A Cloud-User Protocol Based on Ciphertext Watermarking Technology

Algorithm 8

Fixed Hamming distance coding.

Input: , L

Output:

   = empty set

  threshold=L

  flag=1

  while  not reach time-limit  do

   random generate a temp watermark t of length L

   flag=1

  for  each w in   do

  if  sum(XOR()<threshold)  then

   flag=0

   break

  end

  end

  if  flag  then

   Add t into

  end

  end

  return