Anamorphic Private Set Intersection

Private Set Intersection (PSI) enables two parties to compute the intersection of their datasets while preserving privacy. However, in dictator-controlled environments where encryption mechanisms are subject to coercive regulation, traditional PSI protocols become vulnerable to key disclosure requirements and enforced computation controls, which can undermine their security guarantees. We introduce Anamorphic Private Set Intersection (Ana-PSI), a novel PSI protocol that incorporates Anamorphic Encryption (AE) to achieve covert intersection computation under coercive conditions. By leveraging homomorphic anamorphic encryption and a modified Bloom filter representation, Ana-PSI enables the computation of a hidden intersection while presenting a dictator with an innocuous result. We formally define the security model of Ana-PSI, analyze its resistance against coercive adversaries, and demonstrate its correctness under both normal and anamorphic decryption modes. Our work extends the feasibility of PSI to high-surveillance environments, ensuring privacy-preserving computation despite external scrutiny.