Research On Several Algorithms In Identity-Based Cryptography

The challenge today in developing secure systems based on public key cryptography is not only choosing appropriately secure algorithms and implementing, but also developing an infrastructure to support the authenticity of a user's public key. In the traditional public key infrastructure (PKI), certificates are used to provide an assurance of the relationship between public keys and the identities that hold the corresponding private keys. However, PKI faces many challenges in practice, such as the scalability of the infrastructure and certificate management. To address the shortcomings of PKI, Shamir proposed the notion of identity-based cryptography (IBC) in 1985. In IBC, the public keys are derived from the users'identities, such as a username or an e-mail address. The certificate is not required to authenticate the public keys of users. IBC is another valid way to authenticate the user's public key. Compared with PKI, IBC has advantages in key management. Shamir proposed the first identity-based signature scheme when he introduced the notion of IBC. But the research on identity-based encryption has less progress. Until 2001, Boneh and Franklin proposed a practical and secure identity-based encryption using Weil pairing, which makes the IBC become a research hot point again. Since then, many identity-based cryptosystems have been proposed. However, IBC still has some open problems such as key escrow, key revocation, key evolving, security model and so on. It is important to research and solve these problems not only on theory but also on practice. This paper focuses on these problems, proposes some valid schemes and gets some research results. The main researches in the paper are as follows:1. Developing identity-based authentication protocols. An identity-based authentication protocol for Wireless local area network (WLAN) is proposed. And the hardware environment and process for protocol are described.2. Proposing an improved identity-based encryption (IIBE). This algorithm integrates traditional public key encryption and identity-based encryption. Compared with the former, it needn't certificates and certificates management. And compared with the latter, it solves the problems of key escrow and revocation. IIBE is constructed by bilinear pairing on elliptic cures and its security can be reduced to the computational Bilinear Diffie-Hellman assumption. IIBE has adaptively chosen ciphertext security in the random oracle model.3. Developing identity-based key evolving algorithms. On one hand, identity-based encryption with forward security (IBE-FS) is proposed. Any prior time period keys are still secure even if current time period key is exposed. In the random oracle model, IBE-FS is proved to be secure. Simulation results show that IBE-FS is efficient. On the other hand, identity-based encryption with intrusion resilient (IBE-IR) is presented. Key updating being implemented by base and user, IBE-IR achieves key forward and backward security. Furthermore, key forward security is achieved even though base is exposed. As compared with Dodis's scheme, IBE-IR can achieve the same key security, but the algorithm complexity is obviously reduced. Through simulation testing, it is shown that the proposed scheme is more efficient than Dodis's scheme.4. Developing identity-based cryptography in grid. First of all, without certificates, identity-based architecture for grid (IBAG) is proposed. Secondly, identity-based encryption (IBE) and identity-based signature (IBS) are presented. IBE is proved to be secure. IBE and IBS is analyzed in simulation testing. Thirdly, Based on IBAG, IBE and IBS, an identity-based authentication protocol (IBAP) is proposed. Through simulation testing, it is shown that the authentication protocol is more lightweight and efficient than SSL authentication protocol SAP, specially the more lightweight user side. This contributes to the larger grid scalability. In the end, an improved scheme is proposed with regard to grid security infrastructure (GSI). The scheme improves the three protocols of GSI. Through simulation experiment, it is shown that the improved scheme is more efficient than GSI.