以下关于VPN的叙述中，正确的是（）

（1）is the science of hiding information.Where as the goal of cryp to graphy is to make data unreadable by a third party.the goal of steganography is to hide the data from a third party.In this article,I will discuss what steganography is,what purposes it serves,and will provide an example using available software. There are a large number of steganographic（2）that most of us are familiar with(especially if you watch a lot of spymovies),ranging from invisible inkandmicrodotstosecretingahiddenmessageinthesecondletterofeachwordofalargebodyoftextandspreadspectrumradiocommunication.With computersandnetworks,there arem any other ways of hiding informations,suchas: Covertchannels(c,g,Lokiandsomedistributeddenial-of-servicetoolsusetheInternetControl（3）Protocol,orICMP,asthecommunicationchannelbetweenthe“badguy”andacompromicyedsystem) HiddentextwithinWebpages Hidingfilesin“plainsight”(c,g.whatbetterplaceto“hide”afilethanwithanimportantsoundingnameinthec:\winntsystem32directory) Nullciphers(c,g,usingthefirstletterofeachwordtoformahiddenmessageinanotherwiseinnocuoustext) steganographytoday,however,issignificantlymore（4）than the example about suggest,allowing ausertohidelargeamountsofinformationwithinimageandaudio.Theseformsofsteganographyoftenareusedinconjunctionwith cryptographysothe information is double protected;firstitisencryptedandthenhiddensothatanadvertisementfirst.find the information(an often difficult task inandofitself)and the decryptedit. The simple stapproachtohidingdatawithinanimagefileiscalled（5）signatureinsertion.In this method,we can take the binaryrepresentationofthehiddendataandthebitofeachbytewithinthecovertimage.If weareusing 24-bitcolor the amount and will be minimum and indiscriminate to the human eye.

在DES算法中，需要进行16轮加密，每一轮的子密钥长度为（）

67mod119的逆元是（）

AES结构由以下4个不同的模块组成，其中（）是非线性模块

杂凑函数SHAI的输入分组长度为（）比特

设在RSA的公钥密码体制中，公钥为（c，n）=（13,35），则私钥为（）

两个密钥三重DES加密：C=CK1[DK2[EK1[P]]],K1≠K2，其中有效的密钥为（）

包过滤技术防火墙在过滤数据包时，一般不关心（）

以下关于网络流量监控的叙述中，不正确的是（）

以下关于VPN的叙述中，正确的是（）