Securing Digital Images through Simple Permutation-Substitution Mechanism in Cloud-Based Smart City Environment
Algorithm 1
Encryption algorithm.
Input: Plain image
Parameters:,β, ,α, A//Used for iterating chaotic maps.
Output: Cipher image and decimal values
= size //Get image dimension.
//Compute the hash value for image using SHA-256 algorithm.
//Convert the 256 bit hash value to 32 integer values , where each integer composed of 8 bit.
= ;
= ;
= ;
= ;
//Update initial key parameters (,β, ,α) using ,,, and
;
;
;
;
= Logistic-Chebyshev //Using the updated key parameters , operate Logistic-Chebyshev map for times to generate sequence , wherever the size of is and c denotes the number of color channels.
= Logistic-Sine //Using the updated key parameters , operate Logistic-Sine system for times to create sequence .
//Convert sequence into integer values.
;
//Permute the input image using the sequence and chaotic magic transform method presented in [15].
//Collect the first 256 unequal elements in the sequence to construct the substitution-box (S-box).
//Substitution process.
for
for
for
;
end
end
end
//Cascade both sequences ( and ) to generate the key sequence Key.
