Threshold Trapdoor Functions and Their Applications

TL;DR

This paper introduces threshold trapdoor functions (TTDFs), constructs threshold and revocation encryption schemes from them, and demonstrates their practicality and security under standard assumptions.

Contribution

The paper defines TTDFs, provides generic constructions for threshold and revocation encryption, and instantiates TTDFs under DDH and LWE assumptions, showing improved practicality.

Findings

Schemes are practical based on experimental results.

Threshold and revocation encryptions outperform existing schemes.

TTDFs can be instantiated under standard cryptographic assumptions.

Abstract

We introduce a cryptographic primitive named threshold trapdoor functions (TTDFs), from which we give generic constructions of threshold and revocation encryptions under adaptive corruption model. Then, we show TTDF can be instantiated under the decisional Diffie-Hellman (DDH) assumption and the learning with errors (LWE) assumption. By combining the instantiations of TTDF with the generic constructions, we obtain threshold and revocation encryptions which compare favorably over existing schemes. The experimental results show that our proposed schemes are practical.