Lattice Blind Signatures with Forward Security

TL;DR

This paper introduces the first lattice-based blind signature scheme that ensures forward security, protecting past signatures even if current secret keys are exposed, using binary trees and trapdoor delegation techniques.

Contribution

It presents the first forward-secure blind signature construction based on lattice assumptions, combining binary trees and trapdoor delegation for secret key evolution.

Findings

First lattice-based forward-secure blind signature scheme

Secure against secret key exposure attacks

Uses binary tree and trapdoor delegation techniques

Abstract

Blind signatures play an important role in both electronic cash and electronic voting systems. Blind signatures should be secure against various attacks (such as signature forgeries). The work puts a special attention to secret key exposure attacks, which totally break digital signatures. Signatures that resist secret key exposure attacks are called forward secure in the sense that disclosure of a current secret key does not compromise past secret keys. This means that forward-secure signatures must include a mechanism for secret-key evolution over time periods. This paper gives a construction of the first blind signature that is forward secure. The construction is based on the SIS assumption in the lattice setting. The core techniques applied are the binary tree data structure for the time periods and the trapdoor delegation for the key-evolution mechanism.