This blog is about Cryptography - the Science of Secret Writing. Cryptography is all about codes and ciphers used to encrypt messages and information. A cipher is an algorithm used to encrypt text so not everyone can read it. Ciphers almost always have a key. A key is a piece of information used to encrypt and decrypt messages. I will explain more about keys later. In cryptography, to illustrate an example of a cipher we often use the imaginary people Alice, Bob, and Eve. Alice wants to send a message to Bob but does not want anyone but Bob to be able to read it. Eve wants to intercept the message and read it. Alice has to encrypt her message with a cipher and Eve has to perform cryptanalysis - the process of decrypting a message without knowing the key. Cryptography is all about the battle between the codemakers and the codebreakers. The codemakers invent ciphers while the codebreakers find ways to break ciphers. Cryptography involves both Math and English. To be good at cryptography you need have a good sense of the English language and you also need to be strong in Math.