Cloudflare Workers Adds Opt-In ML-KEM and ML-DSA Post-Quantum Cryptography

Cloudflare Workers has added opt-in Web Crypto support for ML-KEM key encapsulation and ML-DSA digital signatures, implementing parts of the draft Modern Algorithms in the Web Cryptography API proposal. Developers must enable the webcrypto_modern_algorithms compatibility flag to access the experimental APIs, which include encapsulation, decapsulation, public-key derivation, capability detection, and JWK import/export. The implementation uses BoringSSL in the open-source workerd runtime; ML-KEM-512 is unavailable because the bundled BoringSSL version does not expose it.

The broader Web Platform Incubator Community Group proposal covers additional algorithms, including hybrid key encapsulation, SLH-DSA signatures, authenticated encryption, hashing, message authentication, and Argon2 key derivation. It remains an unofficial draft, not a W3C Standard, and does not establish confirmed browser deployment or consistent support across runtimes. Cloudflare emphasizes that these primitives are building blocks, not a complete post-quantum migration path: integrations with HPKE, OHTTP, and JOSE/JWT still require work. Organizations evaluating adoption should account for API instability, runtime compatibility, and protocol integration before treating the feature as production-ready migration coverage.