{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,1]],"date-time":"2025-10-01T15:30:41Z","timestamp":1759332641686,"version":"3.38.0"},"reference-count":0,"publisher":"Universitatsbibliothek der Ruhr-Universitat Bochum","issue":"1","license":[{"start":{"date-parts":[[2025,3,7]],"date-time":"2025-03-07T00:00:00Z","timestamp":1741305600000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["ToSC"],"abstract":"<jats:p>We present a number of observations on TEA-3, a stream cipher used in TETRA radio networks that was kept secret until recently. While the same also holds for the six other TETRA encryption algorithms, we pick TEA-3 to start with, as (i) it is not obviously weakened as TEA-{1,4,7} but (ii) in contrast to TEA-2 it is approved for extra-European emergency service, and (iii) as already noted by [MBW23] the TEA-3 design surprisingly contains a non-bijective S-box. Most importantly, we show that the 80-bit non-linear feedback shift register operating on the key decomposes into a cascade of two 40-bit registers. Although this hints at an intentional weakness at first glance, we are not able to lift our results to a practical attack. Other than that, we show how the balanced non-linear feedback functions used in the state register of TEA-3 can be constructed.<\/jats:p>","DOI":"10.46586\/tosc.v2025.i1.276-308","type":"journal-article","created":{"date-parts":[[2025,3,7]],"date-time":"2025-03-07T14:18:44Z","timestamp":1741357124000},"page":"276-308","source":"Crossref","is-referenced-by-count":1,"title":["Observations on TETRA Encryption Algorithm TEA-3"],"prefix":"10.46586","volume":"2025","author":[{"given":"Jens","family":"Alich","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Amund","family":"Askeland","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Subhadeep","family":"Banik","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tim","family":"Beyne","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anne","family":"Canteaut","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Patrick","family":"Felke","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gregor","family":"Leander","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Willi","family":"Meier","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lukas","family":"Stennes","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"25480","published-online":{"date-parts":[[2025,3,7]]},"container-title":["IACR Transactions on Symmetric Cryptology"],"original-title":[],"link":[{"URL":"https:\/\/tosc.iacr.org\/index.php\/ToSC\/article\/download\/12077\/11918","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/tosc.iacr.org\/index.php\/ToSC\/article\/download\/12077\/11918","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,3,7]],"date-time":"2025-03-07T14:18:44Z","timestamp":1741357124000},"score":1,"resource":{"primary":{"URL":"https:\/\/tosc.iacr.org\/index.php\/ToSC\/article\/view\/12077"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,3,7]]},"references-count":0,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2025,3,7]]}},"URL":"https:\/\/doi.org\/10.46586\/tosc.v2025.i1.276-308","relation":{},"ISSN":["2519-173X"],"issn-type":[{"value":"2519-173X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,3,7]]}}}