||
| README.md | ||
| TRUSTED-BASE.md | ||
dalek-ed25519-verified
Formal verification of the ed25519 implementation in dalek-cryptography/curve25519-dalek (upstream, v5.0.0-rc.1), 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: dalek-cryptography/curve25519-dalek, commit
4cf8db2 - Pinned/patched source: saymrwulf/curve25519-dalek-source, commit
135ed70 - Patches: minimal Aeneas-compatibility only (documented in the source repo)
- Verified backend:
backend/serial/u64(FieldElement51,Scalar52). SIMD/AVX backends are out of scope (marked opaque).
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 + all scalar proofs (add, sub,
# Montgomery mul) and kernel-audits 10 certificates,
# including the scalarImplementation aggregate
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).
Provenance
Proof engineering in this repository builds on the verification methodology and proof architecture of PlanetMacro/ed25519-verificationtest (the reference solution). All proofs here are checked against this fork's own extracted code; nothing is claimed that the check script does not compile.