《应用密码学》课程试卷(1)（application cryptography (1)）

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1、《应用密码学》课程试卷(1)（Applicationcryptography(1)）Fillintheblankswiththeanswersinthefirstquestion.15empty,eachempty1point,15points)1.InAES,whenthelengthoftheclearandencryptionkeysis128-bit,whenencryptionisusedThenumberofiterationsis...wheel.ThecleargroupingofDESalgorithmsis...bits,and

2、thevalidkeylengthis________bits.ThemessageofSHAis_____.4.ThefourmodesofDESrunare:electroniccode(ECB)modepassword,______________,Passwordfeedback(CFB)mode,______________.5.IftheperiodofsequenceproducedbyLFSRofclassnis...,thissequenceiscalledmsequence.6.IntheprocessofMD5algorith

3、m,beforecompressionprocessing,themessageshouldbefilled,Integertimesthelengthofthefilledmessageis_______.7.Inthe(k,n)-secretsegmentationscheme,atleastoneoftheparticipantscanreconstructthesubjectDivisionofsecrets.8.Thekeycanbedividedintosessionkeyand______________accordingtoitsd

4、ifferentUSESThekeyisalsocalled...9.Theoutputsequenceofalinearfeedbackshiftregisterisassumedtobe100100011110101,ifThisisaperiodoftheoutputofthelinearfeedbackshiftregister,inwhichthelengthis1Thelengthofthenumberofthenumberofthenumberofthenumberof......a.ThefollowingfigureisS1int

5、heSbox,andiftheinputis(101011),theoutputshouldbe...Si0one23456789101112131415one014413one2151183106125907one0157414213one1061211953824one14813621115129731050315128249one7511314100613Putyourjudgmentinbracketsbehindthetitle.The"squareroot",thewrongtype"x".Ten,onepoint,tenpointsp

6、erproblem.1.Forasecuremessagedigestfunction,findtwodifferentmessagesandmakethemessagedigestIt'snotfeasibletocomputethesamevalue.(a)2.IntheparameterselectionofRSApasswordsystem,iftheencryptionindex(publickey)istoosmall,ItwillaffectthesecurityofRSApasswordsystem.(a)3.Inordertosa

7、vethesystemresources,severaluserscanbeselectedintheparameterselectionofRSApasswordsystemUsethesamemodulen.4.Theso-calledpseudo-randomsequence,whichistheinterceptofakeystreamofanylength,willnotleakthefollowingMoreinformationaboutthemachinesequence.(a)TheECCciphersystemiscompare

8、dtotheRSApasswordsystem,andinthesamesecuritycondition,Therequ