Reflections on the security proofs of Boneh-Franklin identity-based encryption scheme  

作　　者：CHEN Yu CHEN LiQun LIN DongDai 

机构地区：[1]State Key Laboratory of Information Security (SKLOIS), Institute of Information Engineering, Chinese Academy of Sciences [2]Hewlett Packard Labs,Long Down Avenue, Stoke Gifford, Bristol, BS34 8QZ, UK

出　　处：《Science China Mathematics》2013年第7期1385-1401,共17页中国科学：数学（英文版）

基　　金：supported by National Natural Science Foundation of China(Grant No.60970152);IIE's Research Project on Cryptography(Grant No.Y3Z0011102);the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA06010701);National Key Basic Research Program of China(973 Program)(Grant No.2011CB302400)

摘　　要：In this paper, we first review the existing proofs of the Boneh-Franklin identity-based encryption scheme (BF-IBE for short), and show how to admit a new proof by slightly modifying the specifications of the hash functions of the original BF-IBE. Compared with prior proofs, our new proof provides a tighter security reduction and minimizes the use of random oracles, thus indicates BF-IBE has better provable security with our new choices of hash functions. The techniques developed in our proof can also be applied to improving security analysis of some other IBE schemes. As an independent technical contribution, we also give a rigorous proof of the Fujisaki-Okamoto (FO) transformation in the case of CPA-to-CCA, which demonstrates the efficiency of the FO-transformation (CPA-to-CCA), in terms of the tightness of security reduction, has long been underestimated. This result can remarkably benefit the security proofs of encryption schemes using the FO-transformation for CPA-to-CCA enhancement.In this paper, we first review the existing proofs of the Boneh-Franklin identity-based encryption scheme （BF-IBE for short）, and show how to admit a new proof by slightly modifying the specifications of the hash functions of the original BF-IBE. Compared with prior proofs, our new proof provides a tighter security reduction and minimizes the use of random oracles, thus indicates BF-IBE has better provable security with our new choices of hash functions. The techniques developed in our proof can also be applied to improving security analysis of some other IBE schemes. As an independent technical contribution, we also give a rigorous proof of the Fujisaki-Okamoto （FO） transformation in the case of CPA-to-CCA, which demonstrates the efficiency of the FO-transformation （CPA-to-CCA）, in terms of the tightness of security reduction, has long been underestimated. This result can remarkably benefit the security proofs of encryption schemes using the FO-transformation for CPA-to-CCA enhancement.

关 键 词：identity-based encryption Fujisaki-Okamoto transformation provable security cascading reduction 

分 类 号：TP309.7[自动化与计算机技术—计算机系统结构]