Keeping secrets by disguising them, hiding them, or making them indecipherable to others is an ancient practice. It evolved into the modern practice of cryptography—the science of secret writing, or the study of obscuring data using algorithms and secret keys.
A Brief History of Encryption
Once upon a time, keeping data secret was not hard. Hundreds of years ago, when few people were literate, the use of written language alone often sufficed to keep information from becoming general knowledge. To keep secrets then, you simply had to write them down, keep them hidden from those few people who could read, and prevent others from learning how to read. Deciphering the meaning of a document is difficult if it is written ...