Development of a method for hiding private data for a blockchain-based tender system

A tender system has been developed based on the Ethereum open blockchain platform that allows to hide the information about applications at the request for proposals stage. A new method has been created to solve the problem of information privacy in open blockchain systems using the zk-SNARK, cryptographic zero-knowledge proof protocol. The proposed method has been implemented as a cryptographic scheme based on the libsnark library. To integrate the cryptographic scheme into the system, the Ethereum C++ client has been modified — a new tenderzkp module has been added. It implements functions for creating and verifying zk-SNARK proofs. Interaction with the implemented cryptographic scheme from the smart contract codes is carried out through the new added precompiled contracts. A Solidity library has been created to work with these contracts. The JSON-RPC API of the Ethereum C++ client has been expanded to enable to call methods of the cryptographic scheme from third-party applications.