# for python 3.0# from 李勃import struct,sys,os,binascii"""  RC4加密算法  16*16 S盒  加密單元:short"""def RC4(pkey,keylen,pin,dlen):  N=65536  S = list(range(N))  j = 0  for i in range(N):    j = (j + S[i] + pkey[i%keylen])%N    temp = S[i]    S[i] = S[j]    S[j] = temp  i = j = 0  pout= b''  for x in range(dlen):    i = i+1    j = (j + S[i])%N    temp = S[i]    S[i] = S[j]    S[j] = temp    pout += struct.pack('H',pin[x]^S[(S[i]+S[j])%N])  return(pout)# bytes->shortdef Coding(data):  if(len(data)%2):    data+=b'/0'  dlen = len(data)//2  return(struct.unpack(str(dlen)+'H',data))# short->bytesdef unCoding(data):  d=b''  for i in range(len(data)):    d += struct.pack('H',data[i])  return(d)#產生32字節密鑰def CreatKey(Keyt):  pl = len(Keyt)  Key=b''  r=0  for i in range(32):    k=(Keyt[r%pl]+i)%256    Key+= struct.pack('B',k)    r+=1  return Key#更新密鑰def UpdataKey(Keyt):  Key = unCoding(Keyt)  #循環左移  Key = Key[1:] + struct.pack('B',Key[0])  tem=0  #求和  for i in range(len(Key)):    tem += Key[i];  Keyo=b''  #Xor  for i in range(len(Key)):    Keyo += struct.pack('B',(Key[i]^tem)%256)    tem += Keyo[i]>>3    tem = tem % 256  return(Coding(Keyo))if __name__ == '__main__':  #獲得輸入文件  if len(sys.argv)==1:    filename = input('源文件: ')  else:    filename = sys.argv[1]     try:    fin = open(filename,'rb')  except:    print('打開文件失敗！')    input()    sys.exit()  print(filename)  #打開輸出文件  if filename[-4:]=='.RC4':    eID = 1    key=input('輸入解密密鑰: ').encode()    ofilename = filename[:-4]  else:    eID = 2    key=input('輸入加密密鑰: ').encode()    ofilename = filename+'.RC4'  key = Coding(CreatKey(key))  key = UpdataKey(key)   #處理重名  while os.path.exists(ofilename):    ofilename = os.path.dirname(ofilename)+ '//副本 '+ os.path.basename(ofilename)  fout = open(ofilename,'wb')  print(ofilename)  #解密  if eID==1:    #讀文件長度    filelen = struct.unpack('I',fin.read(4))[0]    print('FlieLen =',filelen,'/n......')    while 1:      #讀塊大小      ps= fin.read(2)      if not ps:        #文件結束        break      packsize = struct.unpack('H',ps)[0]      #讀數據      dd=fin.read(packsize)      #解密      dd=Coding(dd)      x = RC4(key,len(key),dd,len(dd))      key = UpdataKey(key)      #crc      crc = struct.unpack('I',fin.read(4))[0]      if binascii.crc32(x)!=crc:        print('CRC32校驗錯誤！',crc,binascii.crc32(x))        input()        sys.exit()      fout.write(x)    #裁剪末尾填充位    fout.truncate(filelen)  #加密  elif eID==2:    #獲得文件長度    fin.seek(0,2)    filelen = fin.tell()    print('FlieLen =',filelen,'/n......')    fin.seek(0,0)    fout.write(struct.pack('I',filelen))    while 1:      #讀數據      dd=fin.read(65534)      if not dd:        #文件結束        break      #末尾填充      srl = len(dd)      if srl%2:        srl+=1;        dd+=b'/0'      #crc      crc = struct.pack('I',binascii.crc32(dd))      #加密數據      dd=Coding(dd)      x = RC4(key,len(key),dd,len(dd))      key = UpdataKey(key)      #寫入文件      fout.write(struct.pack('H',srl))      fout.write(x)      fout.write(crc)  fin.close()  fout.close()  print('OK!')  input()