Simplifying Access to Blockchain Data Across Multiple Networks

Table of Links Abstract and 1 Introduction 2 Background and Related Work and 2.1 From Bitcoin to Blockchains 2.2 Open and Permissionless Blockchains 2.3 Interoperability Between Blockchains 3 Cross-Chain Query Language and 3.1 Integrated Data Model 3.2 Grammar and Query Processing Architecture 4 Evaluation of Implementation Feasibility and 4.1 Software and Hardware Configuration 4.2 Query Processing 4.3 Discussion 5 Conclusion and Outlook, Acknowledgment, and References 4.3 Discussion The prototype provides uniform data access to OPB, such as the retrieval of asset and data transfers across multiple blockchains. As per the defined grammar, data access is standardized, facilitating statements that involve one or more blockchains. For meaningful utilization of blockchain properties, it is essential to operate blockchain nodes locally, which can involve significant time and cost for initial synchronizations. The architecture of the data model follows a data integration approach, where data conforming to well-known OPB can be stored by populating pertinent classes. In contrast, merely relying on multiple individual data models would fail to address the issue at hand. Due to the generic and unifying approach, the prototype in its current form has limited support for advanced concepts specific to individual OPB. For instance, calculating transaction fees involving additional utility tokens falls outside the scope of this model. Functionality-wise, limitations concern the processing of queries with filters. Currently, the prototype is constrained to the sequential application of filters with equality comparisons. In addition, the processing is limited to the classes and attributes present in the data model. In future development, further blockchain-specific processing logic and attributes could be added to the architecture and the data model, respectively. At this point, the prototype demonstrates the general feasibility of a domain-specific language that supports multiple blockchains. Regarding atomicity, it is supported on a technical level for query transactions within the data model, however, the API-based access approach does not allow for atomicity guarantees that depend on the software node implementations of different blockchains. Oftentimes, APIs do not provide specific atomicity or strong consistency guarantees and instead rely on eventual consistency. For this reason, access through APIs limits the possibility of strong guarantees for the prototype. 5 Conclusion and Outlook This paper presents a cross-chain query language grammar, data model, and processing architecture aimed at facilitating uniform data access across multiple blockchains. The approach enables homogeneous data access, query standardization, addressing multiple blockchains within individual queries, and local validation of blockchain data. These facets were only partially covered in previous research. The feasibility of implementing the language with its processing architecture has been positively evaluated using a prototype, despite the functional limitations mentioned in the previous discussion. Using the proposed approach of application-level interoperability, software can leverage multiple blockchains to establish a unified view on data while relying on verifiable transactions that are part of an open and permissionless infrastructure. In future research, these concepts can serve as a basis for addressing further integration aspects among blockchains, e.g. in terms of augmenting data storage distributed on multiple blockchains, and provide advanced integration methods towards enabling blockchains as decentralized application platforms. Acknowledgment This work is supported by the Swiss National Science Foundation project DomainSpecific Conceptual Modeling for Distributed Ledger Technologies [196889]. References Antonopoulos, A.M., Wood, G.: Mastering Ethereum: Building Smart Contracts and DApps. O’Reilly Media (2019) Bartoletti, M., Lande, S., Pompianu, L., Bracciali, A.: A general framework for blockchain analytics. In: 1st Workshop on Scalable and Resilient Infrastructures for Distributed Ledgers. pp. 1–6. SERIAL ’17, ACM, New York, NY, USA (2017). https://doi.org/10.1145/3152824.3152831 Belchior, R., Vasconcelos, A., Guerreiro, S., Correia, M.: A Survey on Blockchain Interoperability: Past, Present, and Future Trends. arXiv:2005.14282 [cs] (2021). https://doi.org/10.48550/arXiv.2005.14282 Belotti, M., Bozic, N., Pujolle, G., Secci, S.: A Vademecum on Blockchain Technologies: When, Which, and How. IEEE Communications Surveys & Tutorials 21(4), 3796–3838 (2019). https://doi.org/10.1109/COMST.2019.2928178 Bragagnolo, S., Rocha, H., Denker, M., Ducasse, S.: Ethereum query language. In: 1st International Workshop on Emerging Trends in Software Engineering for Blockchain. ACM (2018). https://doi.org/10.1145/3194113.3194114 Buterin, V.: Ethereum: A Next-Generation Smart Contract and Decentralized Application Platform. Tech. rep. (2014), https://ethereum.org/en/whitepaper Camozzi, G., Härer, F., Fill, H.G.: Multidimensional Analysis of Blockchain Data Using an ETL-based Approach. In: Wirtschaftsinformatik 2022 Proceedings (2022) Ethereum: Proof-of-stake (PoS) (2022), https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/ Garay, J., Kiayias, A., Leonardos, N.: The Bitcoin Backbone Protocol: Analysis and Applications. In: EUROCRYPT 2015. Springer (2015). https://doi.org/10.1007/978-3-662-46803-6 Gilad, Y., Hemo, R., Micali, S., Vlachos, G., Zeldovich, N.: Algorand: Scaling Byzantine Agreements for Cryptocurrencies. In: 26th Symposium on Operating Systems Principles. SOSP ’17, ACM (2017). https://doi.org/10.1145/3132747.3132757 Härer, F., Fill, H.G.: Decentralized attestation and distribution of information using blockchains and multi-protocol storage. IEEE Access 10, 18035–18054 (2022). https://doi.org/10.1109/ACCESS.2022.3150356 Hayward, A.: Solana Blames ‘Denial of Service Attack’ for Last Week’s Downtime (2021), Herlihy, M.: Atomic Cross-Chain Swaps. In: 2018 ACM Symposium on Principles of Distributed Computing. pp. 245–254. ACM, Egham United Kingdom (2018). https://doi.org/10.1145/3212734.3212736 Härer, F.: Towards interoperability of open and permissionless blockchains: A crosschain query language. In: 2022 IEEE International Conference on e-Business Engineering (ICEBE). pp. 190–197 (2022). https://doi.org/10.1109/ICEBE55470.2022.00041 Kiayias, A., Russell, A., David, B., Oliynykov, R.: Ouroboros: A Provably Secure Proof-of-Stake Blockchain Protocol. Tech. Rep. 889 (2016), https://eprint.iacr.org/2016/889 Ladleif, J., Weske, M.: A Unifying Model of Legal Smart Contracts. In: Conceptual Modeling. pp. 323–337. Springer International Publishing, Cham (2019). https: //doi.org/10.1007/978-3-030-33223-5_27 Liiv, I.: Exploration with Structured Query Language. In: Data Science Techniques for Cryptocurrency Blockchains. Behaviormetrics: Quantitative Approaches to Human Behavior, Springer (2021), http://doi.org/10.1007/978-981-16-2418-6_2 Narayanan, A., Clark, J.: Bitcoin’s academic pedigree. Communications of the ACM 60(12), 36–45 (2017). https://doi.org/10.1145/3132259 Olivé, A.: The Conceptual Schema of Ethereum. In: Dobbie, G., Frank, U., Kappel, G., Liddle, S.W., Mayr, H.C. (eds.) Conceptual Modeling. pp. 418– 428. Springer International Publishing, Cham (2020). Pillai, B., Biswas, K., Muthukkumarasamy, V.: Cross-chain interoperability among blockchain-based systems using transactions. The Knowledge Engineering Review 35 (2020). https://doi.org/10.1017/S0269888920000314 Rocket, T., Yin, M., Sekniqi, K., van Renesse, R., Sirer, E.G.: Scalable and Probabilistic Leaderless BFT Consensus through Metastability. arXiv:1906.08936 [cs] (2020). https://doi.org/10.48550/arXiv.1906.0893 S. Nakamoto: Bitcoin: A Peer-to-Peer Electronic Cash System. Tech. rep. (2008), https://bitcoin.org/bitcoin.pdf S. Nakamoto: Bitcoin - A software-based online payment system (2009), https://sourceforge.net/p/bitcoin/news/ Saad, M., Spaulding, J., Njilla, L., Kamhoua, C., Shetty, S., Nyang, D., Mohaisen, D.: Exploring the Attack Surface of Blockchain: A Comprehensive Survey. IEEE Communications Surveys & Tutorials 22(3) (2020). https://doi.org/10.1109/COMST.2020.2975999 Shadab, N., Houshmand, F., Lesani, M.: Cross-chain Transactions. In: 2020 IEEE International Conference on Blockchain and Cryptocurrency (ICBC). IEEE (2020). https://doi.org/10.1109/ICBC48266.2020.9169477 Shrivas, M.K., Dean, T.Y., Brunda, S.S.: The Disruptive Blockchain Security Threats and Threat Categorization. In: 2020 First International Conference on Power, Control and Computing Technologies (ICPC2T). IEEE, Raipur, India (2020). https://doi.org/10.1109/ICPC2T48082.2020.9071475 Weber, I., Staples, M.: Programmable money: Next-generation conditional payments using blockchain. In: 11th International Conference on Cloud Computing and Services Science - CLOSER,. pp. 7–14. INSTICC, SciTePress (2021). https://doi.org/10.5220/0010535800070014 Wood, G.: Ethereum: A secure decentralised generalised transaction ledger. Tech.rep., Ethereum (2022), https://ethereum.github.io/yellowpaper/paper.pdf Yakovenko, A.: Solana: A new architecture for a high performance blockchain v0.8.14. Tech. rep., Solana (2018), https://github.com/solana-labs/whitepaper/blob/master/solana-whitepaper-en.pdf Zakhary, V., Agrawal, D., El Abbadi, A.: Atomic commitment across blockchains. Proceedings of the VLDB Endowment 13(9), 1319–1331 (2020). https://doi.org/10.14778/3397230.3397231 Author: (1) Felix Härer[0000 −0002 −2768 −2342], Digitalization and Information Systems Group, University of Fribourg, Switzerland (felix.haerer@unifr.ch). This paper is available on arxiv under CC BY-NC-ND 4.0 DEED license. Table of Links Abstract and 1 Introduction Abstract and 1 Introduction 2 Background and Related Work and 2.1 From Bitcoin to Blockchains 2 Background and Related Work and 2.1 From Bitcoin to Blockchains 2.2 Open and Permissionless Blockchains 2.2 Open and Permissionless Blockchains 2.3 Interoperability Between Blockchains 2.3 Interoperability Between Blockchains 3 Cross-Chain Query Language and 3.1 Integrated Data Model 3 Cross-Chain Query Language and 3.1 Integrated Data Model 3.2 Grammar and Query Processing Architecture 3.2 Grammar and Query Processing Architecture 4 Evaluation of Implementation Feasibility and 4.1 Software and Hardware Configuration 4 Evaluation of Implementation Feasibility and 4.1 Software and Hardware Configuration 4.2 Query Processing 4.2 Query Processing 4.3 Discussion 4.3 Discussion 5 Conclusion and Outlook, Acknowledgment, and References 5 Conclusion and Outlook, Acknowledgment, and References 4.3 Discussion The prototype provides uniform data access to OPB, such as the retrieval of asset and data transfers across multiple blockchains. As per the defined grammar, data access is standardized, facilitating statements that involve one or more blockchains. For meaningful utilization of blockchain properties, it is essential to operate blockchain nodes locally, which can involve significant time and cost for initial synchronizations. The architecture of the data model follows a data integration approach, where data conforming to well-known OPB can be stored by populating pertinent classes. In contrast, merely relying on multiple individual data models would fail to address the issue at hand. Due to the generic and unifying approach, the prototype in its current form has limited support for advanced concepts specific to individual OPB. For instance, calculating transaction fees involving additional utility tokens falls outside the scope of this model. Functionality-wise, limitations concern the processing of queries with filters. Currently, the prototype is constrained to the sequential application of filters with equality comparisons. In addition, the processing is limited to the classes and attributes present in the data model. In future development, further blockchain-specific processing logic and attributes could be added to the architecture and the data model, respectively. At this point, the prototype demonstrates the general feasibility of a domain-specific language that supports multiple blockchains. Regarding atomicity, it is supported on a technical level for query transactions within the data model, however, the API-based access approach does not allow for atomicity guarantees that depend on the software node implementations of different blockchains. Oftentimes, APIs do not provide specific atomicity or strong consistency guarantees and instead rely on eventual consistency. For this reason, access through APIs limits the possibility of strong guarantees for the prototype. 5 Conclusion and Outlook This paper presents a cross-chain query language grammar, data model, and processing architecture aimed at facilitating uniform data access across multiple blockchains. The approach enables homogeneous data access, query standardization, addressing multiple blockchains within individual queries, and local validation of blockchain data. These facets were only partially covered in previous research. The feasibility of implementing the language with its processing architecture has been positively evaluated using a prototype, despite the functional limitations mentioned in the previous discussion. Using the proposed approach of application-level interoperability, software can leverage multiple blockchains to establish a unified view on data while relying on verifiable transactions that are part of an open and permissionless infrastructure. In future research, these concepts can serve as a basis for addressing further integration aspects among blockchains, e.g. in terms of augmenting data storage distributed on multiple blockchains, and provide advanced integration methods towards enabling blockchains as decentralized application platforms. Acknowledgment This work is supported by the Swiss National Science Foundation project DomainSpecific Conceptual Modeling for Distributed Ledger Technologies [196889]. References Antonopoulos, A.M., Wood, G.: Mastering Ethereum: Building Smart Contracts and DApps. O’Reilly Media (2019) Bartoletti, M., Lande, S., Pompianu, L., Bracciali, A.: A general framework for blockchain analytics. In: 1st Workshop on Scalable and Resilient Infrastructures for Distributed Ledgers. pp. 1–6. SERIAL ’17, ACM, New York, NY, USA (2017). https://doi.org/10.1145/3152824.3152831 Belchior, R., Vasconcelos, A., Guerreiro, S., Correia, M.: A Survey on Blockchain Interoperability: Past, Present, and Future Trends. arXiv:2005.14282 [cs] (2021). https://doi.org/10.48550/arXiv.2005.14282 Belotti, M., Bozic, N., Pujolle, G., Secci, S.: A Vademecum on Blockchain Technologies: When, Which, and How. IEEE Communications Surveys & Tutorials 21(4), 3796–3838 (2019). https://doi.org/10.1109/COMST.2019.2928178 Bragagnolo, S., Rocha, H., Denker, M., Ducasse, S.: Ethereum query language. In: 1st International Workshop on Emerging Trends in Software Engineering for Blockchain. ACM (2018). https://doi.org/10.1145/3194113.3194114 Buterin, V.: Ethereum: A Next-Generation Smart Contract and Decentralized Application Platform. Tech. rep. (2014), https://ethereum.org/en/whitepaper Camozzi, G., Härer, F., Fill, H.G.: Multidimensional Analysis of Blockchain Data Using an ETL-based Approach. In: Wirtschaftsinformatik 2022 Proceedings (2022) Ethereum: Proof-of-stake (PoS) (2022), https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/ Garay, J., Kiayias, A., Leonardos, N.: The Bitcoin Backbone Protocol: Analysis and Applications. In: EUROCRYPT 2015. Springer (2015). https://doi.org/10.1007/978-3-662-46803-6 Gilad, Y., Hemo, R., Micali, S., Vlachos, G., Zeldovich, N.: Algorand: Scaling Byzantine Agreements for Cryptocurrencies. In: 26th Symposium on Operating Systems Principles. SOSP ’17, ACM (2017). https://doi.org/10.1145/3132747.3132757 Härer, F., Fill, H.G.: Decentralized attestation and distribution of information using blockchains and multi-protocol storage. IEEE Access 10, 18035–18054 (2022). https://doi.org/10.1109/ACCESS.2022.3150356 Hayward, A.: Solana Blames ‘Denial of Service Attack’ for Last Week’s Downtime (2021), Herlihy, M.: Atomic Cross-Chain Swaps. In: 2018 ACM Symposium on Principles of Distributed Computing. pp. 245–254. ACM, Egham United Kingdom (2018). https://doi.org/10.1145/3212734.3212736 Härer, F.: Towards interoperability of open and permissionless blockchains: A crosschain query language. In: 2022 IEEE International Conference on e-Business Engineering (ICEBE). pp. 190–197 (2022). https://doi.org/10.1109/ICEBE55470.2022.00041 Kiayias, A., Russell, A., David, B., Oliynykov, R.: Ouroboros: A Provably Secure Proof-of-Stake Blockchain Protocol. Tech. Rep. 889 (2016), https://eprint.iacr.org/2016/889 Ladleif, J., Weske, M.: A Unifying Model of Legal Smart Contracts. In: Conceptual Modeling. pp. 323–337. Springer International Publishing, Cham (2019). https: //doi.org/10.1007/978-3-030-33223-5_27 Liiv, I.: Exploration with Structured Query Language. In: Data Science Techniques for Cryptocurrency Blockchains. Behaviormetrics: Quantitative Approaches to Human Behavior, Springer (2021), http://doi.org/10.1007/978-981-16-2418-6_2 Narayanan, A., Clark, J.: Bitcoin’s academic pedigree. Communications of the ACM 60(12), 36–45 (2017). https://doi.org/10.1145/3132259 Olivé, A.: The Conceptual Schema of Ethereum. In: Dobbie, G., Frank, U., Kappel, G., Liddle, S.W., Mayr, H.C. (eds.) Conceptual Modeling. pp. 418– 428. Springer International Publishing, Cham (2020). Pillai, B., Biswas, K., Muthukkumarasamy, V.: Cross-chain interoperability among blockchain-based systems using transactions. The Knowledge Engineering Review 35 (2020). https://doi.org/10.1017/S0269888920000314 Rocket, T., Yin, M., Sekniqi, K., van Renesse, R., Sirer, E.G.: Scalable and Probabilistic Leaderless BFT Consensus through Metastability. arXiv:1906.08936 [cs] (2020). https://doi.org/10.48550/arXiv.1906.0893 S. Nakamoto: Bitcoin: A Peer-to-Peer Electronic Cash System. Tech. rep. (2008), https://bitcoin.org/bitcoin.pdf S. Nakamoto: Bitcoin - A software-based online payment system (2009), https://sourceforge.net/p/bitcoin/news/ Saad, M., Spaulding, J., Njilla, L., Kamhoua, C., Shetty, S., Nyang, D., Mohaisen, D.: Exploring the Attack Surface of Blockchain: A Comprehensive Survey. IEEE Communications Surveys & Tutorials 22(3) (2020). https://doi.org/10.1109/COMST.2020.2975999 Shadab, N., Houshmand, F., Lesani, M.: Cross-chain Transactions. In: 2020 IEEE International Conference on Blockchain and Cryptocurrency (ICBC). IEEE (2020). https://doi.org/10.1109/ICBC48266.2020.9169477 Shrivas, M.K., Dean, T.Y., Brunda, S.S.: The Disruptive Blockchain Security Threats and Threat Categorization. In: 2020 First International Conference on Power, Control and Computing Technologies (ICPC2T). IEEE, Raipur, India (2020). https://doi.org/10.1109/ICPC2T48082.2020.9071475 Weber, I., Staples, M.: Programmable money: Next-generation conditional payments using blockchain. In: 11th International Conference on Cloud Computing and Services Science - CLOSER,. pp. 7–14. INSTICC, SciTePress (2021). https://doi.org/10.5220/0010535800070014 Wood, G.: Ethereum: A secure decentralised generalised transaction ledger. Tech.rep., Ethereum (2022), https://ethereum.github.io/yellowpaper/paper.pdf Yakovenko, A.: Solana: A new architecture for a high performance blockchain v0.8.14. Tech. rep., Solana (2018), https://github.com/solana-labs/whitepaper/blob/master/solana-whitepaper-en.pdf Zakhary, V., Agrawal, D., El Abbadi, A.: Atomic commitment across blockchains. Proceedings of the VLDB Endowment 13(9), 1319–1331 (2020). https://doi.org/10.14778/3397230.3397231 Antonopoulos, A.M., Wood, G.: Mastering Ethereum: Building Smart Contracts and DApps. O’Reilly Media (2019) Antonopoulos, A.M., Wood, G.: Mastering Ethereum: Building Smart Contracts and DApps. O’Reilly Media (2019) Bartoletti, M., Lande, S., Pompianu, L., Bracciali, A.: A general framework for blockchain analytics. In: 1st Workshop on Scalable and Resilient Infrastructures for Distributed Ledgers. pp. 1–6. SERIAL ’17, ACM, New York, NY, USA (2017). https://doi.org/10.1145/3152824.3152831 Bartoletti, M., Lande, S., Pompianu, L., Bracciali, A.: A general framework for blockchain analytics. In: 1st Workshop on Scalable and Resilient Infrastructures for Distributed Ledgers. pp. 1–6. SERIAL ’17, ACM, New York, NY, USA (2017). https://doi.org/10.1145/3152824.3152831 https://doi.org/10.1145/3152824.3152831 Belchior, R., Vasconcelos, A., Guerreiro, S., Correia, M.: A Survey on Blockchain Interoperability: Past, Present, and Future Trends. arXiv:2005.14282 [cs] (2021). https://doi.org/10.48550/arXiv.2005.14282 Belchior, R., Vasconcelos, A., Guerreiro, S., Correia, M.: A Survey on Blockchain Interoperability: Past, Present, and Future Trends. arXiv:2005.14282 [cs] (2021). https://doi.org/10.48550/arXiv.2005.14282 https://doi.org/10.48550/arXiv.2005.14282 Belotti, M., Bozic, N., Pujolle, G., Secci, S.: A Vademecum on Blockchain Technologies: When, Which, and How. IEEE Communications Surveys & Tutorials 21(4), 3796–3838 (2019). https://doi.org/10.1109/COMST.2019.2928178 Belotti, M., Bozic, N., Pujolle, G., Secci, S.: A Vademecum on Blockchain Technologies: When, Which, and How. IEEE Communications Surveys & Tutorials 21(4), 3796–3838 (2019). https://doi.org/10.1109/COMST.2019.2928178 https://doi.org/10.1109/COMST.2019.2928178 Bragagnolo, S., Rocha, H., Denker, M., Ducasse, S.: Ethereum query language. In: 1st International Workshop on Emerging Trends in Software Engineering for Blockchain. ACM (2018). https://doi.org/10.1145/3194113.3194114 Bragagnolo, S., Rocha, H., Denker, M., Ducasse, S.: Ethereum query language. In: 1st International Workshop on Emerging Trends in Software Engineering for Blockchain. ACM (2018). https://doi.org/10.1145/3194113.3194114 https://doi.org/10.1145/3194113.3194114 Buterin, V.: Ethereum: A Next-Generation Smart Contract and Decentralized Application Platform. Tech. rep. (2014), https://ethereum.org/en/whitepaper Buterin, V.: Ethereum: A Next-Generation Smart Contract and Decentralized Application Platform. Tech. rep. (2014), https://ethereum.org/en/whitepaper https://ethereum.org/en/whitepaper Camozzi, G., Härer, F., Fill, H.G.: Multidimensional Analysis of Blockchain Data Using an ETL-based Approach. In: Wirtschaftsinformatik 2022 Proceedings (2022) Camozzi, G., Härer, F., Fill, H.G.: Multidimensional Analysis of Blockchain Data Using an ETL-based Approach. In: Wirtschaftsinformatik 2022 Proceedings (2022) Ethereum: Proof-of-stake (PoS) (2022), https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/ Ethereum: Proof-of-stake (PoS) (2022), https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/ https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/ Garay, J., Kiayias, A., Leonardos, N.: The Bitcoin Backbone Protocol: Analysis and Applications. In: EUROCRYPT 2015. Springer (2015). https://doi.org/10.1007/978-3-662-46803-6 Garay, J., Kiayias, A., Leonardos, N.: The Bitcoin Backbone Protocol: Analysis and Applications. In: EUROCRYPT 2015. Springer (2015). https://doi.org/10.1007/978-3-662-46803-6 https://doi.org/10.1007/978-3-662-46803-6 Gilad, Y., Hemo, R., Micali, S., Vlachos, G., Zeldovich, N.: Algorand: Scaling Byzantine Agreements for Cryptocurrencies. In: 26th Symposium on Operating Systems Principles. SOSP ’17, ACM (2017). https://doi.org/10.1145/3132747.3132757 Gilad, Y., Hemo, R., Micali, S., Vlachos, G., Zeldovich, N.: Algorand: Scaling Byzantine Agreements for Cryptocurrencies. In: 26th Symposium on Operating Systems Principles. SOSP ’17, ACM (2017). https://doi.org/10.1145/3132747.3132757 https://doi.org/10.1145/3132747.3132757 Härer, F., Fill, H.G.: Decentralized attestation and distribution of information using blockchains and multi-protocol storage. IEEE Access 10, 18035–18054 (2022). https://doi.org/10.1109/ACCESS.2022.3150356 Härer, F., Fill, H.G.: Decentralized attestation and distribution of information using blockchains and multi-protocol storage. IEEE Access 10, 18035–18054 (2022). https://doi.org/10.1109/ACCESS.2022.3150356 https://doi.org/10.1109/ACCESS.2022.3150356 Hayward, A.: Solana Blames ‘Denial of Service Attack’ for Last Week’s Downtime (2021), Hayward, A.: Solana Blames ‘Denial of Service Attack’ for Last Week’s Downtime (2021), Herlihy, M.: Atomic Cross-Chain Swaps. In: 2018 ACM Symposium on Principles of Distributed Computing. pp. 245–254. ACM, Egham United Kingdom (2018). https://doi.org/10.1145/3212734.3212736 Herlihy, M.: Atomic Cross-Chain Swaps. In: 2018 ACM Symposium on Principles of Distributed Computing. pp. 245–254. ACM, Egham United Kingdom (2018). https://doi.org/10.1145/3212734.3212736 https://doi.org/10.1145/3212734.3212736 Härer, F.: Towards interoperability of open and permissionless blockchains: A crosschain query language. In: 2022 IEEE International Conference on e-Business Engineering (ICEBE). pp. 190–197 (2022). https://doi.org/10.1109/ICEBE55470.2022.00041 Härer, F.: Towards interoperability of open and permissionless blockchains: A crosschain query language. In: 2022 IEEE International Conference on e-Business Engineering (ICEBE). pp. 190–197 (2022). https://doi.org/10.1109/ICEBE55470.2022.00041 https://doi.org/10.1109/ICEBE55470.2022.00041 Kiayias, A., Russell, A., David, B., Oliynykov, R.: Ouroboros: A Provably Secure Proof-of-Stake Blockchain Protocol. Tech. Rep. 889 (2016), https://eprint.iacr.org/2016/889 Kiayias, A., Russell, A., David, B., Oliynykov, R.: Ouroboros: A Provably Secure Proof-of-Stake Blockchain Protocol. Tech. Rep. 889 (2016), https://eprint.iacr.org/2016/889 https://eprint.iacr.org/2016/889 Ladleif, J., Weske, M.: A Unifying Model of Legal Smart Contracts. In: Conceptual Modeling. pp. 323–337. 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Author: Author: (1) Felix Härer[0000 −0002 −2768 −2342], Digitalization and Information Systems Group, University of Fribourg, Switzerland (felix.haerer@unifr.ch). This paper is available on arxiv under CC BY-NC-ND 4.0 DEED license. This paper is available on arxiv under CC BY-NC-ND 4.0 DEED license. available on arxiv available on arxiv