We present a “content integrity service” for long- lived digital documents, especially for objects stored in digital repositories. The goal of the service is to demonstrate that information in the repository is authentic and has not been unintentionally or maliciously altered, even after its bit representation in the repository has undergone one or more transformations. We describe our design for an efficient, secure service that achieves this, and our implementations of two prototypes of such a service that we developed, most recently for DSpace. Our solution relies on one-way hashing and digital time- stamping procedures. Our service applies not only to transformations to archival content such as format changes, but also to the introduction of new cryptographic primitives, such as the new one-way hash function family that will be chosen by NIST in the competition that was recently announced [10]. In the face of recent attacks on hash functions, this feature is absolutely necessary to the design of an integrity- preserving system that is meant to endure for decades.
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