Papers by Keyword: Pairing

Abstract: The concept of proxy re-encryption (PRE) was first introduced by Blaze et al. Since then several CCA secure PRE schemes have been presented. Weng et al. proposed a non-transitive bidirectional PRE scheme without pairings and proved that their scheme to be PRE-CCA secure in the random oracle model under the CDH assumption. However, we show that Weng et als non-transitive scheme is still transitive under the formal definition of non-transitivity presented in this paper. Moreover, the transitivity of Weng et al.s scheme also implies that it is not PRE-CCA secure.