Emircan YILDIRIM, Kerim Eser AFŞAR, Ramazan BEKTAŞ

Merkez Bankası Dijital Para Birimi: Tasarım ve Protokol Mekanizmaları Bağlamında Karşılaştırmalı Bir Analiz

Bitcoin ile başlayan kripto para ekosistemi ve büyük teknoloji şirketlerinin kendi ödeme sistemlerini kurma girişimleri, merkez bankalarının para üzerindeki tekel haklarını tehdit etmeye başlamıştır. Merkez bankalarının bu gelişmelere olan nihai tepkisi merkez bankası dijital parasıdır (CBDC). Bu çalışmada blok zinciri ağlarında kullanılan alternatif protokol mekanizmalarının, verimlilik, güvenlik ve mahremiyet bağlamında karşılaştırması CBDC literatürünü kapsayacak şekilde yapılmıştır. Çalışmanın amacı protokol ve tasarım özelliklerinin “yeni finansal mimari” içindeki işlevini analiz etmektir. Bu bağlamda çalışmada, CBDC tasarımında bahsi geçen protokollerin işleyişini ayrıntılandırıyoruz. Araştırma kapsamında blok zinciri teknolojisi uzmanlarıyla yarı yapılandırılmış mülakat tekniği kullanılarak veriler toplanmış ve karşılaştırmalı analize tabi tutulmuştur. Karşılaştırmalı analiz yöntemiyle elde edilen bulgulara göre CBDC tasarımında Proof of Authority (POA) protokolünün kullanılması, merkez bankalarına finansal sistemin tümü bağlamında bir gözetim yapabilme şansı tanıyarak bireysel mahremiyeti tamamen ortadan kaldırabilir. Çevrim dışı ödeme (OPS) protokolünün kullanılmadığı durumlarda CBDC’nin amaçlarından biri olan finansal kapsayıcılık işlevsiz kalabilir. Proof of Work (PoW) ve Proof of Stake (PoS) protokollerinin varyasyonlarının kullanılması ise ölçekleme probleminin ortaya çıkmasına neden olabilir. CBDC tasarımlarında kullanılan protokollerin güçlü yönleri dikkate alınarak hibrit bir protokol oluşturulabilir. Protokol yapısının güçlü olması para politikası bağlamında CBDC’nin işlevselliğini arttırabilir. CBDC protokolleri literatürde çoğunlukla verimlilik ve güvenlik boyutlarıyla tartışılmaktadır. Tartışmaya mahremiyet boyutunun da dâhil edilmesi gerektiğini iddia ediyoruz.

Anahtar Kelimeler:

CBDC, konsensüs protokol, verimlilik, blok zinciri

Central Bank Digital Currency: A Comparative Analysis in the Context of Design and Protocol Mechanisms

The ecosystem of crypto money that started with Bitcoin and the attempts of big technology companies to establish their own payment systems began to threaten the monopoly rights of Central Banks on money. The ultimate response of the Central Bank towards these developments is the central bank digital currency (CBDC). In this study, a comparison of an alternative protocol used in blockchain networks with respect to efficiency, security, and privacy that is compatible with the CBDC literature will be provided. The intention of this study is to analyze the function of protocol and design features in the “new financial architecture”. In this context, we delve into the operation of the protocols mentioned in the CBDC design. Within the scope of this research, data were collected by using semi-structured interview technique with blockchain technology experts and subjected to comparative analysis. According to the findings obtained by the comparative analysis method, the use of the Proof of Authority (POA) protocol in the CBDC design can completely eliminate individual privacy by giving an opportunity to the central banks to oversee the entire financial system. In the absence of the offline payment (OPS) protocol, financial inclusion, one of the objectives of the CBDC, may become dysfunctional. Using variations of Proof of Work (PoW) and Proof of Stake (PoS) protocols might give rise to scaling problems. A hybrid protocol can be created by considering the strengths of the protocols used in CBDC designs. A strong protocol structure can significantly increase the functionality of the CBDC in the context of monetary policy. CBDC protocols are frequently discussed in the literature regarding their efficiency and security dimensions. We assume that the privacy dimension should also be included in the discussion.

Keywords:

CBDC, consensus protocols, efficience, blockchain,

PDF

___

S. Nakamoto, “Bitcoin: A Peer-to-Peer Electronic Cash System”, Decentralized Business Review, 21260, 1-9, 2008.
P. K. Ozili, “Central bank digital currency research around the World: a review of literatüre”, Journal of Money Laundering Control, 2022.
F. Allen, X. Gu, J. Jagtiani, “Fintech, cryptocurrencies, and CBDC: Financial structural transformation in China”, Journal of International Money and Finance, 124, 102625, (2022).
P. K. Ozili, “Central bank digital currency in Nigeria: opportunities and risks”, Available at SSRN, (2021).
S. L. Náñez Alonso, M. A. Echarte Fernández, D. Sanz Bas, J. Kaczmarek, “Reasons fostering or discouraging the implementation of central bank-backed digital currency: A review”, Economies, 8(2), 41, 2020.
S. Haber, W. S. Stornetta, “How to Time-Stamp a Digital Document”, In Conference on the Theory and Application of Cryptography, Cilt 537, Editör: Menezes A. J., Manstone S. A., Springer, Berlin, Heidelberg, Lecture Notes in Computer Science, 437-455, 1990.
C. Dwork, M. Naor. “Pricing Via Processing or Combatting Junk Mail”, In Annual International Cryptology Conference, Cilt 470, Editör: Brickell E. F., Springer, Berlin, Heidelberg, Lecture Notes in Computer Science, 139-147, 1992.
D. Chaum, “Security Without İdentification: Transaction Systems to Make Big Brother Obsolete”, Communications of the ACM, 28(10), 1030-1044, 1985.
G. Bashar, G. Hill, S. Singha, P. Marella, G.G. Dagher, J. Xiao, “Contextualizing Consensus Protocols in Blockchain: A Short Survey”, 2019 First IEEE International Conference on Trust, Privacy and Security in Intelligent Systems and Applications (TPS-ISA), IEEE, Lahor-Pakistan, 190195, 1921 December, 2019.
N. Chaudhry, M. M. Yousaf, “Consensus Algorithms in Blockchain: Comparative Analysis, Challenges and Opportunities”, In 2018 12th International Conference on Open Source Systems and Technologies (ICOSST), IEEE, Lahor-Pakistan, 5463, 1921 December, 2018.
Q. Wang, J. Huang, S. Wang, Y. Chen, P. Zhang, L. He, “A Comparative Study of Blockchain Consensus Algorithms”, In Journal of Physics: Conference Series, 1437(2020), 332-339, 2020.
A. Baliga, “Understanding Blockchain Consensus Models”, Persistent, 4(1), 1-17, 2017.
D. Mingxiao, M. Xiaofeng, Z. Zhe, W. Xiangwei, C. Qijun, “A Review on Consensus Algorithm of Blockchain” In 2017 IEEE International Conference on Systems, Man, and Cybernetics (SMC), IEEE, Banff, AB, Canada, 25672572, 0508 October, 2017.
O. Demir, H. Odabaşi, “Merkez Bankası Dijital Para Sisteminin Avantaj ve Dezavantajları Neler Olabilir? Erciyes Üniversitesi İktisadi ve İdari Bilimler Fakültesi Dergisi, (61), 199-222, 2022.
İ, Al, H. Akyazı, “Merkez Bankası Dijital Parası ve Para Politikasına Yansımaları”, Abant İzzet Baysal Üniversitesi Sosyal Bilimler Enstitüsü Dergisi, 19(3), 573-593, 2019.
K. Sebahattin, “Paranın Dijitalleşmesi ve Merkez Bankası Dijital Para Olasılığı”, Bitlis Eren Üniversitesi İktisadi Ve İdari Bilimler Fakültesi Akademik İzdüşüm Dergisi, 5(2), 196-204, 2020.
N. Öztürk, A. Okan, “Paranın Dönüşümünde Yeni Bir Evre: Merkez Bankası Dijital Parası”, Uluslararası Muhasebe ve Finans Araştırmaları Dergisi, 3(2), 85-104, 2021.
Y. Toroman, “E-Para ve Tokenler (Dijital Türk Aakçesi) İle Borçlanma: Dijital Türk Lirası (DTL) Üzerine Bir Çalışma”, Bilge Uluslararası Sosyal Araştırmalar Dergisi, 5(2), 124-134, 2019.
G. Calle, D. Eidan, “Central Bank Digital Currency: An Innovation in Payments”, R3 White Paper, 1-20, 2020.
D. Priyadarshini, S. Kar, “Central Bank Digital Currency (CBDC): Critical Issues and the Indian Perspective”, Institute of Economic Growth Working Paper, No. 444, 2021.
M. D. Bordo, A. T. Levin, “Central Bank Digital Currency and the Future of Monetary Policy”, National Bureau of Economic Research, Working Paper, No 23711, 1-30, 2017.
R. Auer, R. Böhme, “The Technology of Retail Central Bank Digital Currency”, BIS Quarterly Review, March, 85-100, 2020.
S. M. Davoodalhosseini, “Central bank digital currency and monetary policy”, Journal of Economic Dynamics and Control, 104150, (2021).
G. Ünal, Ç. Uluyol, “Blok zinciri teknolojisi”, Bilişim Teknolojileri Dergisi, 13(2), 167-175, 2020.
Zhang, T., & Huang, Z. (2021). Blockchain and Central Bank Digital Currency. ICT Express 8, 264–270, 2022.
R. Auer, G. Cornelli, J. Frost, “Rise of the Central Bank Digital Currencies: Drivers, Approaches and Technologies”, Bank for International Settlements Working Paper, 1-42, 2020.
N. Bilotta, F. Botti, The (Near) Future of Central Bank Digital Currencies: Risks and Opportunities for the Global Economy and Society, Bern, İsviçre, Peter Lang International Academic Publishers, 2021.
İnternet: D. Niepelt, Central Bank Digital Currency: Considerations, Projects, Outlook, https://voxeu.org/article/central-bank-digital-currency-considerations-projects-outlook, 10.06.2022.
W. Tsai, Z. Zhao, C. Zhang, L. Yu, E. Deng, “A Multi-Chain Model for CBDC”, 2018 5th International Conference on Dependable Systems and Their Applications, Dalian, China, 2534, 2223 September, 2018.
H. Sun, H. Mao, X. Bai, Z. Chen, K. Hu, W. Yu, “Multi-Blockchain Model for Central Bank Digital Currency”, 2017 18th International Conference on Parallel and Distributed Computing, Applications and Technologies, Taipei, Taiwan, 360367, 1820 December, 2017.
J. Zhang, R. Tian, Y. Cao, X. Yuan, Z. Yu, X. Yan, X. Zhang, “A Hybrid Model for Central Bank Digital Currency Based on Blockchain”, IEEE Access, 9, 53589-53601, 2021.
J. Lovejoy, C. Fields, M. Virza, T. Frederick, D. Urness, K. Karwaski, N. Narula, “A High Performance Payment Processing System Designed for Central Bank Digital Currencies”, Cryptology ePrint Archive, 1-35, 2022.
H. Jung, D. Jeong, “Blockchain Implementation Method for Interoperability Between CBDCs”, Future Internet, 13(5), 133, 2021.
J. Han, J. Kim, A. Youn, J. Lee, Y. Chun, J. Woo, J. W. K. Hong, “Cos-CBDC: Design and Implementation of CBDC on Cosmos Blockchain”, 22nd Asia-Pacific Network Operations and Management Symposium, Tainan, Taiwan, 303308, 0810 September, 2021.
D. T. Sasongko, S. Yazid, “Integrated DLT and non-DLT System Design for Central Bank Digital Currency”, Proceedings of the 5th International Conference on Sustainable Information Engineering and Technology, New York, United State,171176, 1617 November, 2020.
S. Kumar, “Permission Blockchain Network Based Central Bank Digital Currency”, 2021 IEEE 4th International Conference on Computing, Power and Communication Technologies, Kuala Lumpur, Malaysia, 16, 2426 September, 2021.
S. Maharjan, K. Ko, C. Kang, J. Woo, J. W. Hong, “A Study of CBDC Model Applicable for the Current Banking Environment”, KNOM Conference 2020, Daejeon, South Korea, 5660, 2020.
M. Christodorescu, W. C. Gu, R. Kumaresan, M. Minaei, M. Ozdayi, B. Price, M. Zamani, “Towards a Two-Tier Hierarchical Infrastructure: an Offline Payment System for Central Bank Digital Currencies”, arXiv preprint:2012.08003, 1-21, 2020.
F. Saleh, “Blockchain Without Waste: Proof-of-stake”, The Review of Financial Studies, 34(3), 1156-1190, 2021.
E. Deirmentzoglou, G. Papakyriakopoulos, C. Patsakis, “A Survey on Long-Range Attacks for Proof of Stake Protocols”, IEEE Access, 7, 28712-28725, 2019.
S. Kardaş, “Blokzincir Teknolojisi: Uzlaşma Protokolleri”, Dicle Üniversitesi Mühendislik Fakültesi Mühendislik Dergisi, 10(2), 481-496, 2019.
C. N. Samuel, S. Glock, F. Verdier, P. Guitton-Ouhamou, “Choice of Ethereum Clients for Private Blockchain: Assessment from Proof of Authority Perspective”, 2021 IEEE International Conference on Blockchain and Cryptocurrency, Sydney, Australia, 15, 0306 May, 2021.
D. Ongaro, J. Ousterhout, “In Search of an Understandable Consensus Algorithm”, (extended version), 2013.
Y. Gao, H. Nobuhara, “A Proof of Stake Sharding Protocol for Scalable Blockchains”, Proceedings of the Asia-Pacific Advanced Network, 44(1), 13-16, 2017.
U. Gallersdörfer, L. Klaaßen, C. Stoll, “Energy Consumption of Cryptocurrencies Beyond Bitcoin”, Joule, 4(9), 1843-1846, 2020.
O. Vashchuk, R. Shuwar, “Pros and Cons of Consensus Algorithm Proof of Stake. Difference in the Network Safety in Proof of Work and Proof of Stake”, Electronics and Information Technologies, 9(9), 106-112, 2018.
C. Ganesh, C. Orlandi, D. Tschudi, “Proof-of-Stake Protocols for Privacy-Aware Blockchains”, Annual International Conference on the Theory and Applications of Cryptographic Techniques, Darmstadt, Germany, 690719,1923 May, 2019.
G. Fanti, L. Kogan, P. Viswanath, “Economics of Proof-of-Stake Payment Systems”, Working Paper, 2019.
R. Zhang, W. K. V. Chan, “Evaluation of Energy Consumption in Block-chains with Proof of Work and Proof of Stake”. Journal of Physics: Conference Series, 1584(1), 2020.
X. Zheng, W. Feng, “Research on Practical Byzantine Fault Tolerant Consensus Algorithm Based on Blockchain”, Journal of Physics: Conference Series, 1802(3), 2021.
S. M. S. Saad, R. Z. R. M. Radzi, “Comparative Review of the Blockchain Consensus Algorithm Between Proof of Stake (PoS) and Delegated Proof of Stake (DPoS)”, International Journal of Innovative Computing, 10(2), 27-32, 2020.
T. Do, T. Nguyen, H. Pham, “Delegated Proof of Reputation: A Novel Blockchain Consensus”, Proceedings of the 2019 International Electronics Communication Conference, Okinawa, Japan, 9098, 0709 July, 2019.
S. De Angelis, L. Aniello, R. Baldoni, F. Lombardi, A. Margheri, V. Sassone, “PBFT vs proof-of-authority: Applying the CAP Theorem to Permissioned Blockchain”, İtalian Conference on Cyber Security, Milan, İtaly, 26 February, 2018.
A. Avasthi, A. Saxena, “Two Hop Blockchain Model: Resonating Between Proof of Work (PoW) and Proof of Authority (PoA)”, International Journal of Information Systems & Management Science, 1(1), 128-131, 2018.
J. F. Paris, D. D. Long, “Pirogue, a lighter dynamic version of the Raft distributed consensus algorithm”, 2015 IEEE 34th International Performance Computing and Communications Conference, Nanjing, China, 18, 1416 December, 2015.