Cryptography is a mathematical discipline that studies different ways of encryption. It actually allows communication between two sides so that a third side can not understand the message. Third side can get to the message by intercepting, eavesdropping and in some other ways, but it can not be decrypted without the right key. Throughout history, from Antiquity to present day, cryptography has progressively advanced and as time went on, it had more reliable machines and methods used to encrypt certain messages. Cryptography has been most useful in wars and today has extensive application in various security systems. At the beginning of encryption were used hieroglyphics, then squares containing letters of the alphabet and the first and the most simple device - ordinary stick (skytale). After that appears a codebook with a wheel, a system with two discs, Playfair and other systems, while in the 20th century were developed electromechanical machines Enigma and Sigaba. In recent years, appears cryptographic algorithms such as, for example, DES, AES, RSA, NTRU and ECC, and has been further developed and quantum cryptography.