Non-interactive Cryptographic Timestamping based on Verifiable Delay Functions

Esteban Landerreche; Marc Stevens; Christian Schaffner

Paper 2019/197

Non-interactive Cryptographic Timestamping based on Verifiable Delay Functions

Esteban Landerreche, Marc Stevens, and Christian Schaffner

Abstract

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.

Metadata

Available format(s): PDF
Publication info: Preprint. MINOR revision.
Keywords: non-interactive cryptographic timestamping universal composability verifiable delay functions time-lock cryptography
Contact author(s): esteban @ cwi nl
History: 2019-02-27: revised; 2019-02-27: received; See all versions
Short URL: https://ia.cr/2019/197
License: CC BY

BibTeX

@misc{cryptoeprint:2019/197,
      author = {Esteban Landerreche and Marc Stevens and Christian Schaffner},
      title = {Non-interactive Cryptographic Timestamping based on Verifiable Delay Functions},
      howpublished = {Cryptology {ePrint} Archive, Paper 2019/197},
      year = {2019},
      url = {https://eprint.iacr.org/2019/197}
}