Observations on TETRA Encryption Algorithm TEA-3
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 contra...
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| Format: | Article |
| Language: | English |
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Ruhr-Universität Bochum
2025-03-01
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| Series: | IACR Transactions on Symmetric Cryptology |
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| Online Access: | https://tosc.iacr.org/index.php/ToSC/article/view/12077 |
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| author | Jens Alich Amund Askeland Subhadeep Banik Tim Beyne Anne Canteaut Patrick Felke Gregor Leander Willi Meier Lukas Stennes |
| author_facet | Jens Alich Amund Askeland Subhadeep Banik Tim Beyne Anne Canteaut Patrick Felke Gregor Leander Willi Meier Lukas Stennes |
| author_sort | Jens Alich |
| collection | DOAJ |
| description |
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.
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| format | Article |
| id | doaj-art-99feeb2819f24342a94ebed76f7f116c |
| institution | DOAJ |
| issn | 2519-173X |
| language | English |
| publishDate | 2025-03-01 |
| publisher | Ruhr-Universität Bochum |
| record_format | Article |
| series | IACR Transactions on Symmetric Cryptology |
| spelling | doaj-art-99feeb2819f24342a94ebed76f7f116c2025-08-20T02:59:57ZengRuhr-Universität BochumIACR Transactions on Symmetric Cryptology2519-173X2025-03-012025110.46586/tosc.v2025.i1.276-308Observations on TETRA Encryption Algorithm TEA-3Jens Alich0Amund Askeland1Subhadeep Banik2Tim Beyne3Anne Canteaut4Patrick Felke5Gregor Leander6Willi Meier7Lukas Stennes8Ruhr University Bochum, Bochum, GermanyUniversity of Bergen, Bergen, NorwayUniversita della Svizzera Italiana, Lugano, SwitzerlandCOSIC, KU Leuven, Leuven, BelgiumInria, Paris, FranceUniversity of Applied Sciences Emden/Leer, Emden, GermanyRuhr University Bochum, Bochum, GermanyUniversity of Applied Sciences and Arts Northwestern Switzerland, Windisch, SwitzerlandRuhr University Bochum, Bochum, Germany 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. https://tosc.iacr.org/index.php/ToSC/article/view/12077TETRATEA-3Stream cipherCryptanalysisETSI |
| spellingShingle | Jens Alich Amund Askeland Subhadeep Banik Tim Beyne Anne Canteaut Patrick Felke Gregor Leander Willi Meier Lukas Stennes Observations on TETRA Encryption Algorithm TEA-3 IACR Transactions on Symmetric Cryptology TETRA TEA-3 Stream cipher Cryptanalysis ETSI |
| title | Observations on TETRA Encryption Algorithm TEA-3 |
| title_full | Observations on TETRA Encryption Algorithm TEA-3 |
| title_fullStr | Observations on TETRA Encryption Algorithm TEA-3 |
| title_full_unstemmed | Observations on TETRA Encryption Algorithm TEA-3 |
| title_short | Observations on TETRA Encryption Algorithm TEA-3 |
| title_sort | observations on tetra encryption algorithm tea 3 |
| topic | TETRA TEA-3 Stream cipher Cryptanalysis ETSI |
| url | https://tosc.iacr.org/index.php/ToSC/article/view/12077 |
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