Figure 2
From: Design of a cryptographically secure pseudo random number generator with grammatical evolution
Tuning of BNF grammar and genetic operators, mutation and crossover, to obtain the optimal entropy. In all combinations of the BNF Grammar as depicted in (a) where 20 generations were sufficient to obtain the optimal entropy. The initial seed leading to optimal entropy using the 15th version of BNF Grammar was secured with SHA3-512, whereas in the previous 14 versions, the hashing algorithm SHA2-512 was used to secure the initial seed. In all of the cases, the entropy remained in the range 7.92 to 7.94. (b) Values for crossover were varied from 0.0001 to 0.1 while keeping mutation fixed at 0.01. With the value of 0.0001, the optimal entropy remained consistent and the time taken to obtain the entropy was also consistent for that value. Similarly, in (c), we vary the mutation rate from 0.01 to 0.5 while keeping crossover fixed at 0.001. In this case, the most consistent value for time taken was exhibited by a mutation rate of 0.01. Finally, these two values were used with the 15th BNF grammar version to produce an optimal entropy value of 7.940560934 from 100 runs as illustrated in (d).
