Test infrastructures are widely deployed in modern Systems-on-Chip (SoC). They allow the tester to control and observe the internal state of the SoC. However, a malicious user can exploit these infrastructures in order to extract secret information stored inside the SoC. In this paper, we review and compare security countermeasures based on the encryption of test data. The present techniques ensure the confidentiality of the exchanged messages between the circuit and the tester. Moreover, they provide lightweight user authentication in order to prevent malicious users from accessing the test infrastructure.