Foundations of Timed-Release Cryptography

Introduction

Cryptography has repeatedly revolutionized modern technology via its "easy-or-infeasible" design paradigm, classifying computations as either "easy" or "infeasible". Nowadays, however, this foundational paradigm is insufficient for a host of rapidly evolving applications, and a fine-grained accounting of sequential timing guarantees is urgently needed.

Timed-Release Cryptography

This has recently led to substantial interest in the classic yet insufficiently explored vision of timed-release cryptography, enabling cryptographic systems to rely on such guarantees realistically. Despite the significant attention, the vision of timed-release cryptography is still alarmingly far, and the landscape of our current knowledge must rapidly change to facilitate its deployment.

Current Challenges

• Timed-release cryptography suffers from an extreme lack of candidate schemes.
• The security of its main candidates is provided directly by assumption, with essentially no supporting evidence other than the lack of successful "speed-up" attacks.

Proposal Objectives

This proposal aims to establish robust foundations for timed-release cryptography by obtaining an in-depth understanding of the computational landscape, building blocks, and schemes required for realizing its premise. Specifically, I plan to direct our effort towards addressing the following three fundamental objectives, which span a broad and interdisciplinary flavor of research directions:

1. Explore sources of computational hardness that enable us to base timed-release cryptography on the hardness of well-studied problems.
2. Identify the extents to which timed-release primitive building blocks require cryptographic structure and can be utilized in designing more complex schemes.
3. Construct concrete such schemes offering a wide range of security and functionality guarantees.

Conclusion

I strongly believe that substantial progress towards our objectives will enable us to realize the premise of timed-release cryptography and will have a long-lasting impact on cryptography.