Transpile the Scalar52 limb backend (backend::serial::u64::scalar
add/sub/mul/square/montgomery_*) from Rust to Lean via Charon/Aeneas,
scoped at the function level to the iterator-free arithmetic core.
- verification/extract-scalar.sh: function-level Charon/Aeneas extraction
- verification/gen/CurveScalar/{Types,Funs}.lean: transpiled model (27 defs).
This fork (v4.1.2) implements Scalar52::sub's constant-time conditional add
with a pure arithmetic mask (constants::L[i] & underflow_mask), so the
extraction pulls in NO external functions or types (unlike v5 dalek, which
routes sub through subtle, and v4.1.3, which uses a local black_box).
- verification/gen/CurveScalar/{TypesExternal,FunsExternal}.lean: decl-free
stub modules kept so the check manifest is uniform across forks.
- verification/Proofs/ScalarDenote.lean: semantic foundation — Scalar52
denotation into ℤ/ℓℤ, limb-bound invariant, and L_val (the transpiled
constants::L denotes exactly the group order ℓ, kernel-checked).
- verification/check-scalar.sh: guarded compile of the gen modules plus the
denotation foundation.
check-scalar.sh passes: gen compiles; denotation + L = ℓ proven.
add/sub/mul remain in progress.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
