fips205-slhdsa-verified/verification
mrwulf e3f68b2473 phase 2: FIFTH CERTIFICATE — FORS pk-from-sig (Algorithm 17), inner + outer loops
Two theorems, split into two files (METHOD-4 discipline — each proof a clean
unit). NB: an early single-file/bare-rfl attempt appeared to "OOM at the clamp",
but that memory pressure was a SYMPTOM of the runaway whnf diagnosed below, not
a real memory need — the fixed proofs compile in seconds at the default caps.

fips205.fors_inner_loop_eq (Proofs/ForsInnerSpec.lean): the extracted inner
Merkle auth-path loop for ONE FORS tree (fors_pk_from_sig_free_loop0_loop0)
equals the explicit auth-path fold — at level j set tree height j+1, test bit j
of THIS tree's leaf index indices[i], hash the current node with auth.tree[j] in
the bit order (even: node||auth[j]; odd: auth[j]||node), halving the tree index.
Structurally the XMSS auth-path loop, but the bit source is indices[i]>>j and the
loop returns the (adrs,node) pair. Cone: kernel-3 + verify_mono.oracle.h.

fips205.fors_outer_loop_eq (Proofs/ForsOuterSpec.lean): the extracted outer
per-tree loop (fors_pk_from_sig_free_loop0) equals the explicit K-tree fold — for
each tree i, compute the leaf with F at tree index (i<<a)+indices[i], run the
inner Merkle loop over the A levels, write the result to root[i]. Consumes the
inner loop as an opaque sub-call. Cone: kernel-3 + verify_mono.oracle.{f,h}
(F per leaf; H transitively through the inner loop).

Fidelity review at authorship (three-way, both loops): extracted bodies (gen
Funs.lean 893-933 inner, 954-985 outer) == Rust verify_mono.rs
fors_pk_from_sig_free (verbatim from upstream fors.rs, hash calls -> oracle) ==
FIPS 205 Algorithm 17, incl. the even/odd sibling order and the (i<<a)+indices[i]
leaf index.

Proof: the branched-Merkle recipe (XMSS) for the inner loop (by_cases on the
index bit, pair-bind matcher made concrete via bind_congr+rintro then full simp);
the HT straight-line recipe for the outer loop, adapted (bind_congr-peeled step
lemma + bind_congr x16 induction, both threading the inner-loop sub-call opaquely). loop_unfold_bind / u32_succ
/ fwd_succ / hnext reused verbatim from ChainSpec.

check.sh: PROOFS += ForsInnerSpec, ForsOuterSpec; CERTS += the two fors certs;
audit imports both; check.sh settings unchanged (400s/4096MB). ForsOuterSpec
compiles in 4.4s / 2.4GB after the fix below. check.sh green over ALL SIX
certificates with the axiom audit. README status -> FIVE certificates.

DIAGNOSIS NOTE (honesty): ForsOuterSpec's fors_outer_step first closed with a
bare `rfl`, which whnf'd the whole 16-bind body INCLUDING the inner-loop `loop`
term and hit a DETERMINISTIC 4M-heartbeat timeout (never actually passed — an
earlier "green" reading was a misread wrapper exit code; the real error was
hidden by check.sh piping per-file output to /dev/null). Fix: peel the 16 binds
with bind_congr so the closing rfl only sees the small loop-tail, and close the
post-pair-rintro tail with a full simp (the pair `let` won't iota via simp only).
This is the HtSpec straight-line recipe adapted for a body that nests a loop.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-23 23:57:27 +02:00
..
gen/SlhVerify phase 2: FOURTH CERTIFICATE — hypertree layer walk (Algorithm 12) + de-plumbing 2026-07-23 17:14:21 +02:00
Proofs phase 2: FIFTH CERTIFICATE — FORS pk-from-sig (Algorithm 17), inner + outer loops 2026-07-23 23:57:27 +02:00
check-selftest.sh post-flip drill over the WOTS+ certificate: HELD; one rotted gate fixed 2026-07-23 15:07:07 +02:00
check.sh phase 2: FIFTH CERTIFICATE — FORS pk-from-sig (Algorithm 17), inner + outer loops 2026-07-23 23:57:27 +02:00
drill.sh drill: the post-flight drill becomes a button (drill.sh) 2026-07-23 15:36:00 +02:00
extract.sh audit catch 2: the oracle boundary is FIVE, not six 2026-07-22 23:02:40 +02:00
lean-guard SLH-DSA (FIPS 205) campaign skeleton: honest zero-certificate state 2026-07-22 21:00:57 +02:00