YubiKey Personal Identity Verification (PIV) Attestation - with the TameMyCerts Policy Module for Microsoft Active Directory Certificate Services (ADCS)

Since the recently released version 1.7, the TameMyCerts Policy Module for Microsoft Active Directory Certificate Services supports Personal Identity Verification (PIV) attestation for YubiKeys.

A YubiKey is a compact security token that can be used, among other things, like a smart card for the secure storage and use of certificates and can therefore also be used for passwordless logon to Active Directory environments.

This cool function was developed by Oscar Virot and integrated into TameMyCerts. This makes it possible to provide cryptographic proof when issuing certificates and thus ensure that a key pair is actually generated with a YubiKey and secured by it and cannot be exported.

This can be particularly helpful in complying with the NIS2 directive if companies decide to use certificates as a second factor for logon with security-critical accounts in Active Directory.

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Configuring the Trusted Platform Module (TPM) Key Attestation

Since Windows 8, it is possible to protect the private keys of certificates with a Trusted Platform Module (TPM), if one is present . This makes the key non-exportable - even with tools like mimikatz.

However, it is not obvious at first glance that it cannot be guaranteed that a TPM is really used. It is true that no request via the Microsoft Management Console or autoenrollment is possible if the computer does not have a TPM.

However, the configuration in the certificate template is only a default setting for the client. When a certificate is requested, the certification authority will not explicitly check whether a Trusted Platform Module was really used .

To ensure that the private key of a certificate request has really been protected with a Trusted Platform Module, only the TPM Key Attestation remains.

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