Sovereign Tech Fund commits €1M+ to transition Let's Encrypt to post-quantum cryptography

The Sovereign Tech Fund has announced a commitment of over €1 million to the Internet Security Research Group (ISRG) to prepare Let's Encrypt for the post-quantum era. This initiative focuses on transitioning the widely used, free certificate authority to a new format known as Merkle Tree Certificates. This change is necessary because current digital signatures used to verify website identities could be forged by sufficiently powerful quantum computers.

To prevent the increased data overhead associated with post-quantum signatures from slowing down web connections, the project will utilize Merkle trees to batch signatures. The ISRG will research, develop, and deploy this new infrastructure through the end of 2027. The goal is to provide a production-ready, automated, and free service that maintains small authentication data sizes while providing robust quantum resistance.

Technical transition to Merkle Tree Certificates

• Signature Efficiency: Post-quantum signatures can be up to 40 times larger than current signatures; Merkle Tree Certificates mitigate this by signing a batch of certificates at once rather than signing each individually.
• Data Overhead Reduction: By using a Merkle tree structure, each certificate only needs to carry a short cryptographic proof of its inclusion in the signed batch, allowing ISRG to target authentication data under 1,000 bytes per connection.
• Implementation Roadmap: The ISRG project includes building signing and distribution software, testing in staging environments, and ensuring the system can survive data center failures while remaining compliant with browser standards.
• Standardization Alignment: The development process involves active participation in the Internet Engineering Task Force (IETF) and collaboration with browser manufacturers to define post-quantum requirements.

Why it matters

This funding secures critical digital infrastructure by ensuring that the transition to post-quantum security is automated and free for all users. By standardizing Merkle Tree Certificates, the project prevents a scenario where only well-funded entities can afford the increased bandwidth and computational costs of quantum-resistant web security.