Definition of Simple authentication and security layer

Simple Authentication and Security Layer (SASL) is a framework for authentication and data security in Internet protocols. It decouples authentication mechanisms from application protocols, in theory allowing any authentication mechanism supported by SASL to be used in any application protocol that uses SASL. Authentication mechanisms can also support proxy authorization, a facility allowing one user to assume the identity of another. Authentication mechanisms can also provide a data security layer offering data integrity and data confidentiality services. DIGEST-MD5 is an example of mechanisms which can provide a data security layer. Application protocols that support SASL typically also support Transport Layer Security (TLS) to complement the services offered by SASL.