id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-139715-jyfmnnf5	Holzapfel, Kilian	Digital Contact Tracing Service: An improved decentralized design for privacy and effectiveness	2020-06-29		.txt	text/plain	12267	796	61	We present a secure solution for a digital contact tracing service (DCTS) that protects the users' privacy, identity and personal data from attackers. In order to check whether the user has been in contact with an infected person, they download all unchecked TCNs stored on the server and check for matches within their own list of observed TCNs. When encountering matches, the app can perform a risk assessment based on exposure time period and proximity. In order to avoid this attack, we can check for the number of TCNs that are both in our set of encountered TCNs and in the set of infected TCNs. An algorithm determining the private set intersection cardinality with low communication cost (see for example 3 ) is a valuable strategy in order to discover the exposure to infectious contacts without risking the identification of the patient (details are described in Section 3.6).	./cache/cord-139715-jyfmnnf5.txt	./txt/cord-139715-jyfmnnf5.txt