A Universal Sequential Authentication Scheme for TAPC-Based Test Standards

Integrated circuits (ICs) have become extremely complex nowadays. Therefore, multiple test standards could be employed to handle different testing scenarios. Unfortunately, this also leads to serious security problems since attackers can exploit the excellent controllability and observability of test standards to steal confidential information or disrupt the circuit’s functionality. This article proposes a universal sequential authentication scheme that is compatible with test standards employing the test access port controller (TAPC) defined in IEEE Std 1149.1. The main objective is to protect multiple TAPC-based test standards with a universal security module. In this scheme, only authorized test data can be updated to the target register to control the corresponding test standard, and only the response to authorized test data can be output. The key idea is to generate different authentication keys for different test data, and even with the same set of test data, if their input sequences are different, their authentication keys will also be different. Furthermore, we develop an irreversible obfuscation mechanism to generate fake output data to confuse attackers. Due to its irreversibility, the original correct output data cannot be deduced from the fake output data. Experimental results on a typical processor, i.e., SCR1, show that the proposed scheme causes no time overhead, and the area overhead is only 1.74%.