A Post-Quantum Future for Let's Encrypt

Let's Encrypt plans to adopt Merkle Tree Certificates (MTCs) to enable post-quantum-safe web security without the performance costs of traditional post-quantum signature algorithms. Standard post-quantum signatures like ML-DSA are too large for typical TLS handshakes, causing connection failures and slowdowns, so MTCs offer an alternative approach where a single signature covers an entire batch of certificates. This strategy addresses the increasingly urgent timeline set by government mandates and major tech companies to transition to post-quantum cryptography by 2030-2035.