Paper 2026/816

From Rerandtopia to Interceptopia, the Anamorphic Encryption Saga Rises

Abstract

Nowadays, governments are world-wide pushing towards building infrastructures to intercept, decrypt and prevent communications among citizens with the goal of catching criminals. The recent notion of anamorphic encryption proposed by Persiano et al. [Eurocrypt 2022] faces the risks of abuses derived from such infrastructures that could be maliciously leveraged to realize the phantom menace of large-scale mass-surveillance programs. Several recent papers showed positive results on the existence of anamorphic encryption schemes, mostly confined to basic settings. In this work we consider extreme scenarios where in addition to obtaining secret keys, the authority actively tries to sanitize ciphertexts removing covert communication. Despite anamorphic encryption might look impossible to achieve in the above settings, we give new definitions and somewhat surprising positive results in two scenarios: Rerandtopia and Interceptopia. Our main construction consists of two layers of encryption. Interestingly, when carefully instantiated, our scheme achieves a notion of re-randomizable CCA encryption that outperforms the state of the art in terms of assumptions and efficiency.