Digital surveillance of suspects must be silent so as not to alert them. However, systems currently in use lack stringent technical mechanisms to ensure the legality of these measures. Researchers at the Karlsruhe Institute of Technology (KIT) and the University of Luxembourg have now designed a security protocol that enables, for example, judicially ordered surveillance of end-to-end encrypted or anonymous communications, but at the same time prevents or detects mass and unlawful surveillance. The team from KASTEL Security Research Labs at KIT presented initial results in a publication for the Asiacrypt 2023 conference. Read more