it – Information Technology 2018; aop Uwe Roth* and Theophane Ngne Djoua Message exchange on base of a blockchain-based layered architecture https://doi.org/10.1515/itit-2017-0037 Received December 1, 2017; revised April 18, 2018; accepted Octo- ber 1, 2018 Abstract: In this article, we propose an architecture that allows to exchange messages or data via a blockchain so- lution, while keeping the business process independent from the concrete blockchain. The project is the conse- quence of a need to have fast development of a blockchain based proof of concept that shows the feasibility of a busi- ness process, while knowing that in a future step the un- derlying blockchain solution has to be replaced for reasons of licensing or maximal data throughput. This is done by providing an architecture on base of layers, similar to the OSI-model, and encapsulates the used blockchain within a wrapper layer that covers all blockchain specifc proper- ties and only provides a transparent view on the reading or writing from and to the blockchain. The higher layers re- implement point-to-point communication and introduce confdentiality by the use of encryption techniques. The architecture has been tested and proven by implement- ing two diferent blockchain solutions that are shielded by specifc wrapper layer implementations. This wrapper layer is responsible for the fragmentation of the sent data and their encapsulation into the concrete blockchain solu- tion. The reconstruction of the data takes care of the data fragments being sent potentially out of order or being in- complete. A payload layer is introduced to provide point- to-point communication and to embed the main message inside a message structure. In collaboration with under- lying layer it identifes for which message one is not the addressee and allow the underling layer to stop collect- ing unnecessary data. A crypto-layer fnally provides ways of encrypting messages for one or many recipients. Hav- ing fxed layers not only allows to replace the underlying blockchain solution but also to extend or replace the other layers in case new security features or optimized protocols need to embedded. The proposed solution does not allow *Corresponding author: Uwe Roth, Luxembourg Institute of Science and Technology, LIST, ITIS Department, Security and Privacy Group, 5, avenue des Hauts-Fourneaux, L-4362 Esch/Alzette, Luxembourg, e-mail: uwe.roth@list.lu, ORCID: http://orcid.org/0000-0003-0762-4345 Theophane Ngne Djoua, T-Systems International GmbH, Cyberdefence Opereation Center, Bonn, Germany, e-mail: theophane.ngne-djoua@t-systems.com to use specifc features like smart contracts and only pro- vides undeniable tamper-proofed existence of a sent mes- sage. Keywords: Blockchain, OSI-model, layered network archi- tecture, distributed database, message exchange ACM CCS: CCS, Networks, Network protocols, Application layer protocols 1 Introduction Blockchain technology provides some nice properties that makes it interesting for developing applications that de- pend on a decentralized database setting of equal entities and equal rights to irrefutable write to that database. A variety of blockchain solutions have already be de- veloped, all with diferent level of maturity and technical properties. The building of complex business processes on top of these solutions might be at the current time risky since none of these solutions has been fully accepted as a standard. In the future, some solution might be discontin- ued or heavily change their architecture which could lead to a need to switch the technology and to re-implement parts of the existing software. Another problem is the use of blockchain solutions inside patented products, even in case of open source software. The main problem is, that the authors of the blockchain software in some case will have the right to publish the patented solution without infringing the patent. During the proof of concept phase this might not necessary be of relevance and only fast coding is of inter- est. But later during the development of the prototype and minimal vial product, the blockchain needs to be replaced by a solution that has either a more liberal license or which is licensed on base of payments or contracts. In both cases, the building of applications on base of blockchain solutions is demanded, but with the possibil- ity to replace that foundation later without afecting the application. This type of fexibility is currently not given. As a consequence, a layered architecture is proposed in the article, that is inspired by the OSI model [11] as it is used to structure communication without considering the under- lying technology. Brought to you by | La Trobe University Authenticated Download Date | 10/21/18 8:41 PM