Mode of Operation for Modification, Insertion, and Deletion of Encrypted Data

Due to the development of 5G communication, many aspects of information technology (IT) services are changing. With the development of communication technologies such as 5G, it has become possible to provide IT services that were difficult to provide in the past. One of the services made possible through this change is cloud-based collaboration. In order to support secure collaboration over cloud, encryption technology to securely manage dynamic data is essential. However, since the existing encryption technology is not suitable for encryption of dynamic data, a new technology that can provide encryption for dynamic data is required for secure cloud-based collaboration. In this paper, we propose a new encryption technology to support secure collaboration for dynamic data in the cloud. Specifically, we propose an encryption operation mode which can support data updates such as modification, addition, and deletion of encrypted data in an encrypted state. To support the dynamic update of encrypted data, we invent a new mode of operation technique named linked-block cipher (LBC). Basic idea of our work is to use an updatable random value so-called link to link two encrypted blocks. Due to the use of updatable random link values, we can modify, insert, and delete an encrypted data without decrypt it.