Request-Based Comparable Encryption Scheme with Multiple Users

Order Preserving Encryption (OPE) is widely used for data searching. But, when all the numbers in the domain are encrypted by using OPE, an attacker can easily obtain the correspondence between encrypted numbers and original numbers. Furukawa proposed a new encryption scheme, which is called request-based comparable encryption, to solve the problem. However, comparable encryption only applies to single user. In this paper, a novel of request-based comparable encryption with multiple users is proposed. The different ciphertexts which are encrypted with different private keys can be compared by using the token transformation skill.