单项选择题
71-75
(1) isthescienceofhidinginformation.Whereasthegoalofcryptographyistomakedataunreadablebyathirdparty.thegoalofsteganographyistohidethedatafromathirdparty.Inthisarticle,Iwilldiscusswhatsteganographyis,whatpurposesitserves,andwillprovideanexampleusingavailablesoftware.
Therearealargenumberofsteganographic (2) thatmostofusarefamiliarwith(especiallyifyouwatchalotofspymovies),rangingfrominvisibleinkandmicrodotstosecretingahiddenmessageinthesecondletterofeachwordofalargebodyoftextandspreadspectrumradiocommunication.Withcomputersandnetworks,therearemanyotherwaysofhidinginformations,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) thantheexampleaboutsuggest,allowingausertohidelargeamountsofinformationwithinimageandaudio.Theseformsofsteganographyoftenareusedinconjunctionwithcryptographysotheinformationisdoubleprotected;firstitisencryptedandthenhiddensothatanadvertisementfirst.findtheinformation(anoftendifficulttaskinandofitself)andthedecryptedit.
Thesimplestapproachtohidingdatawithinanimagefileiscalled (5) signatureinsertion.Inthismethod,wecantakethebinaryrepresentationofthehiddendataandthebitofeachbytewithinthecovertimage.Ifweareusing24-bitcolortheamountandwillbeminimumandindiscriminatetothehumaneye.
A．Cryptography
B．Geography
C．Stenography
D．Steganography
如果该S盒的输入110011，则其二进制输出为（）
