Blockchain Stealth Address Schemes

In a blockchain system, address is an essential primitive which is used in transaction. The $\textit{Stealth Address}$, which has an underlying address info of two public keys ($A,B$ ), was developed by Monero blockchain in 2013, in which a one-time public key is used as the transaction destination, to protect the recipient privacy. At almost same time, $\textit{hierarchical deterministic wallets}$ scheme was proposed as $\textit{bip-32}$ for Bitcoin, which makes it possible to share an $\textit{extended public key}$ ($K,c$) between sender and receiver, where $K$ is a public key and $c$ is a 256-bits chain code, and only receiver knows the corresponding private key of this $K$. With the $\textit{bip-32}$ scheme, the sender may derive the child public key $K_i$ with the child number $i$ by him/herself, without needing to request a new address for each payment from the receiver, make each transaction have a different destination key for privacy. This paper introduces an improved stealth address scheme which has an underlying address data of $(A_i,B_i,i)$, where $i$ is a child number and $i\in [0,2^{31}-1]$. The sender gets the receiver’s address info $(A_i,B_i,i)$, generates a random secret number $r\in [0,2^{64}-1]$ and calculate a Pedersen commitment $C=A_iB_ih^{R^{\u27}.x}$ where $R^{\u27}=B_i^r$, then the sender may use this commitment $C$ or $Hash(C)$ as the destination key for the output and packs the $(R,i)$ somewhere into the transaction. This improved stealth address scheme makes it possible to manage multiple stealth addresses in one wallet, therefore the user is able to share different addresses for different senders

The Evolution of Embedding Metadata in Blockchain Transactions

The use of blockchains is growing every day, and their utility has greatly expanded from sending and receiving crypto-coins to smart-contracts and decentralized autonomous organizations. Modern blockchains underpin a variety of applications: from designing a global identity to improving satellite connectivity. In our research we look at the ability of blockchains to store metadata in an increasing volume of transactions and with evolving focus of utilization. We further show that basic approaches to improving blockchain privacy also rely on embedding metadata. This paper identifies and classifies real-life blockchain transactions embedding metadata of a number of major protocols running essentially over the bitcoin blockchain. The empirical analysis here presents the evolution of metadata utilization in the recent years, and the discussion suggests steps towards preventing criminal use. Metadata are relevant to any blockchain, and our analysis considers primarily bitcoin as a case study. The paper concludes that simultaneously with both expanding legitimate utilization of embedded metadata and expanding blockchain functionality, the applied research on improving anonymity and security must also attempt to protect against blockchain abuse.Comment: 9 pages, 6 figures, 1 table, 2018 International Joint Conference on Neural Network

Stealth address and key management techniques in blockchain systems

Bitcoin is an open source payment system with a market capitalization of about 15 G$. During the years several key management solutions have been proposed to enhance bitcoin. The common characteristic of these techniques is that they allow to derive public keys independently of the private keys, and that these keys match. In this paper we overview the historical development of such techniques, specify and compare all major variants proposed or used in practical systems. We show that such techniques can be designed based on 2 distinct ECC arithmetic properties and how to combine both. A major trend in blockchain systems is to use by Stealth Address (SA) techniques to make different payments made to the same payee unlikable. We review all known SA techniques and show that early variants are less secure. Finally we propose a new SA method which is more robust against leakage and against various attacks

The Evolution of Embedding Metadata in Blockchain Transactions

The use of blockchains is growing every day, and their utility has greatly expanded from sending and receiving crypto-coins to smart-contracts and decentralized autonomous organizations. Modern blockchains underpin a variety of applications: from designing a global identity to improving satellite connectivity. In our research we look at the ability of blockchains to store metadata in an increasing volume of transactions and with evolving focus of utilization. We further show that basic approaches to improving blockchain privacy also rely on embedding metadata. This paper identifies and classifies real-life blockchain transactions embedding metadata of a number of major protocols running essentially over the bitcoin blockchain. The empirical analysis here presents the evolution of metadata utilization in the recent years, and the discussion suggests steps towards preventing criminal use. Metadata are relevant to any blockchain, and our analysis considers primarily bitcoin as a case study. The paper concludes that simultaneously with both expanding legitimate utilization of embedded metadata and expanding blockchain functionality, the applied research on improving anonymity and security must also attempt to protect against blockchain abuse