mrwulf
9eb3beabc4
Phase 1's anti-smuggling check reads source text. Measured today on Lean
v4.30.0-rc2, four distinct declarations compile cleanly and slip past its
anchored pattern:
` axiom cheat : ...` one leading space
`@[simp] axiom cheat : ...` line starts with the attribute
`unsafe axiom cheat : ...` `unsafe` absent from the modifier list
`axiom` <newline> ` cheat` no space follows the keyword
Any of them yields a repository that proves False while the button prints
ALL GREEN. Only the tab variant is blocked, and by Lean, not by us.
Hardening the pattern would fix the exhibited syntax rather than the class,
which is the mistake this estate has made before. Phase 2b stops parsing text
and asks the kernel instead: it reads every compiled Proofs/*.olean with
readModuleData and rejects any declaration that is an axiom.
Design notes:
- reads compiled artifacts rather than importing the modules, because
Proofs.Basic and Proofs.ConstSpecs deliberately reuse `zero_spec` and a
whole-corpus import is impossible by construction;
- membership is self-deriving from the filesystem, so Scalar* and
AxiomCheck are covered too — both are skipped by the CERTS audit and by
the dead-file gate;
- fails closed on absence: a missing .olean would make the scan vacuous, so
the count of compiled modules must equal the count of shipped sources;
- removes its temp source AND artifact on both paths, since a bare `rm`
after the call never runs under `set -e` when the gate goes red — exactly
how this repo accumulated 101 orphan .olean files;
- ~3 s for the whole corpus, against ~53 s for one module-importing run.
Phase 1's grep stays as a fast first line of defence. Phase 2b is the gate
that is load-bearing.
selftest-axgate.sh attacks the shipping gate, lifted out of check.sh at run
time rather than copied. It asserts the specific diagnostic, so a rejection
for an unrelated reason fails too, and it was itself negative-tested: with
the gate's throwError removed, the self-test goes red on exactly that case.
No proof, statement, specification or certificate is touched. No attested
commit is altered — the log binds specific commit hashes, all of which remain
ancestors of HEAD.
Co-Authored-By: Claude Opus 4.8 <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 ⇔ decompress(R) = [k](−A)+[s]B
├──────────────────────────────┤
│ 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) | verify_accepts_iff … verify_accepts_iff_decompress (4 tiers) |
✅ proven (phases 1+2) | standard three + the button-enforced SHA-512/wire-format boundary — see The signature apex |
Status legend: ✅ proven & axiom-audited · ⏳ in progress · ❌ not started.
This table is updated only when verification/check.sh passes for the layer.
The signature apex (phases 1 and 2)
The byte-level apex certificate CurveFieldProofs.verify_accepts_iff is the
literal EdDSA acceptance criterion, proven about the extracted verifier:
For a signature that parses, the verifier returns
Ok(())iff the recomputed compressed pointcompress([s]·B − [k]·A)equals the signature'sR, byte-for-byte — wherekis whatever scalar the opaque SHA-512 oracle produces from(R, A, msg).
The recomputation runs entirely through the proven model: the vendored ed25519-dalek verify glue is extracted as gen/CurveSig, whose
hand-maintained externals import gen/CurveField — every curve and scalar call
resolves by fully-qualified name to a proven definition. Only SHA-512 (three
stateful wrapper calls) and the wire-format types stay opaque.
check.sh has a dedicated audit phase (Phase 3b) that fails the build unless
the apex certificate's axiom cone is exactly
[propext, Classical.choice, Quot.sound] + {ed25519.Signature, sha2.Sha512, verifying.sha512_new, verifying.sha512_update, verifying.sha512_finalize_bytes, ed25519.Signature.to_bytes, signature.error.Error, signature.error.Error.new}
— i.e. the three Lean foundations plus the documented SHA-512/wire-format
boundary. Zero curve, scalar, or backend axioms. The companion certificate
verify_loop_full (the 32-byte comparison loop computes array equality)
carries the standard three axioms only.
Phase 2 (complete): the point-level lift. Phase 3b enforces the SAME axiom boundary on three further tiers that lift the byte equation to points:
| Tier | Certificate | Statement |
|---|---|---|
| half-lift | verify_accepts_iff_point |
accepted ⇔ R = the canonical encoding of [k]·(−A) + [s]·B (compress semantics + to_bytes canonicity + hash-to-scalar, recompute chain inverted) |
| point equation | verify_accepts_iff_point_eq |
for any valid on-curve Q canonically encoded by R: accepted ⇔ Q = [k]·(−A) + [s]·B as points (encoding-injectivity: d non-square + parity root-selection) |
| full lift | verify_accepts_iff_decompress |
R decompresses to a valid on-curve Pt, and accepted ⇔ Pt = [k]·(−A) + [s]·B — the constructive capstone |
The full lift runs through the extracted CompressedEdwardsY::decompress
itself, proven end-to-end: from_bytes parses the y-residue exactly below
bit 255 (from_bytes_spec), sqrt_ratio_i returns the even square root of
(y²−1)/(dy²+1) (sqrt_ratio_i_sq_spec, Fermat-exponent square root), and
the sign bit selects the x-parity (decompress_of_canonical, standard three
axioms). Byte comparison ↔ encoding equality ↔ point equality ↔
decompressed-point equality: every link is machine-checked over the
extracted code, and check.sh fails the build if any of the four tiers'
cones deviates from the boundary above.
Source
- Upstream: dalek-cryptography/curve25519-dalek, commit
4cf8db2 - Pinned/patched source: saymrwulf/curve25519-dalek-source, commit
aa0f6ab(adds the decompress step_2 negate-then-assign patch) - 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 gen model is ONE merged universe (gen/CurveField: field + curve +
scalar + the verify path's reachable code), regenerated in full by
extract.sh. The scalar layer keeps its own check button:
./check-scalar.sh # compiles the merged gen + all scalar proofs (add, sub,
# Montgomery mul, byte-parsing) and kernel-audits the
# scalar certificates, incl. 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).