Subtleties in Security Definitions for Predicate Encryption with Public Index.

摘要: We take a critical look at established security definitions for predicate encryption (PE) with public index under chosen-plaintext attack (CPA) and chosen-ciphertext (CCA). identify three different formalizations of key handling in the literature, implicitly assumed to lead same notion. Contrary this assumption, we prove that corresponding models result two notions CPA CCA. Similarly recent results PKE conventional key-encapsulation mechanism (KEM), analyze subtleties PE (P-KEM) regarding so-called “no-challenge-decryption” condition. While are similar, P-KEM significantly differ from KEM. As consequence our work, suggest scenarios.