A Method of Cryptographically Strong Pseudorandom Sequences Generation Based on the Blender

The paper deals with a method for generating cryptographic pseudorandom sequences (PRSs) applicable in data security tasks in cyber-physical systems. The following methods were used in the study: PRS generation based on cryptographic algorithms in accordance with the recommendations of NIST SP 800-90; PRS testing methods (NIST 800-22 and NIST 800-90B tests); methods and tools for evaluating the quality of pseudorandom sequences using min-entropy, Pearson criterion and linear complexity. A method for generating cryptographically strong PRSs that consists of arbitrary length blocks is proposed. The key component of the proposed method is a special randomness extractor function called blender. In addition, elements of the key expansion mechanism of “Kuznyechik” cipher (Russian GOST R 34.12-2015) are embedded in the generation scheme. A number of modifications to the original algorithm were made. An increase in cryptographic strength is achieved with the help of individual keys during the output PRS blocks formation. Additional randomness is introduced due to a special structure of iterative constants that use key information. Evaluation of the output sequences quality confirms the operability and efficiency of the proposed generation method.