CatNap: Leveraging Generic MPC for Actively Secure Privacy-enhancing Proximity Testing with a Napping Party Topics: Applied Cryptography; Privacy; Security and Privacy in Location-Based Services; Security and Privacy in Mobile Systems; Security and Privacy in Social Networks In Proceedings of the 19th International Conference on Security and Cryptography SECRYPT - Volume 1, 237-248, 2022 , Lisbon, Portugal