SMART App Launch
2.2.0 - STU 2.2 International flag

This page is part of the Smart App Launch Implementation Guide (v2.2.0: STU 2.2) based on FHIR (HL7® FHIR® Standard) R4. This is the current published version. For a full list of available versions, see the Directory of published versions

Client Authentication: Symmetric (shared secret)

Profile Audience and Scope

This profile describes SMART’s client-confidential-symmetric authentication mechanism. It is intended for SMART App Launch clients that can maintain a secret but cannot manage asymmetric keypairs. For clients that can manage asymmetric keypairs, Asymmetric Authentication is preferred. This profile is not intended for SMART Backend Services clients.

Authentication using a client_secret

If a client has registered for Client Password authentication (i.e., it possesses a client_secret that is also known to the EHR), the client authenticates by supplying an Authorization header with HTTP Basic authentication, where the username is the app’s client_id and the password is the app’s client_secret.


If the client_id is “my-app” and the client_secret is “my-app-secret-123”, then the header uses the value B64Encode(“my-app:my-app-secret-123”), which converts to bXktYXBwOm15LWFwcC1zZWNyZXQtMTIz. This gives the app the Authorization token for “Basic Auth”.

GET header:

Authorization: Basic bXktYXBwOm15LWFwcC1zZWNyZXQtMTIz