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...
Saved in:
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Ruhr-Universität Bochum
2025-03-01
|
| Series: | IACR Transactions on Symmetric Cryptology |
| Subjects: | |
| Online Access: | https://tosc.iacr.org/index.php/ToSC/article/view/12077 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | 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.
|
|---|---|
| ISSN: | 2519-173X |