NPVDKGRS
Threshold distributed key generation and resharing. Open source under the Apache licence, built on the IETF BLS signature draft.
Research
What is proven, what is specified, and what is still open.
Foundations
Peer review
The key-management construction was reviewed by an independent university cryptography research group, informally, with positive findings.
Production
The scheme runs today inside two regulated institutions — an electronic money institution licensed by Lietuvos bankas, and a MiCA-authorised crypto-asset service provider (CASP) licensed and supervised by Latvijas Banka — with a threshold key on every customer account.
Where Pactena sits
A practical, deployable instantiation in the transferable e-cash line — Chaum–Fiat–Naor through to Bauer–Fuchsbauer–Qian. The contribution is not a new hardness assumption. It is that the transferable, identity-revealing, offline-capable construction is small enough and fast enough to run at a checkout, and that the provenance chain makes attribution precise rather than merely detectable.
Open questions
The protocol is fully specified, implemented and demonstrated.
- External cryptographic review of the payment layer is under way; the outcome will be published. The specification is complete.
- The post-quantum variant exists as an algorithmic design. Implementation is active work — this front is genuinely open.
- The offline transfer depth is a tunable design parameter, calibrated per deployment rather than fixed.
Architecture document
The architecture document sets out the network topology and the precise integration an issuing institution needs — the node it runs, the interfaces to core banking, and where responsibility begins and ends. Settlement beyond the existing rails is under specification, and the process is being standardised.
Shared under NDA
Collaboration
Review, joint publication and research consortium participation are all open.