De-anonymization attack in TETRA

TETRA's identity encryption method uses a weak 64-bit key that can be recovered from just three pairs of encrypted and unencrypted identities, allowing attackers to impersonate users or decrypt private communications.

The TA61 identity encryption function derives its key material from a single 64-bit SCK or CCK value, enabling key recovery through meet-in-the-middle attacks with minimal known plaintext-ciphertext pairs. An adversary with access to three encrypted/unencrypted identity pairs can reconstruct the encryption key and subsequently encrypt or decrypt arbitrary identities, compromising confidentiality and user anonymity in TETRA Class 2 and 3 networks.