Abstract
This paper constructs a new anonymous IBE scheme,and expands it to an anonymous HIBE scheme secure against full adaptive-ID attacks.These systems are built in composite order groups,which have four prime order subgroups.To achieve the anonymity,the authors blinded the public parameters and ciphertexts using the random elements of same subgroup.Moreover,the authors used the random elements of different subgroup to construct secret key for properly decryption.This idea is inspired by the related work,which proposed by Seo et al.in PKC 2009.To obtain full security,the authors applied the new techniques for dual system encryption recently introduced by Lewko and Waters in TCC 2010.Like the techniques used in their paper,the authors also used the semi-functional structures,and employed a hyhrid argument in the security by a sequence of games proof.And employed an additional dummy semi-functional structure to overcome the difficulty in the proof of the anonymity.The new anonymous HIBE scheme has short ciphertexts,and can be proven to be secure in the full-ID model using static assumptions.However,the previous schemes were only proven in the selective-ID model,under some non-static assumption which depended on the depth of the hierarchy.
Published Version
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