Enhancing security for two-party comparison over encrypted data
Ching‐Nung Yang, Zong-Xuan Yeh, Shen-Chieh Hsu, Zhangjie Fu · 2016
The so-called Yao's millionaire problem (YMP) is about securely comparing two numbers held by two parties, respectively. After comparison, the actual values of these two numbers are still unknown to both parties. Recently, Kaghazgaran and Sadeghyan propose a variant of YMP, the two-party multiple comparison (TPMC) protocol, that determines the greatest one over multiple (more than two) encrypted data between two parties. However, in Kaghazgaran and Sadeghyan's TPMC (KS-TPMC) protocol, one of two parties may guess the original data with a probability. In this paper, we introduce a new TPMC protocol to enhance the security by reducing this guess probability, and meanwhile has the same computation cost compared with KS-TPMC protocol. Additionally, the proposed TPMC protocol is more effective on reducing the attack probability for the large number of encrypted data. Thus, our TPMC protocol is suitable for applications on multiple comparison over encrypted data.