标准模型下全安全的密钥策略属性基加密方案

A Fully Secure KP-ABE Scheme in the Standard Model

随着社交网络、云存储等新事物的出现,属性基加密以其强灵活性、强高效性、强安全性等优点得到了广泛的应用,但是目前的属性基加密方案大都是选择性安全的,不能很好地满足现实的应用需求,所以如何构造全安全的属性基加密方案成为密码学界研究的热点.针对以上问题,首先利用对偶系统加密构造了一个高效的密钥策略属性基加密方案;然后结合Lewko-Waters最新提出的证明思想证明了方案在标准模型下的全安全性;最后经分析比较,该方案的公私钥和密文长度与选择性安全的GPSW方案相当,但是安全性更高.同Lewko-Okamoto方案相比,该方案的安全性与之相同,但是具有较短的公钥长度和密文长度,方案的效率更高;而且,与Lekwo-Waters的密文策略的属性基加密方案相对应,该方案在全安全证明中应用了选择性安全模型中的证明方法,对进一步研究选择性安全模型与全安全模型之间的关系具有重要意义.

With the invention of many new applications such as social network and cloud storage, attribute-based encryption has been studied and applied widely because of its great flexibility, high efficiency and high security. As the current existing attributed-based encryption schemes are most selectively secure, which can＇t meet the need of the reality well, how to construct fully secure ABE has been the focus of cryptography. Aimed at the problems mentioned above, an key-policy ABE scheme is firstly constructed by using the dual encryption system in this paper, then the scheme is proved to fully secure in the standard model with the new ideas proposed by Lewko and Waters. Finally the comparison results show that the public and private key lengths of our scheme are similar to the selectively secure GPSW scheme, but our scheme is more secure. Compared with the Lewko- Waters scheme, our scheme has the same security, but has shorter public and private key lengths, which is more efficient. What＇s more, similar to the ciphertext-policy scheme of Lekwo-Waters, the techniques of selective security are also utilized in the security proof of our key-policy ABE, which is important in the research of the relation between the selective and full security models.