Experiment with post-quantum cryptography today

This post introduces experimental support for X25519Kyber512Draft00 and X25519Kyber768Draft00 hybrid post-quantum key agreements on test domains. It details the performance characteristics of Kyber compared to classical key agreements, the use of hybrids for enhanced security, and provides open-sourced forks of BoringSSL and Go with support for these agreements. The post also includes on-the-wire analysis of TLS 1.3 handshakes with and without post-quantum key agreements, and discusses the underlying cryptographic details and differences between the Go and BoringSSL implementations.