In August 2022, Solana Foundation engaged NCC Group to conduct a security assessment of the ZK-Token SDK, a collection of open-source functions and types that implement the core cryptographic functionalities of the Solana Program Library (SPL) Confidential Token extension. These functionalities are homomorphic encryption and associated proofs used to demonstrate the consistency of elementary instructions that move tokens between accounts while keeping the involved amounts in an encrypted format that ensures that only the sender and recipient may learn any information about these amounts.
