ING is out to prove that startups aren't the only ones that can advance blockchain cryptography.Rather than waiting on the sidelines for innovation to arrive, the Netherlands-based bank is diving headlong into a problem that it turns out worries financial institutions as much as average cryptocurrency users. In fact, the bank first made a splash in November of last year by modifying an area of cryptography known as zero-knowledge proofs.
Simply put, the code allows someone to prove that they have knowledge of a secret without revealing the secret itself. On their own, zero-knowledge proofs were a promising tool for financial institutions that were intrigued by the benefits of shared ledgers but wary of revealing too much data to their competitors. The technique, previously applied in the cryptocurrency world by zcash, offered banks a way to transfer assets on these networks without tipping their hands or compromising client confidentiality. But ING has came up with a modified version called "zero-knowledge range proofs," which can prove that a number is within a certain range without revealing exactly what that number is. This was an improvement in part because it uses less computational power and therefore runs faster on a blockchain.
https://www.coindesk.com/banking-giant-ing-quietly-becoming-serious-blockchain-innovator/