Homomorphic Time-Lock Puzzle Schemes

This is the repository for the paper

Towards Practical Homomorphic Time-Lock Puzzles: Applicability and Verifiability, ESORICS 2022 [Link]

by Yi Liu, Qi Wang, Siu-Ming Yiu.

Introduction

This repository provides implementations for the additively homomorphic time-lock puzzle scheme with solution space $\mathbb{Z}_n$ in [MT19] and our multiplicatively homomorphic time-lock puzzle scheme with solution space $\mathbb{Z}_n^*$.

To avoid the redundant cost of the puzzle-solving process, we provide three simple and fast protocols for both the additively HTLP scheme with the solution space $\mathbb{Z}_n$ and our multiplicatively HTLP scheme, respectively, to verify the following three properties.

1. Correctness. A puzzle solver is able to convince other parties of the correctness of the solution that he solves from a puzzle.
2. Invalidity. Upon finding that a puzzle is invalid, one can convince other parties of the invalidity of the puzzle.
3. Validity. A puzzle generator can convince other parties of the validity of the puzzle he generated.

Dependencies

This project has dependencies of NTL and OpenSSL.

Build

1. Install NTL.

2. Install libssl-dev

3. Clone the repository:

   git clone https://github.com/liu-yi/HTLP
   

4. Enter the directory

   cd HTLP
   

5. Assuming you have globally installed NTL and libssl-dev:

   make
   

6. You can test the execution by ./TestHTLP, which is defined in src/main.cpp.