Résumé
IEEE test standards have been developed in order to sustain the deployment of complex test infrastructures inside modern Integrated Circuits (IC). Security is a primary issue in test infrastructures. For instance, confidentiality of sensitive data flowing through the test infrastructure must be ensured. User authentication is also crucial in order to avoid secret stealing and/or device corruption. In this paper, we propose a secure JTAG implementation, based on stream cipher encryption. This countermeasure provides data confidentiality and lightweight user authentication at the cost of a little area overhead on the whole IC.