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ETSI
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TEA4
TETRA Encryption Algorithm 4

TEA4, short for TETRA Encryption Algorithm 4, 1 is a stream cipher associated with Terrestrial Trunked Radio (TETRA), a European standard for public and emergency services, standardized by the European Telecommunications Standards Institute (ETSI). Like the TEA1 algorithm it is intended for commercial use and restricted export. Although the structure of the cipher is still unknown, it is likely that it has weaknesses similar to TEA1 by design.

In July 2023, Dutch cyber security firm Midnight Blue revealed that it had managed to extract, isolate and analyse the TEA1, TEA2 and TEA3 algorithms from a working TETRA radio as part of its TETRA:BURST research project. Unfortunately, no TEA4 firmware was available at the time, although other vulnerabilities in the TETRA protocol suite were identified [2][4].

  1. Not to be confused with Tiny Encryption Algorithm.  Wikipedia

Source code
As part of the TETRA:BURST project, Midnight Blue researchers managed to extract and reverse-engineer the firmware from an operational TETRA radio, and construct an equivalent of the code in the C programming language. This source code is now available to researchers [II]. Note that the source code of TEA4 is not included as its firmware was not available to the researchers.

 Download the full source code


Publications
  1. Carlo Meijer, Wouter Bokslag and Jos Wetzels,
    All cops are broadcasting: TETRA under scrutiny

    Paper submitted to Crypto Museum. 9 August 2023.

  2. Full source code of TAA1, TEA1, TEA2 and TEA3 algorithms in C
    Reverse-engineered and used for analysis and real life tests.
    Midnight Blue, 9 August 2023.

  3. All Cops Are Broadcasting, Breaking TETRA after decades in the shadows
    Presentation by Jos Wetzels, Carlo Meijer and Wouter Bokslag at Black Hat 2023.
    Midnight Blue, 9 August 2023
References
  1. Wikipedia, Terrestrial Trunked Radio
    Visited 27 July 2023.

  2. TETRA:BURST
    Midnight Blue, 24 July 2023.
     More

  3. Cees Jansen, TEA co-developer at Philips Crypto BV
    Personal correspondence. Crypto Museum, July 2023.

  4. Carlo Meijer, Wouter Bokslag and Jos Wetzels,
    All cops are broadcasting: TETRA under scrutiny

    Paper submitted to Crypto Museum. 9 August 2023.
Further information
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Crypto Museum. Created: Wednesday 09 August 2023. Last changed: Saturday, 12 August 2023 - 14:04 CET.
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