Fair Cryptosystem - Key Escrew

This is when you split the key among 2 or more parties in order for them to keep the portions of the key in escrow so that, under certain circumstances, an authorized third party may gain access to those keys. For further details ref to https://en.wikipedia.org/wiki/Key_escrow

NIST 800-53A

NIST 800-53A is a special publication which provides a set of procedures for conducting assessments of security controls and privacy controls employed within federal information systems and organizations.

This can be a topic of CISSP questions. So it is important to remember this special publication and its intent.