ABSTRACT
Most applications communicate by using the protocols the people have already discussed, notably Transmission Control Protocol/Internet Protocol. However, there are protocols that allow particular apps running on different systems to communicate with one another at a higher level of abstraction, that is, treating the entire pipe system as a communication mechanism without having to pay attention to the details of how it works. Working at this higher level of abstraction also makes it easier to see that certain types of traffic flows should not be allowed. Security was not a consideration when it was defined, because email was a way to move simple text from a sender to a receiver. Security mechanisms, minimal to start with, have not kept up with all this new functionality. The nature of email means that security is inherently difficult. Although the long-term usefulness of blockchains remains an open question, they create a complex security environment which is worth exploring.
