A story of Alice and Bob

Once upon a time, there lived two people named Alice and Bob. They were close friends and loved to do everything together. One day they realized they had to break up and Bob had to move to the other end of the Earth for work. He told her, "don't worry! I will write letters to you frequently, letting you know how I'm doing". But Alice was not convinced because she was afraid would open up his or her letters and try to read what they are saying (sometimes they talk about super secret information that they don't want anyone else to know). They sat down to come up with the best, unbreakable cryptosystem ever invented, and from then on swore to use code from then on. Alice was still not fully convinced, so she decided to send Bob a fake message encrypted using the cryptosystem. Fortunately, they found out their mutual frienemy, Eve, had somehow cracked the uncrackable cryptosystem and started gossiping to many people about the letter that Alice wrote. Alice quickly searched for Eve, and asked how she cracked their unbreakable code. Eve says she eavesdropped when Alice and Bob were coming up with the unbreakable code because they were walking about in a public park! The moral of this story is to always plan your secret codes behind closed doors where all the doors are tightly insulated from the outside world. Also, watch out for people who's name is Eve.