Algorithm 2 Image encryption.

Require: $genesisblock\left(Gb\right)$ Ensure: $Image\left(P\right)$  Get m x n from P  initialize $y=uint8\left(zeros\right(mxn\left)\right)$  initialize K = 1  $sh=rand(1,512\times 512)$  $[t,Ind]=sort\left(sh\right);$  while i ≤ m do   while i ≤ n do    $temp=x(i,j:j+31);$    $y(i,j:j+31)=\left(Gb\right(k,:)\oplus p(i,j:j+31\left)\right);$    $Gb(k+1,:)=uint8(sha256hasher.ComputeHash(y(i,j:j+31)\left)\right);$    increment k by 1   end while  end while