羊城杯2021-babysmc-wp

exe文件，被smc混淆了，動態調試到主函數，發現邏輯是將輸入的字符三個為一組，經過一系列變換后作為下標，通過一個固定的s盒轉換為四個字符。已知明文，可以通過爆破求解。

s=[  0xE4, 0xC4, 0xE7, 0xC7, 0xE6, 0xC6, 0xE1, 0xC1, 0xE0, 0xC0,
  0xE3, 0xC3, 0xE2, 0xC2, 0xED, 0xCD, 0xEC, 0xCC, 0xEF, 0xCF,
  0xEE, 0xCE, 0xE9, 0xC9, 0xE8, 0xC8, 0xEB, 0xCB, 0xEA, 0xCA,
  0xF5, 0xD5, 0xF4, 0xD4, 0xF7, 0xD7, 0xF6, 0xD6, 0xF1, 0xD1,
  0xF0, 0xD0, 0xF3, 0xD3, 0xF2, 0xD2, 0xFD, 0xDD, 0xFC, 0xDC,
  0xFF, 0xDF, 0x95, 0x9C, 0x9D, 0x92, 0x93, 0x90, 0x91, 0x96,
  0x97, 0x94, 0x8A, 0x8E]
data="H>oQn6aqLr{DH6odhdm0dMe`MBo?lRglHtGPOdobDlknejmGI|ghDb<4"
data=list(data)
flag=[0]*45
def shl(c, b):
  return (c << b) & 0xff
def sar(c, b):
  temp = bin(c)[2:].rjust(8, '0')
  if temp[0] == '0':
    return (c>>b)&0xff
  else:
    for _ in range(b):
      temp='1'+temp[:7]
    return int(temp,2)
count=0
for m in range(8):
  for i in range(32,126):
    for j in range(32,126):
      for z in range(32,126):
        a1 = s[sar(i, 2)%len(s)] ^ 0xa6
        a2 = s[(sar(j, 4) | shl(i & 3, 4))%len(s)] ^ 0xa3
        a3 = s[(shl(j & 0xf, 2) | sar(z, 6))%len(s)] ^ 0xa9
        a4 = s[(z & 0x3f)%len(s)] ^ 0xac
        if (a1 == ord(data[count]) and a2 == ord(data[count + 1]) and a3 == ord(data[count + 2]) and a4 == ord(
                data[count + 3])):
          count += 4
          print(chr(i),end="")
          print(chr(j), end="")
          print(chr(z), end="")
for i in range(32, 126):
  for j in range(32, 126):
    for z in range(32, 126):
      a1 = s[sar(i, 2) % len(s)] ^ 0xa6
      a2 = s[(sar(j, 4) | shl(i & 3, 4)) % len(s)] ^ 0xa3
      a3 = s[(shl(j & 0xf, 2) | sar(z, 6)) % len(s)] ^ 0xa9
      a4 = s[(z & 0x3f) % len(s)] ^ 0xac
      if (a1 == ord(data[count]) and a2 == ord(data[count + 1])):
        count += 4
        print(chr(i), end="")
        print(chr(j), end="")

最后三位爆不出，結果發現沒有三位，就兩位，卡了好久。。。。