saymrwulf/betrusted-ed25519-verified
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Author SHA1 Message Date
mrwulf
a377ffc587 Signature layer, first bricks: canonicity closure + hash-to-scalar foundation 
Canonicity pass (the layer is now closed under its own preconditions):
- sub_val_spec post carries the exact value equation
  (exists beta <= 1, scVal r + scVal b = scVal a + ell*beta, with the
  underflow guard beta = 1 -> scVal a < scVal b)
- add/montgomery_reduce/mul/aggregate posts all carry scVal r < ell:
  canonical inputs give canonical outputs everywhere. Needed because
  from_bytes_wide (hash-to-scalar) feeds Montgomery outputs into add.

Hash-to-scalar foundation (toward Scalar::from_hash / EdDSA verify):
- extraction scope + from_bytes_wide (brings constants::R); regenerated gen
- source repos carry a documented Aeneas-compat patch: the bare
  `hi[4] = words[7] >> 20` extracts ill-typed at pin bf13c42e; masked
  (semantic no-op, words[7] >> 20 < 2^44)
- Proofs/ScalarWideSpec.lean: R constant lemmas (R = 2^260 mod ell,
  witness 2^260 = R + 255*ell) and montgomery_mul_spec, the single
  Montgomery round: [r]*2^260 = [a]*[b], canonical bounded output

check-scalar.sh: 10 proof files, 11 kernel audits, all exactly
[propext, Classical.choice, Quot.sound]. Button pressed fresh: green.
 2026-07-03 23:18:34 +02:00
mrwulf
1bbc70e5ce Scalar layer complete: Montgomery reduction + full mul ported, scalarImplementation aggregate 
Port of the dalek Montgomery stack against THIS fork's own extraction
(gen sections byte-identical, proofs recompiled from scratch here):
- Proofs/ScalarMulSpec.lean      - mul_internal: 9 exact schoolbook columns
- Proofs/ScalarMontSpec.lean     - part1/part2 exact-division rounds
  (LFACTOR*L0 = -1 mod 2^52), head/tail telescopes, mont_bound, tail walk
- Proofs/ScalarReduceSpec.lean   - montgomery_reduce main walk:
  scDenote r * 2^260 = Z in ZMod ell + 52-bit output bounds
- Proofs/ScalarFullMulSpec.lean  - mul = double Montgomery round through
  RR = R^2 mod ell; R cancelled as a unit; post: [mul a b] = [a]*[b]
- Proofs/ScalarMain.lean         - scalarImplementation aggregate (ScBnd
  interfaces; canonical inputs discharge the Montgomery bound)

sub_val_spec/add_val_spec posts strengthened with result-limb bounds.
check-scalar.sh: 9 proof files, 10 kernel audits, all exactly
[propext, Classical.choice, Quot.sound]. Button pressed fresh: green.
 2026-07-03 21:46:57 +02:00
saymrwulf
422e91f270 scalar layer: add+sub fully proven mod l against THIS fork's v4 extraction 
This v4.1.x fork implements Scalar52::sub with TWO loops (loop0 = borrow
chain; loop1 adds L &&& underflow_mask — the arithmetic-mask constant-time
conditional), a genuinely different code path from upstream v5's
subtle-based conditional_add_l. Verified per R2 against this fork's own gen:

- sub_loop_spec (= loop0): borrow chain, verbatim technique from dalek
- sub_loop1_zero_spec / sub_loop1_one_spec: the masked-L add, both mask
  values (0 / 2^64-1), full carry chains
- sub_val_spec: denote(sub a b) = denote a - denote b in ZMod l; the
  underflow mask um = ((borrow>>>63) XOR 1) - 1 resolved per case
- add_loop_spec + add_val_spec: denote(add a b) = denote a + denote b
  (v4 add_loop extracts token-identical to v5; composition through this
  fork's own sub_val_spec)

check-scalar.sh: full manifest, 5/5 kernel axiom audit
[propext, Classical.choice, Quot.sound], green at 300-400s/4096MB.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
 2026-07-03 18:45:17 +02:00