DCCA-Secure Public-Key Encryptions from Hybrid Paradigms

Detectable Chosen Cipher text Security (DCCA security) is a security notion for Public-Key Encryptions proposed recently in [1]. A DCCA-secure encryption is not necessarily CCA-secure, but dangerous decryption queries can be detected and are not allowed to be requested to the decryption oracle. DCCA-secure schemes may helps in constructing of CCA-secure ones. In this paper, we show there are already DCCA-secure public-key encryptions from popular KEM+DEM style hybrid paradigms, and passive security for DEM is sufficient for achieving DCCA-secure hybrid PKEs both for KEM+DEM and Tag-KEM/DEM paradigms. Furthermore, two DCCA-secure Public-Key schemes constructed from CCA secure KEMs by using hybrid paradigms are presented, which fall outside any of the three cases pointed out in [1].