privacy-focused app developers

Abstract: This paper introduces TUTTI, a new CKKS bootstrapping procedure that outperforms previous low-latency solutions in multi-threaded latency for any number of messages and, most notably, has a lower latency than TFHE when bootstrapping a single one. Our bootstrapping builds upon SPRU (CK, TCHES 2027), improving it with new methods for exploiting parallelism and increasing the number of messages, as well as with a refined security analysis, of independent interest, of the block-binary secret keys of LMSS (AsiaCCS 2023). TUTTI bootstraps 4096 real-number messages in 46 to 83.4 ms on 192 threads to restore 1 to 9 multiplicative levels, outperforming SHIP (CHKS, Eurocrypt 2025) by a factor of up to 3 on the same machine. Unlike SHIP, TUTTI gains immediately from bootstrapping fewer messages, with a 256-message bootstrapping taking just 15 to 34 ms on 32 threads. For a single message, TUTTI takes 4.6 ms on 32 threads, whereas TFHE-rs needs 7.3 ms for a 4-bit bootstrapping on the same machine and thread count. We show that this advantage persists across different architectures: on an Apple M5 Pro laptop (ARM), TUTTI takes 2.4 ms on 14 threads, against 4.5 ms for TFHE-rs. Differences between CKKS and lightweight schemes such as TFHE remain on several fronts, from functionality to key sizes and security assumptions, but our work shows that multi-threaded latency is no longer one of them, closing a long-standing gap in the practical FHE literature.

Abstract: Romantic relationships shape physical, mental, and social well-being, and relationship quality is built through everyday interactions. Addressing minor issues early and reinforcing positive interactions help maintain relationship quality, and ubiquitous computing creates new opportunities to sense and support couples' relationships in daily life. However, existing systems remain largely developed with limited involvement from couples, raising questions about which types of sensing and support couples may accept in their private lives. To address this gap, we conducted exploratory needs-assessment interviews and co-design sessions with five co-located couples (10 participants) to identify their needs and preferences for relationship-attunement-enhancing technologies, including the use of LLMs. Couples' own designs converged on systems that detect meaningful moments---such as conflict onset---and offer subtle mediation rather than AI-generated advice, highlighting dyadic concerns around partners' agency, authenticity, and control over shared interaction data. We offer preliminary design implications for ubiquitous sensing and intervention systems that center the couple as a unit rather than the individual.