This policy setting allows you to control whether elliptic curve cryptography (ECC) certificates on a smart card can be used to log on to a domain.If you enable this policy setting ECC certificates on a smart card can be used to log on to a domain.If you disable or do not configure this policy setting ECC certificates on a smart card cannot be used to log on to a domain. Note: This policy setting only affects a user's ability to log on to a domain. ECC certificates on a smart card that are used for other applications such as document signing are not affected by this policy setting. Note: If you use an ECDSA key to log on you must also have an associated ECDH key to permit logons when you are not connected to the network.