Securely replicating authentication services

A framework for designing a type of distributed authentication protocol is given, whose security and availability are higher compared to those of centralized ones. It uses the technique of secret sharing and introduces a cross checksum scheme to achieve secure replication. Fewer than a certain number of malicious servers cannot damage security except by causing denial of service, and this only happens when too many honest servers accidentally fail at the same time. The protocol is suited to an environment where no trustworthiness of any server is permanently guaranteed. The approach is general enough not to rely on any particular authentication protocol. Existing implementations need minor modification. Only a short piece of code is needed to run the implementations as many times as required. Hence, different centralized protocols can be incorporated into one distributed protocol.<>