The authentication flow is the definition of how the tokens to identify users are exchanged. Picturepark external Identity Provider must support Authorization Code Flow with PKCE. PKCE, pronounced “pixy” is an acronym for Proof Key for Code Exchange, which does not require users to provide a client_secret. The standard Authorization Code flow would require this. The main benefit is the reduced risk for native apps, as there are no embedded secrets in the source code and this in return limits exposure to reverse engineering.