design choice

Active Directory Certificate Services (ADCS) now supports the generation of post-quantum certificates, enhancing quantum-safe cryptography within Windows' secure connection protocols. Microsoft has integrated PQ TLS hybrid key exchange into the Windows Transport Layer Security (TLS) stack, providing protection against "Harvest Now, Decrypt Later" attacks. The PQ TLS hybrid key exchange combines traditional cryptographic methods with the NIST ML-KEM algorithm, offering three hybrid combinations: X25519MLKEM768, SecP256r1MLKEM768, and SecP384r1_MLKEM1024. This feature is available in preview via the Windows Insider Program and will be rolled out to Windows 11 and Windows Server. Additionally, Windows cryptography APIs now support composite ML-KEM and ML-DSA algorithms, which are NIST-approved standards for key exchange and digital signatures, enhancing security by requiring multiple components to be compromised. Microsoft emphasizes the importance of establishing new Certification Authorities (CAs) for implementing post-quantum certificate issuance, as existing CAs cannot be upgraded. The introduction of ML-DSA support within ADCS allows organizations to counter HNDL risks associated with long-lived data. Organizations are encouraged to inventory their use of public-key cryptography, prioritize systems protecting sensitive data, and test hybrid and composite approaches in non-production environments to facilitate a smooth transition to quantum-safe cryptography.