Cryptology ePrint Archive: Report 2014/937

Analysis of Lewko-Sahai-Waters Revocation System

Zhengjun Cao and Lihua Liu

Abstract: In 2010, Lewko, Sahai and Waters proposed an efficient revocation system but they neglected the security differences between one-to-one encryption and one-to-many encryption. In their system, an authority generates all users' decryption keys once and for all. We remark that the inherent drawback results in that the system is vulnerable to an attack launched by some malicious users. These malicious users could exchange their decryption keys after they receive them from the authority in order to maximize their own interests. Thus, the Lewko-Sahai-Waters revocation system cannot truly revoke a malicious user. From the practical point of view, the flaw discounts greatly the importance of the system.

Category / Keywords: cryptographic protocols / Broadcast encryption, revocation system,one-to-one encryption, one-to-many encryption

Date: received 14 Nov 2014

Contact author: liulh at shmtu edu cn

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Version: 20141118:190247 (All versions of this report)

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