We have known that PKO implemented a durable medium solution based on blockchain technology for a few weeks. Now the bank has announced that it is beginning its first round of customer document delivery with the use of the new technology. In the next few days over 5 million customers will receive new product regulations in a digital format.

Related: PKO Introduces Blockchain Based Durable Medium. First Document Distribution Planned for September

According to the bank, this is the largest-scale blockchain technology use in banking in Europe. The solution was developed in cooperation with the National Clearing House (KIR) and technology providers. A collaboration with the Polish-British company Coinfirm was an important element on the bank's side. The new service is based on blockchain technology and a qualified electronic seal offered by the KIR.

- Blockchain has an enormous potential to increase the competitiveness of the Polish banking sector. It's a relatively young technology and there are new uses constantly being found for it all over the world. PKO is following its digitization-oriented strategy and the full implementation of this blockchain-based solution is the next step on our path - says Adam Marciniak, PKO vice president.

Related: A bank built on blockchain - a beginner's guide, part 4

According to PKO the current document delivery is related to changes in regulations imposed by the European and national PSD II regulations. They regulate third-party access to bank functionalities and data. Electronic correspondence will be sent to customers who agreed to receive information through this channel. This currently includes over 5 million people, which is more than half of PKO's customers.

The bank's electronic correspondence will include a 64-character, unique hash identifier for the document and a link to the bank's website where, without the need to log in, they can easily paste their hash identifier or upload a previously downloaded document and find out if the document is authentic and when it was last modified. This solution will allow customers to retain access to the documents even after they are no longer in business with the bank and be sure that they weren't modified.