Research On UTXO Model Blockchain Privacy Protection Method Based On Zero Knowledge Proof

The rapid development of Bitcoin has completely changed the field of digital currency.It provides a new alternative to electronic payment methods such as credit card payment and online banking service.Blockchain is the technical basis of Bitcoin.Since its inception in 2009,it has attracted the attention of many industry stakeholders.The decentralized design of blockchain solves the problems of low security,poor reliability,low efficiency,and high cost in the current centralized model.From the fields of finance and healthcare to public utilities and government departments,the application of blockchain is becoming more and more extensive.However,while blockchain is developing rapidly,it is also facing more and more technical challenges.The open and transparent characteristics of blockchain cause serious privacy issues such as transaction data and network node addresses disclosure.Attackers can calculate the balance of the address,and obtain the relationship between the transaction address and the user's real identity through statistical analysis of transaction data.Therefore,it is very important to explore the privacy protection technology of blockchain.This article proposes an effective privacy protection scheme for the UTXO(Unspent Transaction Outputs)transaction model,named Block ZTP.Block ZTP can improve the anonymity of the system by hiding the transaction amount and the transfer relationship between the two parties on the premise of ensuring the decentralization of the blockchain system.This article mainly includes the following aspects:(1)Based on the UTXO transaction model,we use the Pedersen commitment based on ECC to hide the transaction amount.The Pedersen commitment based on ECC has the nature of additive homomorphism,which can be used to verify whether the amount before and after the transaction is balanced.The security of this scheme is based on the difficulty of the discrete logarithm of elliptic curve cryptography,which can prevent users from cheating and provide auditability.In addition,we use a random number and the user's private key to generate a serial number through a pseudo-random function.This serial number can uniquely identify a UTXO to prevent users from “double spending”.(2)Based on the lock script/unlock script in the UTXO transaction model,we apply the zero knowledge proof technology to the signature verification process.We generate a zero knowledge proof as an unlocking script through non-interactive zero-knowledge proof.Then the verification node verifies whether the user has the private key corresponding to the public key in the locking script through calculation.In addition,we add a random number in the proof construction process to prevent users from cheating.(3)We design a two-step fund transfer scheme to hide the transfer relationship between the transaction initiator and the transaction receiver.Refer to the idea of stealth address in Monero,we use one-time address as intermediate address.The transaction initiator transfers Bitcoin to a one-time address,then the transaction receiver transfers Bitcoin to a commonly used address.In this way,we can prevent attackers from tracing the user's transaction information and statistically analyzing the connection between the user's address and the real identity.This article describes the operating steps of the protocol of Block ZTP in detail,and combines the above improvement schemes,finally realizes the anonymity of the transaction amount and the transfer relationship between the two parties on the blockchain.