Adding post-quantum cryptography (PQC) support #52

This ticket is a sub task of the https://bugs.ruby-lang.org/issues/22068.

For the common topics which is not RubyGems specific, you can check this Ruby issue ticket. I write drb related things on this ticket.

DRb::DRbSSLSocket::SSLConfig already works with pre-generated PQC-supported ML-DSA cert/key by :SSLCertificate and :SSLPrivateKey config options.

However, drbssl server's dual/multiple certificate support are missing. An SSL server that accepts clients with either ML-DSA-NN or RSA certificates is useful in the use case of PQC migration from RSA (non-PQC) to ML-DSA (PQC). I also want DRb::DRbSSLSocket::SSLConfig#setup_certificate's option to generate ML-DSA-44, ML-DSA-65, ML-DSA-87 certificates and keys. I prepared the PR. I am going to send the PR soon.

Files to modify

Below is a list of the files that we may modify to support PQC at least.

lib/drb/ssl.rb

PQC related pull-requests

• Add post-quantum cryptography (PQC) support to SSLConfig #53
• ssl: Add :SSLContext config option to use OpenSSL::SSL::SSLContext as-is #62