Abstract: The invention relates to telecommunications and computer engineering, and especially to cryptographic methods and devices intended to encrypt numerical data. The inventive method comprises the steps of working out K≧data blocks containing P≧1 elements of the binary information code and of converting data blocks under control of an encryption key. The novelty of the system consists in that D≧1 binary vectors are additionally generated, that the data blocks are formed by linking the binary vectors to the corresponding elements of the binary information code, that the binary vectors are generated at random and pseudorandom, that they are linked to the corresponding elements of the binary information code, and that this linkage is based on the secret key.