Research On Revocable Generalized Identity-based Cryptography Algorithms

With the rapid development of Internet technology and prevalent of cloud computing, more and more sensitive data is being exchanged over the Internet and being stored in the cloud server. Though the Internet can make our life too much abundant and convenient, it has many security problems at the same time, which puts forward higher requirements to the Internet security. As more cryptosystems are applied to various scenes that are associated with the users’ interests, it is inevitable that the user key will be lost, expired or attribute changed. Therefore, in public key cryptography, especially identity-based cryptography and attribute-based cryptography, it is of great significance to research on how to revoke user and attribute timely and effectively. This paper focuses on the revocable technology in identity-based signcryption scheme(IBSC) and attribute-based encryption scheme(ABE). The main contributions of this paper are in the following:1. The paper studies the existing IBSC and summarizes the existing problems of revoking users, and then proposes a new revocable IBSC scheme. The new scheme not only can realize the user revocation and key update, but also can verify the ciphertext without accessing plaintext by any third party. In the standard model, the scheme is proven to be IND-CCA2 and EUF-CMA under DBDH assumption and CDH assumption, respectively, and the scheme safety is guaranteed in practical application.2. The paper studies the existing ABE and summarizes the existing problems, especially revoke user or attribute timely and efficient. We propose a new timely and efficient revocable ABE scheme, which supports the user and attribute revocation. In the new scheme, we achieve fine-grained access control. Not only can the scheme realize revocation on the user level, but also revoke on the attribute level. In addition, through rigorous proof, we show that our proposed scheme is secure under the DPBDHE assumption in the standard model. The scheme also is confidentiality, collusion resistance, forward and backward security.