Test Data Encryption with a New Stream Cipher

Additive stream ciphers (SCs) play a host of roles in securing variety of digital ecosystems. In particular, they can encrypt and decrypt test data used in manufacturing and in-system tests of digital integrated circuits (ICs). In this capacity, SCs have become an essential part of instruments that protect ICs against hardware security threats and mitigate risks associated with an unauthorized access and usage of ICs, possibly due to scan chains. However, many IC vendors keep raising concerns attributable to the complexity of existing SCs in terms of area overhead, performance, impact on a design flow, and testability. Here is where this work comes in. It introduces a simple and lightweight, yet effective and scalable, test data stream cipher Lancet developed for the Streaming Scan Network (SSN) technology to decrypt and encrypt the content of the IJTAG communication and the SSN bus. It builds on a hybrid ring generator working in tandem with two nonlinear Galois feedback shift registers to yield a large number of parallel, cryptographically secure pseudorandom keystreams. A comprehensive evaluation, including NIST test suits, show the efficiency of the proposed cipher, and is reported herein.