Smart Card Technical Reference

The Smart Card Technical Reference describes the Windows smart card infrastructure for physical smart cards and how smart card-related components work in Windows. This document also contains information about tools that information technology (IT) developers and administrators can use to troubleshoot, debug, and deploy smart card-based strong authentication in the enterprise.


This document explains how the Windows smart card infrastructure works. To understand this information, you should have basic knowledge of public key infrastructure (PKI) and smart card concepts. This document is intended for:

  • Enterprise IT developers, managers, and staff who are planning to deploy or are using smart cards in their organization.
  • Smart card vendors who write smart card minidrivers or credential providers.

What are smart cards?

Smart cards are tamper-resistant portable storage devices that can enhance the security of tasks such as authenticating clients, signing code, securing e-mail, and signing in with a Windows domain account.

Smart cards provide:

  • Tamper-resistant storage for protecting private keys and other forms of personal information
  • Isolation of security-critical computations that involve authentication, digital signatures, and key exchange from other parts of the computer. These computations are performed on the smart card
  • Portability of credentials and other private information between computers at work, home, or on the road

Smart cards can be used to sign in to domain accounts only, not local accounts. When you use a password to sign in interactively to a domain account, Windows uses the Kerberos version 5 (v5) protocol for authentication. If you use a smart card, the operating system uses Kerberos v5 authentication with X.509 v3 certificates.

Virtual smart cards were introduced to alleviate the need for a physical smart card, the smart card reader, and the associated administration of that hardware.


Windows Hello for Business and FIDO2 security keys are modern, two-factor authentication methods for Windows. Customers using virtual smart cards are encouraged to move to Windows Hello for Business or FIDO2. For new Windows installations, we recommend Windows Hello for Business or FIDO2 security keys.

In this technical reference

This reference contains the following topics: