Lightweight Selective Disclosure for Verifiable Documents on Blockchain

TL;DR

This paper introduces a lightweight, privacy-preserving method for verifiable documents on blockchain using XML/JSON formats, cryptographic hashes, and Merkle trees to enable selective disclosure and efficient verification.

Contribution

It presents a novel XML and JSON-based format for selective disclosure of documents, combined with Merkle tree structures for blockchain verification, improving over existing methods.

Findings

Efficient partial signing and verification of documents.

Enhanced privacy through selective disclosure.

Improved verification efficiency using Merkle trees.

Abstract

To achieve lightweight selective disclosure for protecting privacy of document holders, we propose an XML format for documents that can hide arbitrary elements using a cryptographic hash function and salts, which allows to be partially digitally signed and efficiently verified, as well as a JSON format that can be converted to such XML. The documents can be efficiently proven to exist by representing multiple such structures as a Merkle tree and storing its root in blockchain. We show that our proposal has advantages over known methods that represent the document itself as a Merkle tree and partially hide it.