Frequently Asked Questions

What is cryptography?

The process of using a system to write something in code (cipher), is called encrypting, encipheing or encoding; whereas changing it back again is called decrypting, deciphering or decoding. The code breaker's job is to decrypt the cipher text without knowing the system used in the first place to encrypt the plain text.

The word cryptography comes from the Greek, kryptos (kruptos) meaning 'hidden' and graphi (grafh) meaning 'writing'. Code breaking is all about uncovering hidden writing.

For example, we could change the plain text HELLO into the cipher GDKKN by taking one from each letter. However, it would not require much effort to decode this. Clearly much more cunning methods need to be empolyed.

In fact, most encryption systems are based on either Substitution (replacing each letter in the plain text with a different symbol) or Transposition (changing the order of the letters in the plain text).