Method of encryption of text information based on LSFR

Abstract

The article is devoted to the development of an LFSR-based method for encrypting text information. A method for encrypting information using a Linear Feedback Shift Register (LFSR) and dynamic keys is proposed. The long period and good statistical characterization of the sequence generated by the LFSR, while performing simple shift and addition operations, ensures high reliability and speed of the encryption process. In the proposed system, it is assumed to use several registers at the same time, the number of which is determined by the bit depth of the encrypted character. The cryptographic key used is a concatenation of the values Ki (i=1,2,...,8) entered in the shift registers: K= K1K2...K8. And the values Ki are calculated based on the components of the session key   (i=1,2,...,8) and the system time parameter. It is possible to extend the cryptographic key by increasing the bit depth of the registers. In a system with 32-bit registers, the total key length is l=25*23=28= 256 bits, and with 64-bit registers, 512 bits. The proposed method can be implemented in hardware, software, and hardware-software combination. The maximum speed of the process is achieved in a system with a hardware implementation, since the encryption of a single character in such a system is performed in just one clock cycle. It is also possible to increase the speed of the process by encrypting several characters at the same time, using the appropriate number of registers for this purpose. The resistance of the proposed cryptosystem to brute force attacks is quite high, since when using 32-bit registers, the key length will be 256 bits and the key area will be equal to 2256. Enhancing the key domain and applying dynamically changing cryptographic keys provides the necessary level of encryption process. The system is implemented to encrypt text information, but it can also be used to encrypt information in other formats.