dalek-ed25519-verified/README.md
mrwulf 8ce599c4aa group-law layer: complete twisted Edwards addition law proven
Extraction widened to backend::serial::curve_models + edwards (own gen/,
209 defs). Adapted the reference Ed* proof suite: namespace rename +
Curve25519TraitsIdentity -> Curve25519_dalekTraitsIdentity. New opaque
externals (scalar_mul backends, get_selected_backend, decompress, sum,
from_slice) are axioms outside both certificate cones — verified by the
Phase-3 audit. All 21 proofs compile; field certificates unchanged.

Not claimed (matching the reference solution's honest scope): edAdd
associativity, scalar multiplication, decompress/compress, AVX2 backend.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-02 14:50:42 +02:00

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# 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 │ Scalar52 ops correct mod
├──────────────────────────────┤
│ 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 | `scalarImplementation` | ⏳ in progress | — |
| Signature (EdDSA) | `verifyEquation` | ⏳ in progress | — |
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
```
## 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).