Cryptographic methods of information protection: concept, characteristics, key positions

Explanatory dictionaries give us close to each other semantic definitions of the term "cryptography", differing only in the spheres of its application. Cryptography is the science of ways to protect information through various methods when it is necessary to restrict the power to familiarize with it and use it.

Cryptographic methods of information protection are the transformation of information for further transfer to an authorized person. The principle of these methods is as follows. The primary public message is encrypted, taking the form of a closed text or graphic image, called a ciphertext. Further, the cipher message is transmitted over a secure or unprotected data transmission channel to the receiving point. The authorized user performs an inverse transformation or decryption of the received message and receives the original plain text. Thus, an unauthorized person who has intercepted the encryptiongram will not be able to read it without knowing what cryptographic methods of information protection were used in encryption.

In cryptography, the concept of a key is often used, which allows for a parallel between the encrypted information and the coding system. Cryptographic means of information protection use for the encryption and decryption a unique sequence of symbols, which is called a key. Thus, when using the same cryptographic cryptographic algorithm, the result depends on the key.

Keys by their classification are divided into:

• Symmetric, that is, the sender and the recipient use the same key in the process of encryption and decryption, which ensures high confidentiality of the encrypted message, but creates problems with the functioning of keys in various systems where a large number of users;
• Asymmetric, in fact, it is considered a key pair in which the private (secret) and public keys are provided.

The principle of the key pair is as follows: a secret key is used to generate a public key, but can not be generated back by a known public key. This guarantees authentication verification when transferring information signed by an electronic digital signature (EDS).

Means of cryptographic protection of information using asymmetric keys are effective in encrypting transmitted information, not stored information. Public keys are great for replacing a regular digital signature, which is widely used in Internet payment systems.

Cryptographic methods of information protection must meet the following requirements:

1. Have a robust cipher that can withstand cryptanalysis and provide a way to open it only through a full scan of the keys. Therefore, the probability of determining the key depends on its length.
2. Ensure the stability of the cryptographic system by securely storing secret keys, not algorithms that use them.
3. Generate the amount of encoded information that does not exceed the original one.
4. Eliminate distortion and loss of information due to errors that occur during encryption.
5. Ensure minimum coding time.
6. To have consistency between the cost of encryption and the cost of source information.

Cryptographic methods of information protection are characterized by cipher resistance, which is the main indicator of efficiency. This effectiveness consists in the time or cost of funds required by the decryptor to obtain the original message from the encoded with no key. Provided there are no weak points in the encryption algorithms, which are quickly computed by the craftsmen, and a sufficiently reliable key length, these costs grow at times.