Introduction
Incryptanalysis,aknownplaintextattackisanattackmode,whichmeansthattheattackerhasmasteredacertainsectionofplaintextxandthecorrespondingciphertexty.
Inallcryptanalysis,itisassumedthattheattackerknowsthecryptosystembeingused.ThisassumptioniscalledtheKockhoffhypothesis.Theknownplaintextattackalsoassumesthattheattackercanobtainpartoftheplaintextandthecorrespondingciphertext,suchasinterceptingthefirstpartoftheinformation,andobtainingtheencryptionmethodthroughthistypeofattack,soastofacilitatethecrackingofthelatterpartoftheciphertext.
Hillciphersrelyononlyciphertextattacks,whicharedifficulttocrack,butareeasiertobreakthroughknownplaintextattacks.
Relatedterms
Ciphertextonlyattack
Skiptonavigationandsearch
Incryptographyorcryptanalysis,Ciphertextonlyattackisanattackmodethatreferstoanattackwhenonlytheencryptedtext(ie,ciphertext)isknown.Thisschemecanbeusedtoattacksymmetriccryptosystemsandasymmetriccryptosystemsatthesametime.
Theciphertext-onlyattackhopestoachieveseveralgoals,arrangedaccordingtothedegreeofsuccess:
Getsomeinformationintheoriginalplaintext.
Gettheoriginalplaintext.
Learnthekeyfordecryption.
Theexhaustivemethodisaciphertext-onlyattack,buttheexhaustivemethodisgenerallyconsideredwhendesigningthealgorithm.
Selectplaintextattack
Skiptonavigationandjumptosearch
Incryptographyorcryptanalysis,selectplaintextattackreferstoItisamodeofattack.Theattackerhasaccesstotheencryptionmachineandcanconstructciphertextcorrespondingtoanyplaintext.
Inthisattackmode,theattackercanarbitrarilyselectacertainamountofplaintextinadvance,encrypttheattackedencryptionalgorithm,andobtainthecorrespondingciphertext.Theattacker'sgoalistoobtainsomeinformationabouttheencryptionalgorithmthroughthisprocess,sothattheattackercanmoreeffectivelycracktheinformationencryptedbythesameencryptionalgorithm(andrelatedkeys)inthefuture.Intheworstcase,theattackercandirectlyobtainthekeyfordecryption.
Thisattackmodedoesnotseemrealisticatfirst,becauseitishardtoimaginethatanattackercanchooseanyinformationandasktheencryptionsystemtoencryptit.However,inpublickeycryptography,thisisaveryrealisticmodel.Thisisbecauseinthepublickeycryptographicscheme,theencryptionkeyispublic,soanattackercandirectlyuseittoencryptarbitraryinformation.
Selectciphertextattack
Skiptonavigationandjumptosearch
Incryptanalysis,SelectciphertextattackreferstoAnattackmethod.Theattackerhasaccesstothedecryptionmachineandcanconstructtheplaintextxcorrespondingtoanyciphertext.
Inthisattackmodel,thecryptanalystcollectsacertainamountofciphertextarbitrarilyinadvance,letstheseciphertextsbedecryptedthroughtheattackedencryptionalgorithm,andobtainsthedecryptedplaintextthroughanunknownkey.