The secure authentication mechanism most widely deployed and used by
Internet application protocols is the transmission of clear-text
passwords over a channel protected by Transport Layer Security (TLS).
There are some significant security concerns with that mechanism,
which could be addressed by the use of a challenge response
authentication mechanism protected by TLS. Unfortunately, the HTTP
Digest challenge response mechanism presently on the standards track
failed widespread deployment, and have had success only in limited
This specification describes a family of HTTP authentication
mechanisms called the Salted Challenge Response Authentication
Mechanism (SCRAM), which addresses the security concerns and meets
the deployability requirements. When used in combination with TLS or
an equivalent security layer, a mechanism from this family could
improve the status-quo for application protocol authentication.