When a user or administrator inserts a smart card into a smart card reader, the user certificates on the smart card are copied to the local certificate store on the client system if the client operating system is Windows. The certificates in the local certificate store are available to all of the applications running on the client computer, including Horizon Client.

When a user or administrator initiates a connection to a Connection Server instance that is configured for smart card authentication, the Connection Server instance sends a list of trusted certificate authorities (CAs) to the client system. The client system checks the list of trusted CAs against the available user certificates, selects a suitable certificate, and then prompts the user or administrator to enter a smart card PIN. If there are multiple valid user certificates, the client system prompts the user or administrator to select a certificate.

The client system sends the user certificate to the Connection Server instance, which verifies the certificate by checking the certificate trust and validity period. Typically, users and administrators can successfully authenticate if their user certificate is signed and valid. If certificate revocation checking is configured, users or administrators who have revoked user certificates are prevented from authenticating.

In some environments, a user's smart card certificate can map to multiple Active Directory domain user accounts. A user might have multiple accounts with administrator privileges and needs to specify which account to use in the Username hint field during smart card login. To make the Username hint field appear on the Horizon Client login dialog box, the administrator must enable the smart card user name hints feature for the Connection Server instance in Horizon Console. The smart card user can then enter a user name or UPN in the Username hint field during smart card login.

If your environment uses a Unified Access Gateway appliance for secure external access, you must configure the Unified Access Gateway appliance to support the smart card user name hints feature. The smart card user name hints feature is supported only with Unified Access Gateway version 2.7.2 and later. For information about enabling the smart card user name hints feature in a Unified Access Gateway appliance, see the Deploying and Configuring VMware Unified Access Gateway document.

Display protocol switching is not supported with smart card authentication in Horizon Client. To change display protocols after authenticating with a smart card in Horizon Client, a user must log off and log on again.