Securing Digital Images through Simple Permutation-Substitution Mechanism in Cloud-Based Smart City Environment

Table 1

Outcomes of NIST SP 800-22 tests for the cipher image Enc-Sailboat and its used key stream that was generated from chaotic maps.

Test name		-value		Passed
		Enc-sailboat	Key stream
Random excursions variant (x = 1)		0.758288	0.911716	√
Rank		0.277427	0.023295	√
Random excursions (x = 1)		0.759421	0.324551	√
Long runs of ones		0.538239	0.047194	√
Overlapping templates		0.309669	0.864874	√
Frequency		0.275713	0.305835	√
Linear complexity		0.299882	0.348444	√
Block-frequency		0.469785	0.646149	√
Runs		0.423022	0.456241	√
No overlapping templates		0.686946	0.311721	√
Universal statistical		0.943058	0.638841	√
Spectral DFT		0.912314	0.890517	√
Approximate entropy		0.358094	0.373851	√
Serial	Test 1	0.752991	0.278112	√
	Test 2	0.551133	0.465868	√
Cumulative sums	Reverse	0.388377	0.348202	√
	Forward	0.483105	0.282021	√