ING Bank is continuing further down the path of advanced blockchain privacy with the release of its Zero-Knowledge Set Membership (ZKSM) solution, announced this week at the Sibos banking conference.
The Netherlands-based lender had already received plaudits for adapting classical zero-knowledge proofs (a way of proving possession of a secret without revealing the secret itself) into a simpler form for use within the bank called zero-knowledge range proofs.
Zero knowledge range proofs can prove a number is within a specific range. For example, a mortgage applicant could prove that their salary sits within a certain range without revealing the exact figure. As such range proofs are computationally lighter than regular zero-knowledge proofs and run faster on a blockchain.
Also designed to scale on a blockchain architecture, zero-knowledge set membership (ZKSM) allows for alphanumeric data to be validated within a specified set. In practice, this means moving beyond numbers into other types of data, such as proving dimensions and geographic positioning.
As an example, in a know-your-customer (KYC) check, a user can be validated to be part of a group (say, an EU citizen) without disclosing the exact country that he/she lives in. If the data set formed includes all countries in the European Union, and if the private information given is the country of residence of a user, the user can prove that he/she is an EU citizen.
Since being open-sourced, the body of cryptographic work that ING is building on has been subjected to academic to peer review by the likes of MIT's Madars Virza, one of the co-founders of zcash.
Annerie Vreugdenhil, head of wholesale banking innovation at ING, said launching ZKSM in an open-source capacity is the next step in the journey to figure out how to deal with data and privacy using distributed ledger technology (DLT).
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"At ING, we are fortunate to have some of the best minds in the industry working on our programme," said Vreugdenhil. "And we are excited that our ground-breaking solution is now ready to be implemented and tested."
Enigma machine image via Shutterstock