Described is a system for improving data authentication using blockchain technology and multi-party computation (MPC). The system ensures authenticity of distributed data sent from one or more servers to the distributed clients. The system initializes MPC protocols to ensure secrecy of keys used to sign a new data element. Blockchain technology is utilized to ensure correctness and integrity of the new data element. A bidirectional blockchain is used such that a forward blockchain stores the new data element to be received by the distributed clients, and a reverse blockchain stores a public key used by the distributed clients to verify authenticity of the new data element stored in the forward blockchain. Signing of the new data element with the public key causes a previous public key to expire.