mrwulf
18abd45edb
Phases 3/3b establish what each certificate RESTS ON. Neither says what it SAYS, nor what it is ABOUT. A certificate gutted to a tautology of the same axiom cone passes both; so does one whose reference definition has been redefined to BE the extracted code, at which point the theorem reads `loop = loop` and every cone is byte-identical. Phase 3c closes that. Proofs/Audit.lean emits a canonical block holding the policy constants, every certificate's fully-elaborated statement (pp.all, so implicit arguments, instances and universe levels are visible), and the body of every specification constant transitively reachable from those statements. Its SHA-256 is pinned in check.sh and the block itself is committed as AUDIT-MANIFEST.txt, so a mismatch is DIFFED, not merely reported. 31 certificates, 68 specification constants per repository. Two tiers, not one. These forks have an arithmetic tier that must stay oracle-free and an apex tier carrying this fork's hash and wire-format axioms, and the apex boundary genuinely differs per fork (dalek 8 extra names, anza 4, risc0 and betrusted 5). One shared constant would have widened the arithmetic tier to accept hash oracles, which is the most valuable property these repos have. Each auditor is generated from its own repository's policy. Phase 0b pins the extracted model. This was not a precaution: risc0 and betrusted were observed emitting BYTE-IDENTICAL audit-manifest digests (6c821b8e…) while shipping demonstrably different extracted models, their point-doubling routines differing in operation order. A statement names an extracted function; it does not contain that function's body. Binding statements is not binding the subject. Membership derives from the filesystem, so a new model file fails closed. selftest-statements.sh attacks both phases with ten cases, each asserting a specific diagnostic: an edited model body, an unlisted model file, a widened policy, a hand-edited committed block, a certificate dropped from the auditor WITH the digest refreshed to match, and a gutted statement whose cone is unchanged. It lifts the phases out of check.sh at run time, so it attacks the shipping gate rather than a copy. Two bugs found and fixed during that testing, both mine: Phase 3c read `$0` after `cd "$AENEAS_LEAN"`, and $0 is the caller's relative path; and the axgate self-test compared the tree against a pristine checkout rather than against how it found it. A third expectation was wrong rather than the code — widening the apex boundary is caught by the exact-cone requirement before the digest ever runs, which is a stronger rejection, and the test now says so. All sixteen runs green at these commits: four main buttons, four axgate self-tests, four binding self-tests, four scalar buttons. TRUSTED-BASE.md records what this binds and, at equal length, what it does not: a digest binds identity, not meaning; an author can rotate the pins in one commit and is caught by review, not by the script; and pinning the model says nothing about whether Charon and Aeneas translated the Rust faithfully. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> |
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|---|---|---|
| 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).