mirror of
https://github.com/saymrwulf/betrusted-ed25519-verified.git
synced 2026-09-04 20:24:08 +00:00
mrwulf
5a9d4237dd
Adds one item naming what check.sh Phase 2b binds — every compiled Proofs/*.olean, kernel-side, membership self-derived, fail-closed on a missing module — and, more importantly, what it still does not bind: declarations, not statements. A theorem gutted to a tautology with the same axiom cone passes every phase. Reading the statements remains a human act, and this document is where that has to be said rather than left for a reviewer to discover. Verified green at this commit's parent across all eight buttons on 2026-07-28; see formal-verification-control/RECORDED-RUN-2026-07-28.md. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
55 lines
3.6 KiB
Markdown
55 lines
3.6 KiB
Markdown
# Trusted base
|
||
|
||
What you must believe for the theorems in this repository to transfer to the
|
||
running Rust code. Everything else is machine-checked.
|
||
|
||
1. **Lean 4 kernel** (v4.30.0-rc2) and its three foundational axioms
|
||
`[propext, Classical.choice, Quot.sound]`. Every certificate is
|
||
`#print axioms`-audited against exactly this list.
|
||
2. **mathlib** (prebuilt oleans fetched by `lake exe cache get`).
|
||
3. **Charon + Aeneas** (pinned `9dd7f23c` / `bf13c42e`): the translation
|
||
from Rust MIR to the Lean model is assumed faithful. The generated
|
||
`gen/` files are never edited (comments only); proofs are stated ABOUT them.
|
||
4. **External-function models** (`gen/*/FunsExternal.lean`): Rust items that
|
||
Aeneas cannot translate (constant-time `subtle` primitives, iterator
|
||
plumbing, formatting) are axiomatized as opaque symbols. The axiom audit
|
||
proves none of these axioms enters the dependency cone of any certificate,
|
||
except where a model is explicitly listed below.
|
||
5. **The signature-apex boundary (signature layer only)**: FOUR apex-tier
|
||
certificates — `CurveFieldProofs.verify_accepts_iff` (byte apex:
|
||
accepted iff compress([s]·B − [k]·A) = R byte-for-byte),
|
||
`verify_accepts_iff_point` (half-lift: R is the canonical encoding of
|
||
the recomputed point), `verify_accepts_iff_point_eq` (point equation:
|
||
canonically-encoded Q accepted iff Q equals the recomputed point), and
|
||
`verify_accepts_iff_decompress` (full lift: R decompresses to a valid
|
||
on-curve point that equals the recomputed point) — are each
|
||
`#print axioms`-audited by check.sh Phase 3b against EXACTLY the
|
||
standard three plus this documented set, and the build fails on any
|
||
deviation:
|
||
`ed25519.Signature` (wire-format type), the single SHA-512 oracle
|
||
`verifying.sha512_hash3` (semantically `Sha512(R ‖ A ‖ msg)`),
|
||
`ed25519.Signature.to_bytes`, and `signature.error.Error`/`Error.new`
|
||
(opaque error type). The hash is an oracle with no algebraic properties
|
||
assumed — the theorems hold for whatever bytes it produces; the SHA-512
|
||
implementation itself is NOT verified. Zero curve, scalar, or backend
|
||
axioms are in any of the four cones. The constructive decompress theorem underneath the full lift
|
||
(`decompress_of_canonical`) carries the standard three axioms ONLY.
|
||
6. **Compilation of Rust to machine code** (rustc backend) is out of scope,
|
||
as is side-channel behaviour (timing, speculation). The proofs are about
|
||
functional correctness at the MIR/LLBC level.
|
||
7. **What the axiom gate binds, and what it does not.** `check.sh` Phase 2b
|
||
reads every compiled `Proofs/*.olean` and fails the build if any
|
||
declaration there is an axiom. It asks the kernel rather than parsing
|
||
source text, because the source-text check in Phase 1 is evadable four
|
||
ways — an indented `axiom`, `@[simp] axiom`, `unsafe axiom`, and `axiom`
|
||
with the name on the following line all compile and all miss its pattern.
|
||
Membership self-derives from the filesystem, so `Scalar*` and `AxiomCheck`
|
||
are covered as well, and the count of compiled modules must equal the
|
||
count of shipped sources, so a deleted `.olean` cannot make the scan pass
|
||
vacuously. `selftest-axgate.sh` attacks the shipping gate rather than a
|
||
copy of it, and was itself negative-tested by removing the gate's error.
|
||
**The residue you must still supply yourself:** this binds *declarations*,
|
||
not *statements*. Nothing in the button establishes that a certificate's
|
||
theorem says what its name — or this document — suggests it says. A
|
||
theorem gutted to a tautology with the same axiom cone would pass every
|
||
phase. Reading the statements remains a human act.
|