We present the first treatment of non-interactive publicly-verifiable timestamping schemes in the Universal Composability framework. Similar to a simple construction by Mahmoody et al., we use non-parallelizable computational work that relates to elapsed time to avoid previous impossibility results on non-interactive timestamping. We extend these ideas to the UC framework and show how to model verifiable delay functions (VDF) related to a global clock, and non-interactive timestamping, in the UC-framework. Furthermore, we present new constructions that are substantial improvements over Mahmoody et al.’s construction, such that any forged timestamps by the adversary are now limited to within a certain time-window that depends only on its ratio to compute VDFs more quickly and the time-window of corruption. Finally, we discuss natural applications for our construction in decentralized protocols.

, , ,
Lecture Notes in Computer Science/Lecture Notes in Artificial Intelligence
Financial Cryptography and Data Security

Landerreche, E, Stevens, M.M.J, & Schaffner, C. (2020). Non-interactive Cryptographic timestamping through based on Verifiable Delay Functions. In Lecture Notes in Computer Science/Lecture Notes in Artificial Intelligence.