Foundations of Timed-Release Cryptography

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. 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: Timed-release cryptography suffers from an extreme lack of candidate schemes, and 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).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 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, and (3) construct concrete such schemes offering a wide range of security and functionality guarantees. 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.""