A web server must maintain the confidentiality of controlled information during transmission through the use of an approved TLS version.

Transport Layer Security (TLS) is a required transmission protocol for a web server hosting controlled information. The use of TLS provides confidentiality of data in transit between the web server and client. FIPS 140-2 approved TLS versions must be enabled and non-FIPS-approved SSL versions must be disabled. NIST SP 800-52 defines the approved TLS versions for government applications.