http://www.rfc-editor.org/rfc/rfc4785.txt
RFC 4785: Pre-Shared Key (PSK) Ciphersuites with NULL Encryption for Transport Layer Security (TLS), U. Blumenthal, P. Goel2007-01-01T23:00:00-00:00This document specifies authentication-only ciphersuites (with no encryption) for the Pre-Shared Key (PSK) based Transport Layer Security (TLS) protocol. These ciphersuites are useful when authentication and integrity protection is desired, but confidentiality is not needed or not permitted. [STANDARDS-TRACK]