Cryptography that consists of: (i) an approved algorithm; (ii) an implementation that has been approved for the protection of classified information in a particular environment; and (iii) a supporting key management infrastructure.
Sources:
CNSSI 4009-2015
Cryptography that consists of an approved algorithm, an implementation that has been approved for the protection of classified information and/or controlled unclassified information in a specific environment, and a supporting key management infrastructure.
Sources:
NIST SP 800-171r3
from
NIST SP 800-53 Rev. 5
NIST SP 800-53 Rev. 5