for KEYSIZE in range(2,40):
  hamming_dist1 = hamming_distance(encodedstring[0:KEYSIZE],encodedstring[KEYSIZE:2*KEYSIZE])
  hamming_dist2 = hamming_distance(encodedstring[2*KEYSIZE:3*KEYSIZE],encodedstring[3*KEYSIZE:4*KEYSIZE])
  hamming_dist3 = hamming_distance(encodedstring[4*KEYSIZE:5*KEYSIZE],encodedstring[5*KEYSIZE:6*KEYSIZE])
  norm_hamming_distance = (hamming_dist1+hamming_dist2+hamming_dist3)/KEYSIZE
  if norm_hamming_distance <= min_norm_keysize:
    list_keysize.append(KEYSIZE)
    min_norm_keysize = norm_hamming_distance