Certify your digital assets on the blockchain

Documentary certification

Alain Broustail, Director of Blockchain Activities at Coexya

Documentary certification. What is it, what is it for and how does it work? Ever since man first learned to write, the question of the authenticity of a document has arisen. I'm a soldier, does the order I receive really come from the general? Was this document signed by the king himself? Is this the latest version of the will? Am I not making a mistake? Even in everyday life, today, every day, we have the subject. You register your children for school, for the crèche, they ask you for proof of address, you send a PDF file issued by your energy company. Is it an original or have you defrauded them? They ask you for a certificate of civil liability insurance as a contractor. You could be forging it. You're a musician, you create a piece of music, you're a photographer, you take a photo, you post it online. The next day, you see your photo, your piece of music on every website, someone has used it without asking your permission, without paying you royalties. Is there any way you can prove that you are the author of this document? There are many examples.
So, to verify the authenticity of a document, man has invented many things over time. They invented the signature, so you put on a nice signature, and the more complex and difficult it is to forge, the more certain you are. We invented the seal, the candle, the seal, the wax. Not only can you prove that you are the author of a letter, but also that it has not been opened. Or more recently, you know, the company stamp, which is still used quite often. Witnesses are also used, so you get married in front of a witness at the town hall. You'll ask a notary to witness that you've drawn up a will, or you'll call in a bailiff to certify that you're the author of a document. There are lots of ways of doing this, you can work on the medium. If you look at this banknote, for example, you could forge it, but inside the banknote, on the paper itself, there are filigrees and codes, and it's very hard to forge banknotes. Just like an identity card, there are lots of codes hidden inside an identity card, and it's very hard to make a fake identity card.
So, on a day-to-day basis, we don't necessarily know how to produce this kind of thing, but we have invented other technologies: barcodes, QR codes, 2D-Docs, where we take a normal piece of paper and add anti-fraud information inside. Another problem we have to deal with is time stamping, i.e. how old the document is. For a long time, my only solution was to write it down on paper and have a witness confirm it. Then we invented postal services, in particular the postmark. So we have a new witness, but it's not a physical witness, it's an entity that says, yes, I was there, it was such and such a date, such and such a time. So the time arrived gradually. The arrival of the digital economy, particularly over the last 20 years, has turned this whole ecosystem of trusted third parties upside down. You can no longer physically affix a seal or sign a document, you have to work with digital technology.
So we invented new technologies, called asymmetric cryptography, called certificates, so all these are things that exist today on the Internet, which allow us to check that we are communicating with our bank account and not with a hacker. We invented the principle of hashing a document. Without going into too much detail, this is what enables us to check that a document has not been modified from a previous version. So all these elements add up. So overall, what we've done is change the old witnesses - the mayor, the notary or the post office - with new witnesses who will be time-stamping service providers, electronic signature service providers or certificate issuers. Another innovation has appeared more recently that is of particular interest to us for digital evidence: the public blockchain. Remember that a blockchain is a database synchronised between multiple participants, it is decentralised and everyone will have a copy.
So we have thousands of participants who we will call miners and when I insert information and why not the hash of a document, everyone will be able to see this hash, will agree on the time and date when this hash arrived, and there will be information on the sender. So I'll be able to prove that the file came from me, that I'm the original author, and it doesn't have to be just a PDF, it could be a piece of music, it could be an Excel file, it could be a ZIP file, I'll generate proof of anteriority and be able to prove that it's an original, or that I'm the author, or that the date has been respected. I have replaced the traditional trusted third parties - notaries, the post office or the issuer of certificates to electronic signature providers on the Internet - with a new type of trusted third party witness, which is the public blockchain. It is in fact a technological protocol, code, software, and then miners, thousands of miners who a priori have no reason to be impartial. Let's say goodbye to the old and welcome to the public blockchain, which in my view is perhaps the best documentary certification solution currently available on the market.