Gen merge: extract.sh now co-extracts the Scalar52 backend and the public
scalar::from_bytes_mod_order[_wide] conversions into the SAME CurveField
model, so the whole library — field, curve_models, edwards, scalar — shares
one type universe (Scalar is a single structure, not two). The scalar proof
chain repoints by one import line (ScalarDenote: CurveScalar.Funs ->
CurveField.Funs); check-scalar.sh's gen list follows. Both buttons — the
scalar certificates and the field/group/dsm certificates — pass fresh over
the merged gen, so the merge is proven-safe, not merely hoped-safe.
Verify glue (gen/CurveSig): the extracted ed25519-dalek verify_sha512 path,
integrated against the proven model:
- TypesExternal.lean imports CurveField.Types, so CompressedEdwardsY /
EdwardsPoint / Scalar in the glue ARE the proven model's types. Only the
genuinely foreign types stay opaque: sha2.Sha512, ed25519.Signature,
signature.error.Error.
- FunsExternal.lean imports CurveField.Funs, so every curve/scalar call
(compress, vartime_double_scalar_mul_basepoint, as_bytes, neg,
from_bytes_mod_order[_wide]) resolves to a proven definition — no axioms.
The `?`-operator plumbing (Try::branch, FromResidual::from_residual) and
compressed_from_bytes get real definitions. Only the SHA-512 hasher
(sha512_new/update/finalize_bytes) and two opaque wire accessors
(Signature.to_bytes, Error.new) remain axiomatized — the deliberate,
documented hash-oracle boundary.
Audited: `verify_sha512`'s entire axiom cone is
[propext, Classical.choice, Quot.sound,
sha2.Sha512, sha512_new, sha512_update, sha512_finalize_bytes,
ed25519.Signature.to_bytes, signature.error.Error.new]
— zero curve axioms, zero scalar axioms. The verify path is definitionally
grounded in the certified model; the only trust boundary is SHA-512.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
