The individual, group, or organization responsible for conducting a security control assessment.
Sources:
NIST SP 800-137 under Security Control Assessor
NIST SP 800-30 Rev. 1 under Security Control Assessor
NIST SP 800-39 under Security Control Assessor

  An attack enabled by leakage of information from a physical cryptosystem. Characteristics that could be exploited in a side-channel attack include timing, power consumption, and electromagnetic and acoustic emissions.
Sources:
NIST SP 800-63-3 under Side-Channel Attack

  Confidence that the supply chain will produce and deliver elements, processes, and information that function as expected.
Sources:
NISTIR 7622 under Supply Chain Assurance from DoD Key Practices and Implementation Guide - Adapted