Narrow Bandwidth Is Not Inherent in Reverse Public-Key Encryption

International audienceReverse Public-Key Encryption (RPKE) is a mode of operation exploiting a weak form of key privacy to provide message privacy. In principle, RPKE offers a fallback mode, if the underlying encryption scheme’s message secrecy fails while a weak form of key privacy survives. To date, all published RPKE constructions suffer from a low bandwidth, and low bandwidth seems naturally inherent to reverse encryption. We show how reverse encryption can, in connection with and as a novel application of anonymous broadcast encryption, achieve high-bandwidth. We point out that by using traditional and reverse encryption simultaneously, a form of crypto-steganographic channel inside a cryptosystem can be provided