Durable medium – Description of S3DOC

The three diamonds in the S3DOC logo symbolise the three most important features of the system: durability, stability and safety.

The S3DOC system has many other interesting features. All of them were achieved through the use of innovative Blockchain and DHT technologies.


Durable medium

The main purpose for which the S3DOC system was created is to ensure the permanence of the documents entered into the system.

How is durability understood?

In our case, we are sure that once a document is entered, it will not be modified and cannot be removed. It will be available to users unchanged throughout the life cycle of the S3DOC system.

Durability and invariability is guaranteed by cryptographic mechanisms such as digital fingerprint and Merkle tree.

These features mean that S3DOC can be considered as a durable medium in compliance with EU directives.


The S3DOC system audit for durable media has just been completed. The audit was conducted by a team of scientists from the System Research Institute of the Polish Academy of Sciences.

The result of the audit is positive, which means that the S3DOC system complies with all the features of a durable medium taking into account the definitions of the European Union and the Polish Office of Competition and Consumer Protection.

Therefore, the S3DOC system now has the opinion of an external institution that it complies with all the features of a durable medium.

After analysing the features of a durable medium, the architecture of the entire solution was also very well evaluated.

The opinion of System Research Institute of the Polish Academy of Sciences confirms that the S3DOC system can be used as a durable medium within the meaning of EU and Polish legal regulations.


No access account

Access for end users without the need to create an account. All you need is a unique access key to the document.



Access to documents is only possible through a unique key generated specifically for a given document. This means that you cannot see other documents in S3DOC without knowing this key. If we want to give a user access to a document we need to send him a unique access key.


Time access

The S3DOC system can operate in temporary document sharing mode. We can restrict access to the system before a specific date.


No third party

The design of S3DOC and its security mechanisms mean that no trusted party is required to ensure document permanence and access. System users can be sure that they will always have access to documents. This certainty is greater the more entities with their own nodes are included in the system. In our case, trust has been transferred from the third party to the system.



The S3DOC system has built-in mechanisms for detecting identical documents. This saves space in the data carrier.



S3DOC can be installed within a single organisation or shared between different entities. Therefore, it has built-in mechanisms for settling resource usage between entities operating on a single instance of S3DOC.



The S3DOC system consists of nodes connected in a peer-to-peer network. The document can be accessed from any node.

1. Light node configuration

In a typical configuration, each node stores only the documents that have been added to it and the identifiers of the documents stored in other nodes. This configuration reduces data redundancy.

2. High node configuration

If we want to increase the availability of data in case of a failure, we can use the configuration, in which we indicate the selected nodes as “full”. The system will automatically transfer all documents to “full” nodes as well. Thanks to this configuration we increase the security of access to data in case of failure of one of the nodes.