Nowadays, with the development of data networks more importance is given to the information safety than before. Information is both a product and a major competitive advantage, for this reason many things that some people try to keep in secret, other will necessarily want to unveil. That is why when sending sensitive data over insecure channels, various encryption algorithms should be used. Cryptology or knowledge system, proposes a scientific approach to study these algorithms, it is sub-divided into cryptography (the science of privacy and encryption) and cryptanalysis (the science of deciphering the information without the knowledge of special keys).

In broad terms, encryption is a set of ways to transform commonly available information into a closed data and vice versa; it is used to transfer information, or to store it in unreliable sources, securing it in its three components:

• Identifiability - a procedure of authentication (authentication) of the sender of the information. Thus, in the event of failure by the fact of sending the data is still to be confirmed.
• Integrity - a guarantee that the information is not in any way changed or distorted during storage and subsequent transmission.
• Privacy – during the transmission and the storage of the data, unauthorized users will not be able to access the encrypted information.

In the same time, this measure is not a hundred percent guarantee of data security, because almost any encryption system can be hacked. Its main goal is only to complicate as much as possible the access to the information, in the case if the encrypted data falls into the wrong hands. With no key (an input, by which the original text is encrypted and then lately decrypted), unauthorized users will not be able to violate the secrecy of the information.

If the same key is used for both, encryption and decryption then the cryptosystem is symmetric. The algorithm which will be used for the transformation of the information is chosen by both parties in advance, and the key is kept in secrecy. Symmetric ciphers have advantages and disadvantages. The advantages include the simplicity and the operating speed, the main disadvantage is the risk of compromission of the keys when used with a large number of subscribers. Also with this method, it is impossible to establish authorship, as the key is known to all participants of the exchange.

Asymmetric encryption or cryptographic communication system of public-key uses two different keys: one - known to all parties in order to encrypt the message and a secret one known only to the receiving party and used for decryption. The advantage of this system is that the public key can be sent over insecure communication channels, and be used for quite a long time without any update. The disadvantage is the difficulty of making changes to the encryption algorithm and comparatively a large length of the symmetric key

In addition to these systems, there is a so-called keyless encryption, for which pseudorandom number generators or single permutations are usually used.