## Cryptology ePrint Archive: Report 2012/201

Comment an Anonymous Multi-receiver Identity-based Encryption Scheme

J.H.Zhang, Y.B.Cui

Abstract: Anonymous receiver encryption is an important cryptographic primitive. It can protect the privacy of the receiver. In 2010, Fan \emph{et al} proposed an anonymous multi-receiver ID-based encryption by using Lagrange interpolating polynomial. Recently, Wang \emph{et al} showed that Fan \emph{et al}'s scheme satisfied anonymity of the receivers. Then they provided an improved scheme to fix it and showed that the improved scheme was secure. Unfortunately, we pointed out that Wang \emph{et al}'s improved scheme did't satisfy the receiver's anonymity by analyzing the security of the scheme yet. After analyzing the reason to produce such flaw, we give an improved method to repair it and show that our improved scheme satisfies the receiver's anonymity, and the improved scheme has advantage over Wang \emph{et al}'s scheme in terms of computational cost.