Hybrid Approach for PRNGs using BBS and Dithering Technique

Objectives: The cryptographically secure pseudo-random number generator Blum Blum-Shub (BBS) is a simple algorithm with a strong security proof, all of number generators that produced by BBS will be converted to (0, 1) using simplest form called Parity (even parity bit and odd parity bit).This approach proposed new method for extending bit space acquired from BBS based on dither matrix instead of (Parity) feature with saving of strength and security of crypto-key. Methods/Statistical Analysis: We used dithering techniques (2*2, 4*44) that provide continuous image of higher colors on a display of less color depth, for improving numbers that generated by BBS. And used some of statistical tests for measuring crypto-key strength such (run, poker, serial and frequency tests).The proposal algorithm has been programmed using c#.net 2013 Findings: This approach provides high extended on number space that generated from BBS by using Dithering techniques (2*2, 4*4), with saving of crypto-key randomness and guarantee passing of statistical tests, dithering techniques (8*8) is unsuitable for this purpose. Although, it provides height extension but decrease the randomness of key numbers. Application/Improvements: This approach proposed to replace (Parity) property with dithering techniques. It's replaces max of gray level in dithering such (256) in 8 bit image with value of n, (p*q) in BBS, this may convert the domain of any number sets to dithering domain to be suitable for purpose.