Crypto Reading Group - Mohammad Hajiabadi-Challenges in Realizing CCA in Advanced Encryption Schemes

Abstract:CCA security is a fundamental notion in cryptography. There are standard techniques to generically achieve CCA security for all-or-nothing type public-key encryption schemes, such as heuristic approaches based on Fujisaki–Okamoto, or constructions in the standard model using tools like hinting PRGs. However, in more advanced settings, such as functional encryption or threshold encryption, these generic approaches break down. Moreover, defining CCA security in these settings is itself non-trivial and leads to subtle definitional challenges.