Digital Archives Relying on Blockchain: Overcoming the Limitations of Data Immutability

Archives, both analogue and digital, are primarily concerned with preserving records as originals. Because of this, immutable data as used in a blockchain data structure seem a logical choice when designing such systems. At the same time, archives maintain records which may need to change over the long term. It is a requirement of archival preservation to be able to update records’ metadata in order not only to guarantee authenticity after digital preservation actions but also to ensure that relationships to other records, which might be created after an original record has entered the archive (and has been registered in a blockchain), can be maintained. The need to maintain an archival bond, which represents a network of relationships between aggregation of records, i.e., the relationship connecting previous and subsequent records belonging to the same activity, is a prime example of this requirement. This paper explores realisation of the archival bond in the context of blockchain-based archival system by proposing a supporting database system which enables metadata to be changed as required but also significantly simplifies searching compared to searching on-chain information, while keeping the immutability characteristic of blockchain.