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1. Version++: Cryptocurrency Blockchain Handshaking With Software Assurance

   https://doi.org/10.1109/CCNC51644.2023.10059985  

   Sarker, Arijet ; Wuthier, Simeon ; Kim, Jinoh ; Kim, Jonghyun ; Chang, Sang-Yoon ( January 2023 , IEEE Consumer Communications & Networking Conference (CCNC))

   Cryptocurrency software implements the cryptocurrency operations, including the distributed consensus protocol and the peer-to-peer networking. We design a software assurance scheme for cryptocurrency and advance the cryptocurrency handshaking protocol. Since we focus on Bitcoin (the most popular cryptocurrency) for implementation and integration, we call our scheme Version++, built on and advancing the current Bitcoin handshaking protocol based on the Version message. Our Version++ protocol providing software assurance is distinguishable from the previous research because it is permissionless, distributed, and lightweight to fit its cryptocurrency application. Our scheme is permissionless since it does not require a centralized trusted authority (unlike the remote software attestation techniques from trusted computing); it is distributed since the peer checks the software assurances of its own peer connections; and it is designed for efficiency/lightweight due to the dynamic nature of the peer connections and the large-scale broadcasting in cryptocurrency networking. Utilizing Merkle Tree for the efficiency of the proof verification, we implement and test Version++ on Bitcoin software and conduct experiments in an active Bitcoin node prototype connected to the Bitcoin Mainnet. Our prototype-based performance analyses demonstrate the lightweight design of Version++. The peer-specific verification grows logarithmically with the number of software files in processing time and in storage. In addition, the Version++ verification overhead is small compared to the overall handshaking process; our measured overhead of 2.22% with minimal networking latency between the virtual machines provides an upper bound in the real-world networking with greater handshaking duration, i.e., the relative Version++ overhead in the real world with physically separate machines will be smaller. 

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2. From Slow Propagation to Partition: Analyzing Bitcoin Over Anonymous Routing

   Sakib, Nazmus ; Wuthier, Simeon ; Zhou, Xiaobo ; Chang, Sang-Yoon ( May 2024 , IEEE International Conference on Blockchain and Cryptocurrency ICBC)

   Cryptocurrency is designed for anonymous financial transactions to avoid centralized control, censorship, and regulations. To protect anonymity in the underlying P2P networking, Bitcoin adopts and supports anonymous routing of Tor, I2P, and CJDNS. We analyze the networking performances of these anonymous routing with the focus on their impacts on the blockchain consensus protocol. Compared to non-anonymous routing, anonymous routing adds inherent-by-design latency performance costs due to the additions of the artificial P2P relays. However, we discover that the lack of ecosystem plays an even bigger factor in the performances of the anonymous routing for cryptocurrency blockchain. I2P and CJDNS, both advancing the anonymous routing beyond Tor, in particular lack the ecosystem of sizable networking-peer participation. I2P and CJDNS thus result in the Bitcoin experiencing networking partitioning, which has traditionally been researched and studied in cryptocurrency/blockchain security. We focus on I2P and Tor and compare them with the non-anonymous routing because CJDNS has no active public peers resulting in no connectivity. Tor results in slow propagation while I2P yields soft partition, which is a partition effect long enough to have a substantial impact in the PoW mining. To better study and identify the latency and the ecosystem factors of the cryptocurrency networking and consensus costs, we study the behaviors both in the connection manager (directly involved in the P2P networking) and the address manager (informing the connection manager of the peer selections on the backend). This paper presents our analyses results to inform the state of cryptocurrency blockchain with anonymous routing and discusses future work directions and recommendations to resolve the performance and partition issues. 

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3. Lightweight and Identifier-Oblivious Engine for Cryptocurrency Networking Anomaly Detection

   https://doi.org/10.1109/TDSC.2022.3152937  

   Fan, Wenjun ; Hong, Hsiang-Jen ; Kim, Jinoh ; Wuthier, Simeon James ; Nakashima, Makiya ; Zhou, Xiaobo ; Chow, Edward ; Chang, Sang-Yoon ( February 2022 , IEEE Transactions on Dependable and Secure Computing)

   The distributed cryptocurrency networking is critical because the information delivered through it drives the mining consensus protocol and the rest of the operations. However, the cryptocurrency peer-to-peer (P2P) network remains vulnerable, and the existing security approaches are either ineffective or inefficient because of the permissionless requirement and the broadcasting overhead. We design a Lightweight and Identifier-Oblivious eNgine (LION) for the anomaly detection of the cryptocurrency networking. LION is not only effective in permissionless networking but is also lightweight and practical for the computation-intensive miners. We build LION for anomaly detection and use traffic analyses so that it minimally affects the mining rate and is substantially superior in its computational efficiency than the previous approaches based on machine learning. We implement a LION prototype on an active Bitcoin node to show that LION yields less than 1% of mining rate reduction subject to our prototype, in contrast to the state-of-the-art machine-learning approaches costing 12% or more depending on the algorithms subject to our prototype, while having detection accuracy of greater than 97% F1-score against the attack prototypes and real-world anomalies. LION therefore can be deployed on the existing miners without the need to introduce new entities in the cryptocurrency ecosystem. 

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4. Robust P2P networking connectivity estimation engine for permissionless Bitcoin cryptocurrency

   https://doi.org/10.1016/j.comnet.2022.109436  

   Hong, Hsiang-Jen ; Fan, Wenjun ; Wuthier, Simeon ; Kim, Jinoh ; Chow, C. Edward ; Zhou, Xiaobo ; Chang, Sang-Yoon ( December 2022 , Computer networks)

   Blockchain relies on the underlying peer-to-peer (P2P) networking to broadcast and get up-to-date on the blocks and transactions. Because of the blockchain operations’ reliance on the information provided by P2P networking, it is imperative to have high P2P connectivity for the quality of the blockchain system operations and performances. High P2P networking connectivity ensures that a peer node is connected to multiple other peers providing a diverse set of observers of the current state of the blockchain and transactions. However, in a permissionless Bitcoin cryptocurrency network, using the peer identifiers – including the current approach of counting the number of distinct IP addresses and port numbers – can be ineffective in measuring the number of peer connections and estimating the networking connectivity. Such current approach is further challenged by the networking threats manipulating identities. We build a robust estimation engine for the P2P networking connectivity by sensing and processing the P2P networking traffic. We take a systematic approach to study our engine and analyze the followings: the different components of the connectivity estimation engine and how they affect the accuracy performances, the role and the effectiveness of an outlier detection to enhance the connectivity estimation, and the engine’s interplay with the Bitcoin protocol. We implement a working Bitcoin prototype connected to the Bitcoin mainnet to validate and improve our engine’s performances and evaluate the estimation accuracy and cost efficiency of our connectivity estimation engine. Our results show that our scheme effectively counters the identity-manipulations threats, achieves 96.4% estimation accuracy with a tolerance of one peer connection, and is lightweight in the overheads in the mining rate, thus making it appropriate for the miner deployment. 

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5. A Survey ofNFC Mobile Payment: Challenges and Solutions using Blockchain and Cryptocurrencies

   https://doi.org/10.1109/DSA51864.2020.00018  

   Li, Dongcheng ; Wong, W. Eric ; Chau, Matthew ; Pan, Sean ; Koh, Liang Seng ( November 2020 , The 7th International Conference on Dependable Systems and Their Applications)

   Near-field communication (NFC) is one of the essential technologies in the Internet of Things (IoT) that has facilitated mobile payment across different services. The technology has become increasingly popular, as cryptocurrencies like Bitcoin have revolutionized how payment systems can be designed. However, this technology is subject to security problems, such as man-in-the-middle attacks, double-spending, and replay attacks, raising the need to incorporate other solutions such as blockchain technology. Concerns about the security and privacy of payments using NFC technology raise the need to adopt blockchain-based cryptocurrency payment. For instance, NFC payment has been criticized for a lack of measures to counter potential attacks, such as brute force or double-spending. Thus, incorporating blockchain technology is expected to improve the security features of the NFC mobile payment protocol and improve user experience. Blockchain technology has been praised for enabling fair payment, as it permits direct transactions without engaging a third party. Therefore, integrating blockchain cryptocurrency in IoT devices will revolutionize the NFC payment method and provide value transfer using IoT devices. Combining NFC with blockchain technology and cryptocurrencies is necessary to address security and privacy problems. The purpose of this paper is to explore the potential behind incorporating blockchain technology and cryptocurrencies like Bitcoin in the NFC payment protocol. 

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