Provenance information documents the history of an object and can be used for assessing its quality, reliability, and trustworthiness. This thesis aims to design and implement a web service architecture to support integrity and non-repudiation of provenance information in a multi-organizational environment. In particular, the student will: 1) get familiar with the current W3C PROV standard for provenance information representation and additional specifications for multi-organizational provenance (the Common Provenance Model); 2) design and implement a service architecture for storing and retrieving provenance information according to the specifications, with a requirement to support provenance integrity and non-repudiation of origin of provenance in a multi-institutional environment; 3) demonstrate how integrity and non-repudiation of provenance can be verified using the implemented services. The service architecture will be based on trusted parties who witness and testify the origin of provenance. The resulting architecture will be based on preliminary work on non-repudiable provenance information for Clinical Decision Support Systems, where a generic non-repudiation policy was formulated. The text part of the thesis will describe how specific points of the non-repudiation policy were addressed in the resulting architecture.