The application must ensure encrypted assertions, or equivalent confidentiality protections are used when assertion data is passed through an intermediary, and confidentiality of the assertion data is required when passing through the intermediary.

SAML is a standard for exchanging authentication and authorization data between security domains. SAML uses security tokens containing assertions to pass information about a principal (usually an end user) between a SAML authority, (identity provider), and a SAML consumer, (service provider). SAML assertions are usually made about a subject, (user) represented by the <Subject> element.

The confidentially of the data in a message as the message is passed through an intermediary web service may be required to be restricted by the intermediary web service. The intermediary web service may leak or distribute the data contained in a message if not encrypted or protected.