" Why the hell hasn't Alice arrived yet? " - shouted by general Bob when he is surrounded by the enemies in the Great Hobbits War II. Bob and Alice are the two commanders of this important campaign. Two days ago, he sent a letter to inform Alice that they must unite in this place to make a combat contract. And later he received a letter supposed to be from Alice, which replied that she consensed. The enemies, led by Frodo, did it all. They intercepted the letter from Bob and made a fake one. The content had been modified that Alice must stand still. This fake information is sent to Alice then. She believed it and sent back a consensus reply. As we can see, since the letter itself is secureless and has no identity. Whether Alice believed or not, she will not move to the place of appointment. These things led to such a disaster for Bob. ----------------------------------- In network computing, we can consider the letter as your account login information on a commercia
"What the hell is going on here?" - asked myself when I saw how the teacher created and showed up a black screen with a text of "hello world" in my first day learning programming. I was there with the dream of becoming an opponent of Google, for creating massive web and mobile applications that one day I could beat them, or else, buy them. For a while feeling heavy-hearted, I realized that I had missed something important which my teacher told us before I came into the class (yes, I was late). Then we practiced with some very first problems like making simple operations, input someone's name and then output "hello <them>",... I asked Google about "hello world" right after school because I knew that I had missed the most important thing of the starter pack to be a good programmer. ------------- At first glance, it is supposed to be the most famous program and the first example of every programming language. This program tells the