Note: Note: this article is a translation - with the help of Google Translate - of an article published in French on the https://www.publish0x.com/opinions/blockchain-et-cryptomonnaie-lenvers-de-la-medaille-la-technologie-xmwy

For ten years, the expressions blockchain and cryptocurrency have appeared in the universe of technologies. It is the "Holy Grail", the "miracle" solution to technology, to all social and economic problems. Thanks! We are all looking for THE Truth and happiness ... with the least possible effort.

Some "evangelists" have sniffed the bargain and have exploited "this new trend". A "tweet", "a share" on social networks, can turn a meeting of friends into a monster event in the streets! And why not wealth for everyone with a world currency safe from all eyes? And why not a model of social organization based on the structure of the blockchain?

There were only good words for and the promise of a better future for all. No one can oppose this speech and nobody wants to question these promises. "Believe in your dreams, even in a utopia! ". In the euphoric phase, it is wrong to post a different opinion or dissent.

Without being a pain in the neck, let's get back to reality.

Technology.

The blockchain technology comes from the structure of the first databases in sequential mode, mostly stored on punch cards and magnetic tapes. This structure has been partially abandoned to be replaced by indexed relational databases accessible on disks, faster and less energy intensive.

The sequencing of block sequences, cryptography, multi-node distribution, and governance by algorithms as trusted third parties have propelled this technology as a valid alternative to current IT systems. It offers the characteristics of trust because permanent, non-modifiable, safe, anonymity and transparency.

While being a response to the management of computer data, these characteristics have a special meaning on the governance of our societies where we denounce the manipulation of information, the centralization of powers, corruption and collusion. The blockchain appears as a solution to all these concerns.

However, blockchain applications are based on a "new paradigm": the resources are unlimited and "The sky's the limit". Blockchain and its Bitcoin currency seem to offer all the hopes of changing the world!

 However, over time, implementation has proved more difficult than anticipated. Several obstacles have sown the course:

• 10-minute block validation time impede blockchain adoption for real-time financial transactions. Several solutions are envisaged to improve performance such as POS, dPOS and others, but for the moment, none seems to have reached a good enough level of scaling.
• The increase in "mining" farms and the amount of energy needed to produce the blocks, is creating a growing demand for electricity leading to increased costs and a significant environmental impact.
• The treatment of increasingly large blockchains requires pushing the limits in the size and speeds of storage hardware, processors and virtual memories. As in all races, the last few miles are more difficult and expensive to cross.
• Transparency, permanence and unchangeable, which are characteristics of the blockchain, face legislation such as the GDPR and equivalents in different countries. The blockchain which was intended beyond the legislations and beyond the countries, is now faced with having to conform to them under penalty of being relayed with the rank of the illegal activities.

Thus, several challenges are to be noted while preserving the main characteristics of the blockchain:

• Achieve transaction and efficiency speeds comparable to existing systems.
• Achieve lower operating costs than environmentally sound systems. In a context of "saving the planet" and a better distribution of wealth, it would be necessary to target social acceptability.
• Make the blockchain conform to the different legislations of GDPR. It would be easier to build systems that conform to the laws than to want to change them. In general, countries do not like to be dictated how to govern on their territory.