mirror of
https://github.com/saymrwulf/dalek-ed25519-verified.git
synced 2026-09-05 20:30:58 +00:00
saymrwulf
09fe47c59d
sub_val_spec closes the top-level two-clause value spec: denote(Scalar52.sub a b) = denote(a) - denote(b) in ZMod l for limb-bounded inputs with canonical subtrahend (scVal b < l). Axiom-clean [propext, Classical.choice, Quot.sound]; no sorry. The assembly documented-as-remaining last session is now done. Key resolutions: - Applied the WP "spec_bind" rule manually instead of "step", and reduced the resulting "let (difference,borrow) := (dw,w)" Prod-let with an explicit "show" — this was the destructuring friction that blocked the earlier attempt (step's arity heuristics mis-typed the pair result). - Inlined the subtle "Choice::from" identity (no step-spec, like csel_step). - PERFORMANCE: kept "scLimbs" as opaque atoms in the gamma5=1 derivation instead of "unfold ... at *" — the unfold exploded omega with 2^52..2^260 coefficients and blew past 600s; atomic form proves in ~1 min (METHOD 4, same kernel-cost discipline as the field layer). - The 2^260 borrow-wrap and the +l conditional-add cancel in ZMod l: beta5=0 direct; beta5=1 forces top carry gamma5=1 from scVal b < l, closed by linear_combination over the two telescopes (sub_telescope, add_telescope). check-scalar.sh: sub_val_spec in the manifest + Phase-3 audit (4/4 clean); proof-phase caps raised to 600s/8192MB for the assembly; full button green. exponentiation.threshold raised to 300 for the 2^260 literal. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
81 lines
3.9 KiB
Markdown
81 lines
3.9 KiB
Markdown
# 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` (planned; `sub_val_spec` ✅, `L_val`, loop specs proven) | 🔨 sub done · add/mul next | denotation + L=ℓ + FULL sub (⟦sub a b⟧=⟦a⟧−⟦b⟧ in ZMod ℓ) proven; add & Montgomery mul next |
|
||
| 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](https://github.com/dalek-cryptography/curve25519-dalek), commit `4cf8db2`
|
||
- **Pinned/patched source**: [saymrwulf/curve25519-dalek-source](https://github.com/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
|
||
|
||
```bash
|
||
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:
|
||
|
||
```bash
|
||
./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](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](https://github.com/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.
|