Biblio

Many blockchain transactions require blockchain-external data sources to provide data. Oracle systems have been proposed as a link between blockchains and blockchain-external resources. However, these Oracle systems vary greatly in assumptions and applicability and each system addresses the challenge of data on-chaining partly. We argue that Data On-chaining must be done in a trustworthy manner and, as a first contribution, define a set of key requirements for Trustworthy Data On-chaining. Further, we provide an in-depth assessment and comparison of state-of-the-art Oracle systems with regards to these requirements. This differentiation pinpoints the need for a uniform understanding of and directions for future research on Trustworthy Data On-chaining.

Cloud systems offer a diversity of security mechanisms with potentially complex configuration options. So far, security engineering has focused on achievable security levels, but not on the costs associated with a specific security mechanism and its configuration. Through a series of experiments with a variety of cloud datastores conducted over the last years, we gained substantial knowledge on how one desired quality like security can have a significant impact on other system qualities like performance. In this paper, we report on select findings related to security-performance trade-offs for three prominent cloud datastores, focusing on data in transit encryption, and propose a simple, structured approach for making trade-off decisions based on factual evidence gained through experimentation. Our approach allows to rationally reason about security trade-offs.