PQC readiness beyond OpenSSL/sodium

Hi! I recently read Paragon Initiative's post "Post-Quantum Cryptography for the PHP Community" [1] and have been following the broader PQC discussions, particularly Google's and Cloudflare's migration timelines, which seem to be pulling the industry's expectations forward quite a bit. I want to stress upfront: I am not a security expert, and this question may be naive. I'm asking to understand whether there's anything that needs to be done on the language/runtime side. My working assumption has been that the heavy lifting for PQC in PHP will come through the libraries that ext/openssl and ext/sodium wrap, in other words, that once OpenSSL ships stable ML-KEM / ML-DSA / hybrid primitives and libsodium follows suit, exposing them in PHP is largely a matter of binding new functions and constants, similar to how past algorithms were added. Paragon's ext-pqcrypto and pqcrypto_compat seem to cover the gap in the meantime. What I'm less sure about is whether there are PHP-specific concerns beyond "wait for the libraries." A few things I've wondered about, though I may be framing them wrong: * Whether the substantially larger key/signature/ciphertext sizes of PQC algorithms interact badly with any internal assumptions in PHP (string handling is presumably fine, but things like stream buffer defaults, TLS-related INI defaults, or session serialization come to mind). * Whether anything in the bundled extensions that does its own crypto (PHAR signatures, password_hash, openssl_* wrappers, PHP's own TLS stream context options) will need design-level decisions rather than just new constants — e.g., how hybrid KEMs get surfaced in stream contexts, or whether PHAR will gain PQ signature support. * Whether there's an expectation that PHP tracks a minimum OpenSSL version that supports PQC by some date, and what that might mean for distros. * Whether any of this warrants an RFC-level discussion now rather than closer to 2029. Is any of the above already being tracked or discussed? Are there concerns I'm missing entirely? I'd rather ask a possibly-dumb question now than find out in 2028 that something obvious was overlooked. :-) Thanks for your time, Sebastian -- Sebastian Bergmann https://phpunit.expert Stay up to date with PHPUnit: https://phpunit.expert/newsletter