International Association for Cryptologic Research (IACR)
Abstract
Recently, Al-Riyami and Paterson proposed a generic conversion from
CL-PKE (Certificateless Public Key Encryption) to CBE (Certificate
Based Encryption) and claimed that the derived CBE scheme is secure
and even more efficient than the original scheme of Gentry. In this
paper, we show that their conversion is wrong due to the flaw of the
security proof. It leads the new concrete CBE scheme by Al-Riyami
and Paterson to be invalidated. In addition, our result supports the
impossibility to relate both notions in any directions
