SSSN: Secured Streaming Scan Network

Abstract

During last decade, IEEE standard 1687 or IJTAG has been utilized to test the embedded instruments on chips that support test and measurement applications. Recently, IJTAG has been incorporated into the newly developed testing architecture referred as a Streaming Scan Network (SSN) for efficient testing of the complex System-on-Chips (SoCs). IJTAG registers are used to configure the components of a Streaming Scan Host (SSH) node associated with each core in the SSN network. SSN supports packetized test data distribution for streaming of the test data through SSN bus. SSN provides efficient SoC testing by several times reduction in test time and test data volume with limited pin count. Although SSN outshines in providing testing benefits, it lacks security support. An unauthorized user can maliciously modify the configuration registers and extracts sensitive information. Presence of untrusted modules in the network also amplifies the security concerns as each packet may contain test data of multiple cores. Hence, an untrusted cores can simply sniff the data destined for other cores. Therefore, to address the security issues in SSN test architecture, one needs to protect the system against internal untrusted third-party intellectual property (3PIP) modules and unauthorized users. This work discusses the security vulnerabilities of SSN architecture by demonstrating an attack scenario. Keeping the flexibility of SSN intact, we propose a modified SSH architecture and an authorization unit to ensure security against data sniffing attacks and unauthorized accesses, respectively. A state-of-the-art scheme is compared against the proposed approach in terms of area overheads. Thus, this paper presents a multi-level methodology with very low area and testing overheads for secure SSN.