Study On Theory And Applications Of Certificateless Public Key Cryptosystem

Certificateless Public Key Cryptosystem (CLPKC) has been received a great dealof attention as its advantageous to both the traditional Public Key Cryptosystem (PKC)in the abolishment of the public key certificate and the Identity-based Cryptosystem(IBC) in avoiding key escrow. The research on CLPKC has importance in both theoryand application.This dissertation investigates the Certificateless crytosystem in both theory andapplications. We first study Certificateless signature and authenticated key agreementprotocol. Then, based on those theoretical results, we study Certificateless cryptosystemprotocols in different application scenarios such as mobile IP and wireless sensornetworks.The author obtains results as follows:1. An efficient pairing-free Certificateless authenticated key agreement (CLAKA)protocol is proposed based on additive elliptic-curve-group, which utilizes thecomputational Diffie-Hellman problem and realizes the implicit certificatelessauthentication. Moreover, our protocol minimizes the message exchange roundtime. The security of the proposed protocol can be proved in the random oraclemodel and the proposal achieves strong security. Also, the proposal eliminatesthe pairing operations, which makes it the most efficient CLAKAprotocols everknown.2. Based on the elliptic curve cryptosystem, a certificateless signature algorithm ispresented, without pairing operations and with reduced signature size, theproposed scheme is efficient. Therefore, the signature algorithm is suitable formobile environments with real-time requirements and limited computing power.3. A secure and efficient mobile IP registration protocol in certificateless publickey infrastructure is proposed. The protocol reduces the registration delaythrough a minimal usage of an efficient certificateless signature scheme for theauthentications between the foreign agent (FA) and the home agent (HA). Theprotocol excludes certificates, and can avoid the inborn problem of key escrowin ID-PKC. Because there are not pairing algorithms in the certificatelesssignature, the presented mobile IP registration scheme is both secure andefficient. 4. CLBAS, a certificateless multi-user broadcast authentication in wireless sensornetwork is put forward. The protocol employs a newly proposed pairing-freecertificateless signature with reduced signature size and the Schnorr signaturewith partial message recovery, and provides strong security, sound scalabilityand efficiency for the multi-user broadcast authentication in WSN.