Cryptanalysis of a lattice-based proxy signature scheme

TL;DR

This paper critically analyzes a recent lattice-based proxy signature scheme, revealing a forgery vulnerability that undermines its claimed security properties, thus highlighting the need for more robust cryptographic designs.

Contribution

The paper demonstrates that Jiang et al.'s proposed scheme is insecure by providing a method for an original signer to forge proxy signatures, contradicting their security claims.

Findings

The scheme is vulnerable to forgery by the original signer.

The claimed security properties of the scheme are invalid.

A concrete attack method is presented.

Abstract

A proxy signature scheme allows a proxy signer to sign messages on behalf of an original signer. Proxy signature schemes have found numerous practical applications such as grid computing, mobile agent systems and cloud applications. Recently, Jiang et al. proposed the first lattice-based proxy signature scheme and claimed that their scheme provides all the security properties of a secure proxy signature scheme. However, in this paper, we disprove their claim and show that an original signer is able to forge a proxy signature on any message.