(from_bytes_mod_order_wide_spec, kernel-audited)
Proofs/ScalarPackSpec.lean:
- scalar52_to_bytes_spec: Scalar52::to_bytes (the PACK step - pure
bit-packing at radix 2^52, no reduction) serializes canonical limbs to
exactly their value: bytesVal s = scVal a. Second application of the
ToBytesSpec walk generator; boundary bytes 6 and 19 only (the two
non-byte-aligned 52j offsets), disjoint ORs to additions as before.
- from_bytes_mod_order_wide_spec: the verifier's k = SHA-512-to-scalar
entry composes from_bytes_wide_spec (the proven mod-l reduction) with
the pack: for 64 input bytes of value T, the returned Scalar's 32
bytes denote V with V < l and V = T (mod l) - precisely the scalar
premises vartime_double_base_mul_spec consumes (V < l < 2^253).
- byte_split_52_4: the offset-4 chunk split for 52-bit limbs; the five
ToBytesMath byte_split_* lemmas shed their unused 2^51 premises (pure
telescopes, valid for all f).
Both certificates exact-standard-three. Full button green fresh.
Half-lift remaining (mapped in memory): dsm dispatch wrapper, recompute
bind-chain inversion, bytesVal injectivity, assembly in PointLiftSpec.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
