Algorithm 1: Image Sharing

Input: Image M, Encryption keys Xt, $t=1, 2, \dots , n$.

Output: Sharing images C(t), $t=1, 2, \dots , n$.

Step 1: A set of pixels (Pi,j, …, Pi,j+k−1) is extracted from Image M. The polynomial $P_{i,j+k-1}{x}^{k-1}+P_{i,j+k-2}{x}^{k-2}+\dots +P_{i,j}$ is generated using the set of pixels (Pi,j, …, Pi,j+k−1).

Step 2: Substitute the Encryption key Xt, $t=1, 2, \dots , n$ through 256 Galois field into the polynomial $P_{i,j+k-1}{x}^{k-1}+P_{i,j+k-2}{x}^{k-2}+\dots +P_{i,j}$ to obtain n encrypted pixel values y(t)i,j, where y(t)i,j $=P_{i,j+k-1}{x}_t{}^{k-1}+P_{i,j+k-2}{x}_t{}^{k-2}+\dots +P_{i,j}$, $t=1, 2, \dots , n$.

Step 3: The encrypted pixel values y(t)i,j are divided into 8-bits, and each bit is put into the pixels of the shared image C(t) in order (C(t)i,j, …, C(t)i,j+k−1), and it is called the P part, if $k\le 7$, because $k<8$ cannot put all the bits at once, so the remaining bits are put in order again and the remaining vacant part is called Part B.

Step 4: Repeat Step 2 and Step 3 until all set of pixels (Pi,j, …, Pi,j+k−1) have been processed.

Step 5: Output n encrypted shared images C(t),$t=1, 2, \dots , n$.