You can use smart card authentication to log in to the ESXi Direct Console User Interface (DCUI) by using a Personal Identity Verification (PIV), Common Access Card (CAC) or SC650 smart card instead of the default prompt for a user name and password.
A smart card is a small plastic card with an embedded integrated circuit chip. Many government agencies and large enterprises use smart card based two-factor authentication to increase the security of their systems and comply with security regulations.
When smart card authentication is enabled on an ESXi host, the DCUI prompts you for a valid smart card and PIN combination instead of the default prompt for a user name and password.
When you insert the smart card into the smart card reader, the ESXi host reads the credentials on it.
The ESXi DCUI displays your login ID, and prompts you for your PIN.
After you enter your PIN, the ESXi host matches it with the PIN stored on the smart card and verifies the certificate on the smart card with Active Directory.
After a successful verification of the smart card certificate, ESXi logs you in to the DCUI.
You can switch to user name and password authentication from the DCUI by pressing F3.
The chip on the smart card locks after a few consecutive incorrect PIN entries, usually three. If a smart card is locked, only selected personnel can unlock it.