## 6 Discussion  
It is widely accepted that trust and compliance in cloud applications is a wide and extensively researched area due to its significance. Throughout this research effort, the focusprimarily remains on compliance issus. Specifically, the focus was on the automation and decentralized provability of configuration changes, which could benefit a dispute. While blockchain is a promising technology, it faces numerous challenges, including scalability, privacy leakage, governance, and compliance with regulations [2; 56]. Data sharing is a challenge in cloud applications, since users lack a mechanism to regulate data. This article introduces a novel architecture to configure cloud applications. The proposed architecture is based on data encryption and digital signatures to guarantee data confidentiality and integrity. This study presents a blockchain-based protocol that can automatically negotiate a key between multiple parties. The negotiated multiparty key is used to store configurations via a smart contract. The cloud application is notified of changes in the configuration via a monitoring mechanism. Consequently, the configuration changes are uploaded onto the cloud application and implemented using a cloud-side script. Once the configuration has been successfully implemented, the cloud-side script triggers a snapshot of the cloud instance loaded from external storage onto the cloud instance. On the cloud instance end, the cryptographic hash value for the snapshot is computed and, subsequently, written onto the blockchain. These steps occur automatically, and require the user to provide an encrypted configuration with the negotiated key. The main objective of this study was to present a decentralized reference architecture for the automated, transparent, and notarized configuration of cloud applications. The adopted approach can be used to configure cloud applications in a non-reputable way. Once the cloud management script has detected a successful implementation, it triggers a backup of the cloud instance, and the computed hash value forms a unique fingerprint of the cloud instance. If a dispute arises between two parties, the stored and created snapshot can be consulted, and its hash value can be compared with the hash value stored in the blockchain. A legal dispute can be conducted based on this snapshot. Neither of the parties can deny that the snapshot is not the actual configuration of the cloud application. However, the qualitative evaluation of the proposed architecture also has certain limitations. Creating a snapshot can be a bottleneck for the application. The prototype presented here needs almost four minutes to set the configuration through a smart contract to confirm the configuration by saving the snapshot hash value. The main reason for this was the hash value generation of a 30 GiB snapshot. Therefore, operating the cloud instance with the smallest possible hard-disk space is recommended. In addition, experts primarily see the architecture in the environment of SMEs and their cloud applications. The implementation of large cloud applications can be very complex. However, this was not generally ruled out by the experts. In the final analysis, experts considered the approach to be conceivable and feasible in the software-as-a-service area, as they saw the greatest need for a compliance solution there. In addition to technical benefits, such as the tamperproof properties of blockchain entries, the application for configuring applications also offers economic advantages. Cloud configurations are set using smart contracts. By linking transaction costs to the smart contract function, it is possible to transparently indicate upcoming costs for configuration changes and prevent unexpected costs based on compliance adjustments. Furthermore, the payment function of smart contracts can also be used to compensate for other services, such as the cost of storing snapshots, or to pay for additional cloud resources.