RC4文件加密，,基于RC4流加密算法，使

RC4文件加密，,基于RC4流加密算法，使

基于RC4流加密算法，使用扩展的16*16的S盒，32字节密钥。

import struct,sys,os,binascii"""    RC4加密算法    16*16 S盒    加密单元: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)#产生32字节密钥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#更新密钥def UpdataKey(Keyt):    Key = unCoding(Keyt)    #循环左移    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__':    #获得输入文件    if len(sys.argv)==1:        filename = input('源文件: ')    else:        filename = sys.argv[1]    try:        fin = open(filename,'rb')    except:        print('打开文件失败！')        input()        sys.exit()    print(filename)    #打开输出文件    if filename[-4:]=='.RC4':        eID = 1        key=input('输入解密密钥: ').encode()        ofilename = filename[:-4]    else:        eID = 2        key=input('输入加密密钥: ').encode()        ofilename = filename+'.RC4'    key = Coding(CreatKey(key))    key = UpdataKey(key)    #处理重名    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:        #读文件长度        filelen = struct.unpack('I',fin.read(4))[0]        print('FlieLen =',filelen,'\\n......')        while 1:            #读块大小            ps= fin.read(2)            if not ps:                #文件结束                break            packsize = struct.unpack('H',ps)[0]            #读数据            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校验错误！',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:        #获得文件长度        fin.seek(0,2)        filelen = fin.tell()        print('FlieLen =',filelen,'\\n......')        fin.seek(0,0)        fout.write(struct.pack('I',filelen))        while 1:            #读数据            dd=fin.read(65534)            if not dd:                #文件结束                break            #末尾填充            srl = len(dd)            if srl%2:                srl+=1;                dd+=b'\\0'            #crc            crc = struct.pack('I',binascii.crc32(dd))            #加密数据            dd=Coding(dd)            x = RC4(key,len(key),dd,len(dd))            key = UpdataKey(key)            #写入文件            fout.write(struct.pack('H',srl))            fout.write(x)            fout.write(crc)    fin.close()    fout.close()#该片段来自于http://byrx.net