Assessing trust in the long-term protection of documents

Digital archives rely on trusted parties, such as certification authorities, to ensure authenticity, integrity and proof of existence protection for documents. In this paper, we analyse the trust assumptions that a verifier has to make in order to trust in the protection of a document. We show that trust fades out in the long term due to the ever-growing number of trusted parties. Despite such a dire prospect, current technologies such as X.509 PKI do not assess trust, thereby leaving verifiers in the dark. We present a certification scheme for documents that provides verifiers with a better assessment of trust than in X.509 PKI. In the proposed scheme, trusted parties are rated based on the correctness of their performance. From the ratings, verifiers can assess quantitatively the trust in the trusted parties for the short term, and in the protection of documents for the long term. The proposed scheme encourages trusted parties to work properly.