What item should an Architect consider when designing a Delegated Authentication implementation?

The web service that is used for delegated authentication should be secured with TLS using Salesforce trusted certificates4. This ensures that the communication between Salesforce and the external authentication method is encrypted and authenticated. The other options are not relevant for designing a delegated authentication implementation. The web service does not need to accept one to four inputmethod parameters, as it can accept any number ofparameters as long as they are wrapped in a SOAP envelope5. The web service does not need to use the Salesforce Federation ID to identify the user, as it can use any identifier that is unique and consistent across systems6. The web service does not need to implement acustom password decryption method, as it can use any encryption or hashing algorithm that is supported by both systems7. References: Delegated Authentication, Enable ‘Delegated Authentication’, Delegated Authentication Flow in Salesforce, FAQs for Delegated Authentication