TTP-Aided Secure Computation Using (k, n) Threshold Secret Sharing With a Single Computing Server

Secure computation can be divided into those using homomorphic encryption and secret sharing. The advantage of the former method is that the computation can be performed on a single computing server and the computation process can be made public if the encryption key used is securely managed. However, the latter is computationally light and capable of high-speed processing, but it requires multiple independently managed computing servers, and processes of
$k$
or more servers cannot be disclosed. When considering a business model for implementing secure computation that uses secret sharing, private information can be leaked if computing servers are managed by the same organization. Therefore, we need a complex business model in which multiple companies without conflicts of interest manage each computing server independently and make a profit. However, this approach is difficult to implement in practice. In this study, we proposed a secure computation using secret sharing. Moreover, by effectively using TTP, we demonstrated that it is possible to realize secure computation with a single computing server. In addition, we demonstrated that, if the security keys used are securely managed, the entire computational process can be made public. In other words, we realize a method that addresses all the drawbacks of the aforementioned methods, and it is possible to realize faster and more secure computations than conventional methods using secret sharing.