fs.readFile('./downsuccess/'+name+'', {flag: 'r+', encoding: ''}, function (err, data) {
 console.log('讀取中')
 if(err) {
 return;
 }
 let b = new Buffer(data);
 let c = b.toString('hex');
 let cipherBuffer = _this.cipher(data);
 fs.writeFile('./downsuccess/'+name+'',cipherBuffer,[],function(){
 console.log(`${name}加密完成`);
 _this.downAll(_this.downList,_this.downCall)
 })
 });
export function cipher (buf) {
 var encrypted = "";
 var cip = crypto.createCipher('rc4', '密匙');
 encrypted += cip.update(buf, 'hex', 'hex');
 encrypted += cip.final('hex');
 return encrypted
};