Security and Communication Networks / 2019 / Article / Alg 2

Research Article

Security Cryptanalysis of NUX for the Internet of Things

Algorithm 2

Algorithm for linear approximations on NUX.

Input: S-box , Bias threshold .
Output: A linear approximation with the best bias.
Data: The number of active S-boxes in i rounds .
   The number of active S-boxes of the i-th round .
Generate the LAT of S-box.
Store all 2, 4 and the corresponding input/output masks in LAT in the table
  for Each of 8 S-boxes in the first round do
  for all non-zero entities in LAT do
   if S-box is in   then
     , .
     Store them in .
    else
     , .
      Store them in .
    Calculate , , , , and store them in .
    Calculate , , , , and store them in .
    Update to be 1.
    The bias is recorded as .
  for   to   do
    if    then
     
     Travel to get , and its corresponding bias
    else if    then
      
      Travel to get , and the corresponding bias
    Compute the total bias, and keep ones greater than threshold
    Calculate , , , , and store them in .
    Update the number of active S-boxes and bias
  for Each of 8 S-boxes in the first round do
  for all non-zero entities in DDT do
    Find the largest and store it in
    Output linear approximations with bias