It wasn’t so long ago that cryptographic technologies commonly employed today were restricted to cutting edge research and discussions among university professors. Notably, public-key encryption only emerged in the seventies, with the early example being the RSA encryption algorithm and the Diffie-Hellman key exchange.
Years later, these cryptographic technologies found their way into the daily lives of millions of people mainly in the form of online electronic communication. Though these modern encryption techniques are common, they are rarely understood by users beyond the level of basic concepts and ideas.
However, something happened in the past couple of years that sparked an explosion of new tech companies and their salesmen blazoning the advent of a new era of cryptography brought about by the one and only “blockchain”. The blockchain is supposed to be key to some magical cryptographic paradise, where secure peer-to-peer transactions are decentralized and impossible to hack, though rarely do we hear that the most famous blockchain, the bitcoin blockchain, is far from peer-to-peer (but rather, it is node-to-node), and that with improper usage of encryption algorithms, even theoretically unbreakable encryption can be easily attacked.
The reason why I first wrote “blockchain” in quotation marks is that the term is very vague to the point where it does not have meaning anymore. Sure, it is a useful term to introduce the concept, such as the word “vehicle”. But when you start selling a “vehicle”, you may be selling a bicycle where the customer expects a tractor. And so it is with a blockchain. Any blockchain is actually a form of a hash tree (proposed by Ralph Merkle back in 1979), where a tree is a generalization of hash chains and hash lists.
Along with public encryption methods, it is evident that the ingredients for this revolutionary blockchain concept have been around for quite some time now (likewise ideas for digital currencies and secure transaction systems). I believe it just happens to be now in the last couple of years that we have uncovered truly practical usage of Merkleing and asset transactions. Its proper application is not straightforward, as evidenced by the many problems of the bitcoin blockchain for instance. It takes skill and experience to develop the idea further into a bulletproof and proven product.