NTT Corporation, in collaboration with ETH Zurich, UC Berkeley, Aalto University, Bocconi University, and JPMorgan, has developed “Ringtail,” the world’s first two-round post-quantum threshold digital signature system based on standard lattice-based security assumptions. The system demonstrated digital signature generation across servers spanning five continents in an average of 2.5 seconds, marking a significant milestone in building secure infrastructure for applications such as e-voting, finance, and decentralized systems.
The Ringtail protocol distributes signing authority across multiple users and enables a valid signature only when a minimum threshold of participants collaborate. Unlike existing post-quantum schemes, Ringtail combines provable security under the widely trusted Learning With Errors (LWE) assumption with low latency and minimal communication rounds. The protocol outperforms previous designs in both efficiency and practicality, completing online signing in as little as 0.6 seconds, even in high-latency conditions such as between Japan and Brazil.
The successful proof-of-concept experiment was conducted across eight data centers worldwide and demonstrates that Ringtail is suitable for real-world deployments involving geographically distributed stakeholders. The technology is intended for use in systems requiring multi-party approval, such as high-value financial operations, cold storage withdrawals in cryptocurrency platforms, and decentralized governance. NTT plans to extend this approach to more complex cryptographic tools, including group signatures and secure access controls for quantum-resilient systems.
- Ringtail is the first two-round, post-quantum threshold signature using standard assumptions (LWE)
- Global test across 5 continents confirmed 2.5-second signature generation
- Online signing completed in ~0.6 seconds—comparable to physical network latency
- Designed for high-security applications: finance, crypto, e-voting, and decentralized governance
- Joint research led by NTT with ETH Zurich, UC Berkeley, Aalto, Bocconi, and JPMorgan
“We expect this technology to be deployed for secure, multi-user authentication and permission applications in systems such as electronic voting, government services, and finance,” said NTT in its announcement.
