Notarization on the Dune Network Blockchain

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Dune Network

5 min readJul 9, 2020

Blockchains provide immutable history as one of their first features: nothing written in a block more than a few hours ago can be tampered by anybody. Notarization is an immediate application of such a feature: if you want to prove that you owned a document at a given time, you can just use this feature by storing a fingerprint (hash) of the document in a block (documents are usually too big to be stored, while the fingerprint is only a few bytes and provides cryptographic equivalence). Later, you can prove that you issued the transaction at the given time, showing that you had the document.

For Dune Network, we decided to make it easy to benefit from this feature: we provide two ways to notarize documents on the chain, one for basic users, and another one with higher-throughput for companies.

Basic Notarization using Metal

Metal is a browser extension for Dune Network. It allows you to safely interact with DApps, giving them the ability to create transactions (that Metal asks you to confirm) without compromising your secret key.

Once you have configured Metal with your account information, it appears in the top-right corner of your web browser. Clicking on it will open a small window like this one:

If you want to notarize a document, click on the “Expand” button (the one in the middle), it should open a web page like this one:

At this point, check that the selected network is “Mainnet” in the dropdown menu in the top right corner.

Then, you can see the “Notarize” tab among the possible operations that Metal proposes. Click on it to go to that tab:

Let’s click on “Browse” to pick up the file we want to notarize. We can also add a small comment, for example my email address:

Click on the “Notarize” button: Metal opens a popup to display the operation before asking you for confirmation. If you are using a hardware wallet, Metal will interact with it before and after this step, don’t forget to plug it and validate every step.

Confirm, and Metal will display the operation being confirmed:

The operation also appears in the Transfer tab:

Let’s click on the operation link to see what happened: we are redirected on Dunscan to see the operation internals.

If we have a closer look at the parameters:

We can compare these parameters with the sha256hash of the file:

It matches, we have a proof that the file content was associated with our address in the blockchain !

Checking Notarized Files

Metal is nice for notarizing files, but we may also want to check whether a particular file was notarized in the past. For that, notarize.dune.network provides a much better interface:

When we arrive on the dapp, it connects with Metal to find out our account (you must allow the connection if prompted).

We see that we can also notarize a file with the bottom-right button “New Notarization”:

You can try to notarize a new document, it will appear both in Metal and on the page (after a reload).

But more interesting is the “Check” button. It opens the following popup:

Let’s select the file that we previously notarized:

and click on “Check”:

It shows that the file was notarized, and when, as well as a link on Dunscan to the operation proving that the file was notarized be this account!

Finally, here is a graph explaining how it works, as a cooperation between the Notarize dapp, the Metal browser extension, the Dune Network blockchain and the Dunscan block explorer:

Handwritten schema of Dune Notarize (France, 2020 AC)

Automated Notarization

Many companies are also interested in notarizing some of their data. Yet, if you have much data to notarize, or if your data has to be notarized frequently, you don’t want to do it manually. Instead, you want a service with which your applications can interact easily, in order to send fingerprints to be notarized, and to then later request proofs of notarization.

Origin Labs has developed exactly that, a service for Dune Network that can be tuned to your notarization needs, with a high-throughput: instead of using one transaction on the blockchain for each document, all the documents arriving in a period of time are notarized together in a single operation, using a simple mechanism called Merkle Trees: