This is a potential security issue, you are being redirected to https://csrc.nist.gov.
Highly reliable hardware, firmware, and software components that perform specific, critical security functions. Because roots of trust are inherently trusted, they must be secure by design. Roots of trust provide a firm foundation from which to build security and trust.
NIST SP 800-172 from NIST Roots of Trust Project
A starting point that is implicitly trusted.
NISTIR 8320 under Root of Trust