RSA vs ML-KEM: Post-Quantum Encryption Adds 30x Data [2026]

Every TLS handshake, every SSH login, and every signed software update on the internet today leans on math that a large enough quantum computer could break. That is not a hypothetical anymore. NIST finalized its first three post-quantum cryptography standards, FIPS 203, FIPS 204, and FIPS 205, on August 13, 2024, and cloud providers, browsers, and messaging apps have spent the past two years quietly swapping RSA and elliptic-curve key exchange for a new algorithm called ML-KEM. The question engineers are actually searching for in September 2026 is not whether to care about post-quantum cryptography. It is whether to switch now, what it costs in bandwidth and latency, and which parts of a stack need it first.

This comparison lines up classical public-key encryption (RSA-2048/4096 and ECC over P-256 or X25519) against ML-KEM, the NIST-standardized post-quantum key encapsulation mechanism derived from CRYSTALS-Kyber. We pull key sizes straight from FIPS 203, benchmark data from Cloudflare, Google Chrome’s engineering blog, and academic TLS studies, and real pricing from AWS and Google Cloud. No invented numbers, no guessed release dates. Where the public research does not yet answer a question cleanly, like exact Q-day timing, we say so instead of filling the gap with a made-up figure.