Port BNB cryptographic hardening follow-ups#6
Open
mswilkison wants to merge 5 commits into
Open
Conversation
mswilkison
force-pushed
the
codex/remove-unused-protocols
branch
from
b366e27 to
3284c6b
Compare
Doc + small defensive-code follow-ups to the PR #2/#4/#5 review thread. None of these are security-blocking; they close out the cosmetic and pre-existing items that did not warrant their own PR earlier. - common/hash_utils.go: strengthen RejectionSample doc so the name does not mislead future readers — the function is modular reduction, not true rejection sampling, and the bias bound depends on q vs the hash width. - crypto/paillier/factor_proof.go: document that the tagged and legacy FactorChallenge paths emit different challenge distributions (positive-only vs signed), and note that FactorVerify's CmpAbs bounds exist to accommodate the legacy signed encoding. - tss/params.go: expand SetSessionNonceBytes docstring with the collision/uniqueness/entropy guidance reviewers asked for. - ecdsa/{keygen,signing}/rounds.go: document the round-1-capture invariant for getSSID so future refactors do not silently drift the hashed round.number domain separator. - crypto/ecpoint.go: flag SetCurve's in-place mutation in the doc comment; the chained-call style is a footgun on shared points. - crypto/vss/feldman_vss.go: reject nil shares, nil/zero share IDs, and duplicate IDs in ReConstruct before the Lagrange loop, so malformed inputs return an error instead of panicking through ModInverse(0). Add focused test coverage for each rejection path. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
mswilkison
force-pushed
the
codex/review-residual-cleanup
branch
from
fb8602e to
c9e9c09
Compare
The previous text stated the bias bound as `q / 2^eHash.BitLen()`, which
evaluates to ≈ 1 for secp256k1 and cannot support the docstring's own
≈ 2^-128 conclusion. The "q significantly smaller than 2^eHash.BitLen()
(e.g., q = 2^256)" example was also internally inconsistent (q = 2^256
is not smaller than 2^256).
Rewrite the paragraph to:
- State the safe regime as a property of q ("close to 2^k from below")
rather than via a loose formula or call-site enumeration.
- Drop the unused curve25519 reference whose conclusion is correct but
not derivable from the simple `r/M` bound.
- Cross-reference HashToN / HashToNTagged for the large-modulus regime
that they were introduced to address.
Documentation-only change. RejectionSample's behavior is unchanged
(LiterallyJustMod under the hood), so no computed challenge value moves.
piotr-roslaniec
approved these changes
May 23, 2026
mswilkison
changed the title
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
Stacked on #5. Ports the remaining BNB cryptographic hardening follow-ups into Threshold's secp256k1-only TSS stack.
GetRandomInt's zero-inclusive range, deterministic message wire bytes, and large-modulussampleYModNblock indexing.Compatibility
BREAKING: tagged Fiat-Shamir challenge inputs change proof transcripts. All operational nodes must upgrade in lockstep; mixed old/new proof verification is expected to fail.
Additional API/behavior changes:
ecdsa/signing.PrepareForSigningnow returns an error as its third return value.tss.NewParametersrejects party counts below 2, thresholds outside[1, partyCount), zero PartyID residues, and mod-q PartyID collisions.tss.SortPartyIDspanics on duplicate raw party keys instead of silently sorting invalid input.Downstream Check
threshold-network/keep-coreuses ofPrepareForSigning.threshold-network/keep-coreNewParameterscall sites use group-derived party sets; the visible test call site uses five parties.Validation
go test ./...go test ./common ./crypto/schnorr ./crypto/vss ./crypto/paillier ./ecdsa/keygen ./ecdsa/signing -run 'Test(GetRandomIntPreservesZeroInclusiveRange|Schnorr.*UnregisteredCurve|VerifyAllowsUnregisteredCurve|SampleYModNDeterministicAndSupportsManyBlocks|StoreMessage)'git diff --check