Developing IntegrityCatalog, a software system for managing integrity-related metadata in digital repositories

摘要

Digital repositories must periodically check the integrity of stored objects to assure users of their correctness. Prior solutions calculate integrity metadata and require the repository to store it alongside the actual data objects. To safeguard and detect damage to this metadata, prior solutions rely on widely visible media (unaffiliated third parties) to store and provide back digests of the metadata to verify it is intact. However, they do not address recovery of the integrity metadata in case of damage or adversarial attack. We introduce IntegrityCatalog, a novel software system that can be integrated into any digital repository. It collects all integrity-related metadata in a single component and treats them as first class objects, managing both their integrity and their preservation. We introduce a treap-based persistent authenticated dictionary managing arbitrary length key/value pairs, which we use to store all integrity metadata, accessible simply by object name. Additionally, IntegrityCatalog is a distributed system that includes a network protocol that manages both corruption detection and preservation of this metadata, using administrator-selected network peers with 2 possible roles. Verifiers store and offer attestations on digests and have minimal storage requirements, while preservers efficiently synchronize a complete copy of the catalog to assist in recovery in case of a detected catalog compromise on the local system. We present our approach in developing the prototype implementation, measure its performance experimentally, and demonstrate its effectiveness in real-world situations. We believe the implementation techniques of our open-source IntegrityCatalog will be useful in the construction of next-generation digital repositories.