I wrote about this on June 7 at http://eogn.com/20180607a. Now an article by Alex Green in The National Archives Blog provides more information. Alex Green writes:
“Blockchain is a distributed ledger technology which is both tamper-resistant and decentralised. The ARCHANGEL project is creating a prototype using this technology which aims to enable archives to generate and register hashes of documents (similar to unique digital signatures) into a permissioned blockchain (in other words, one which can only be added to by authorised organisations). Where the record has been legitimately changed, hashes of the content, alongside hashes of the code used to make the change, can also be registered on the blockchain. This would mean that whenever a digital record is modified, an audit trail is created and we are able to know exactly how a document has been edited.
“Our approach will result in the creation of many copies of a persistent and unchangeable record of the state of a document. This record will be verifiable using the same cryptographic algorithms, many years into the future.
“As this approach matures, we hope that the ledger would be maintained collaboratively by distributing it across many participating archives both in the UK and internationally, as a promise that no individual institution could attempt to rewrite history. This technology could transform the sustainability of digital public archives, enabling archives to share the stewardship of the records and, by sharing, guarantee the integrity of the records they hold.”
You can read a lot more in The National Archives Blog at https://blog.nationalarchives.gov.uk/blog/trustworthy-technology-future-digital-archives.