Security Weaknesses of an "Anonymous Attribute Based Encryption" appeared in ASIACCS'13

Attribute-based Encryption (ABE) has found enormous application in fine-grained access control of shared data, particularly in public cloud. In 2013, Zhang et al proposed a scheme called match-then-decrypt [1], where before running the decryption algorithm the user requires to perform a match operation with attribute(s) that provides the required information to identify whether a particular user is the intended recipient for the ciphertext. As in [1], the match-then-decrypt operation saves the computational cost at the receiver and the scheme supports receivers’ anonymity. In this paper, we show that Zhang et al ’s scheme [1] does not support receivers’ anonymity. Any legitimate user or an adversary can successfully check whether an attribute is required in the matching phase, in turn, can reveal the receivers’ identity from the attribute.