fix(dwallet-mpc): deterministic internal-presign session identifiers across validators#1733
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…dators Internal presign sessions get their sequence number from a single shared counter, assigned in iteration order over (network key id) x (curve) x (signature algorithm), and the sequence number is bound into the session identifier transcript. Both iteration sources were unordered: - SUPPORTED_CURVES_TO_SIGNATURE_ALGORITHMS_TO_HASH_SCHEMES was a HashMap<u32, HashMap<u32, Vec<u32>>> — iteration order is random per process (RandomState), so each validator walked curves/algorithms in a different order; - the agreed network key ids were iterated straight off a HashMap. Each validator therefore derived *different* session identifiers for the same (curve, algorithm) work. Those sessions could never reach quorum, so they never completed, and the instantiated != completed gate then blocked that algorithm's pool top-ups for the entire epoch. Once a user presign request locked onto the starved pool, the EndOfPublish condition was unsatisfiable and the epoch could not advance. Observed live: in a 4-validator run the validators logged three distinct top-up orders, and exactly the sequence numbers whose (curve, algorithm) assignment happened to agree on 3+ validators completed — the rest hung forever, the ECDSA pool stayed empty all epoch, and the run timed out. A previous green run was a per-process-seed coin flip. Fix: BTreeMap at both nesting levels of the static, and collect the agreed key ids into a BTreeSet before the instantiation loop. Pre-existing bug from the internal sessions instantiation logic (#1638), not specific to this branch. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Jun 11, 2026
# Conflicts: # crates/ika-core/src/dwallet_mpc/mpc_manager.rs
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The bug
Internal presign sessions draw their sequence number from a single shared counter, assigned in iteration order over (network key id) × (curve) × (signature algorithm) — and that sequence number is bound into the session identifier transcript. Both iteration sources were unordered:
SUPPORTED_CURVES_TO_SIGNATURE_ALGORITHMS_TO_HASH_SCHEMESwas aHashMap<u32, HashMap<u32, Vec<u32>>>— iteration order is random per process (RandomState), so each validator walked curves/algorithms in a different order;HashMap.Each validator therefore derived different session identifiers for the same (curve, algorithm) work. Those sessions can never reach quorum, never complete, and the instantiated≠completed gate then blocks epoch advance.
The fix
Make both iterations deterministic (
BTreeMap/ sorted ids) so every validator assigns the same sequence numbers to the same work, producing identical session identifiers.Cherry-picked from
feat/ika-upgrade-test(29e8a09), where the cross-binary churn and v1.1.8 upgrade rehearsals run green with it.🤖 Generated with Claude Code