  The emergence of distributed manufacturing ecosystems for electronic hardware
involving untrusted parties has given rise to diverse trust issues. In
particular, IP piracy, overproduction, and hardware Trojan attacks pose
significant threats to digital design manufacturers. Watermarking has been one
of the solutions employed by the semiconductor industry to overcome many of the
trust issues. However, current watermarking techniques have low coverage, incur
hardware overheads, and are vulnerable to removal or tampering attacks.
Additionally, these watermarks cannot detect Trojan implantation attacks where
an adversary alters a design for malicious purposes. We address these issues in
our framework called SIGNED: Secure Lightweight Watermarking Scheme for Digital
Designs.
  SIGNED relies on a challenge-response protocol based interrogation scheme for
generating the watermark. SIGNED identifies sensitive regions in the target
netlist and samples them to form a compact signature that is representative of
the functional and structural characteristics of a design. We show that this
signature can be used to simultaneously verify, in a robust manner, the
provenance of a design, as well as any malicious alterations to it at any stage
during design process. We evaluate SIGNED on the ISCAS85 and ITC benchmark
circuits and obtain a detection accuracy of 87.61\% even for modifications as
low as 5-gates. We further demonstrate that SIGNED can benefit from integration
with a logic locking solution, where it can achieve increased protection
against removal/tempering attacks and incurs lower overhead through judicious
reuse of the locking logic for watermark creation.
