TETRA Radio Code Encryption Has a Flaw: A Backdoor (www.wired.com)
from tedu to cryptography on 25 Jul 2023 17:32
https://azorius.net/p/lWS3r4w3vzg2v72KHt

For more than 25 years, a technology used for critical data and voice radio communications around the world has been shrouded in secrecy to prevent anyone from closely scrutinizing its security properties for vulnerabilities. But now it’s finally getting a public airing thanks to a small group of researchers in the Netherlands who got their hands on its viscera and found serious flaws, including a deliberate backdoor.

To obtain the algorithms, the researchers purchased an off-the-shelf Motorola MTM5400 radio and spent four months locating and extracting the algorithms from the secure enclave in the radio’s firmware. They had to use a number of zero-day exploits to defeat Motorola protections, which they reported to Motorola to fix. Once they reverse-engineered the algorithms, the first vulnerability they found was the backdoor in TEA1.

All four TETRA encryption algorithms use 80-bit keys, which, even more than two decades after their release, still provides sufficient security to prevent someone from cracking them, the researchers say. But TEA1 has a feature that reduces its key to just 32 bits—less than half the key’s length. The researchers were able to crack it in less than a minute using a standard laptop and just four ciphertexts.

#cryptography