NCSC urges TLS 1.3 and post-quantum migration by 2031

UK NCSC says deploy hybrid post-quantum TLS 1.3 now and finish high-priority migration, including data in transit, by 2031.

The UK National Cyber Security Centre published updated administrator guidance on configuring TLS and moving toward post-quantum cryptography. It recommends TLS 1.3 with hybrid key exchange, specifically X25519MLKEM768 or SecP256r1MLKEM768 together with TLS_AES_128_GCM_SHA256, and says only correctly configured TLS 1.3 protects against quantum attacks. TLS 1.2 can still resist classical attacks when using recommended profiles but should be migrated, while SSL and TLS 1.0 and 1.1 must be disabled, and servers and clients should be patched against implementation flaws. The update aligns with published post-quantum timelines under which high-priority migration, including confidentiality of data in transit, should be completed by 2031, and it says standardized post-quantum TLS configurations are already available in well-studied libraries. Post-quantum authentication is not yet standardized for the public Web PKI, so NCSC will issue that advice later and also plans to update IPsec guidance as related RFCs are finalized. The two reports do not conflict; the second adds the 2031 deadline and planned follow-on guidance.