Is Windows Quantum Safe?
Not by default. Windows shipped post-quantum primitives (ML-KEM/ML-DSA) in SymCrypt/CNG (generally available November 2025), but SChannel TLS still uses RSA/ECDH key exchange unless PQC is explicitly enabled.
Key Takeaway: Windows is in transition to quantum safety. Deploy PQC-capable TLS termination in front of Windows services. Use QScout to assess current Windows TLS configuration.
- Modality
- Infrastructure
- Vulnerability
- SChannel TLS uses RSA/ECDH key exchange — vulnerable to Shor's algorithm.
- NIST status
- Microsoft shipped ML-KEM and ML-DSA in SymCrypt and CNG (generally available, November 2025); default SChannel TLS PQC negotiation is still rolling out.
- Replaced by
- ML-KEM/ML-DSA shipped in SymCrypt/CNG (GA Nov 2025); enable PQC TLS as SChannel support rolls out
- Deprecation
- Windows classical-only TLS should be supplemented with PQC proxies immediately
Technical Analysis
Microsoft Windows does not negotiate post-quantum TLS by default. As of the November 2025 update, Microsoft shipped production ML-KEM and ML-DSA in SymCrypt and the CNG/Certificate APIs (generally available in Windows 11 24H2+ and Windows Server 2025) — so the post-quantum primitives now exist on Windows. However, the SChannel TLS stack does not yet use post-quantum key exchange by default: HTTPS, RDP, SMB, and LDAP/AD over TLS still rely on classical RSA/ECDH unless PQC is explicitly enabled.
At a glance
| Full Name | Microsoft Windows |
| Category | infrastructure |
| Quantum Vulnerability | SChannel TLS uses RSA/ECDH key exchange — vulnerable to Shor's algorithm. |
| NIST Status | Microsoft shipped ML-KEM and ML-DSA in SymCrypt and CNG (generally available, November 2025); default SChannel TLS PQC negotiation is still rolling out. |
| Deprecation Timeline | Windows classical-only TLS should be supplemented with PQC proxies immediately |
| Replaced By | ML-KEM/ML-DSA shipped in SymCrypt/CNG (GA Nov 2025); enable PQC TLS as SChannel support rolls out |
Migration Guidance
Deploy PQC-capable TLS termination in front of Windows services. Use QScout to assess current Windows TLS configuration.
How Qtonic Quantum Can Help
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