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The primitive of verifiable database (VDB) enables the integrity of database when a resource-limited client outsources a huge dynamic database on an untrusted cloud server. Meanwhile, the client could perform various types of queries on the database such as index-based queries and keyword-based queries. In the real-world applications, it is more suitable to consider VDB schemes supporting full updating operations (i.e., replacement, insertion, and deletion). Inherently, forward/backward-secure searchable encryption schemes should be adopted to incorporate VDB schemes. In this paper, we first attempt to address the problem of how to perform forward-secure keyword searching on VDB schemes. Moreover, we present a concrete VDB construction that can support forward-secure keyword search and full updating operations. Security and efficiency analysis demonstrate that the proposed VDB schemes can achieve the desired security properties with high efficiency.

Many authenticated key agreement protocols based on identity information were published in recent years. Hsieh et al. presented their protocol in 2002. However, Tseng et al. found a flaw in the protocol which resulted in a key compromise impersonation attack. Later, Tseng proposed his protocol conforming which conforms to all desirable security properties and is efficient. In this paper we propose two new two-party identity-based authenticated key agreement protocols. The first is based on Hsieh et al.'s protocol and makes it immune against Tseng et al.'s attack, while the second is an efficiently improved protocol based on Tseng's protocol.