Therearetwogeneralapproachestoattackinga()encryptionscheme.Thefirstattackisknownascryptanalysis.Cryptanalyticattacksrelyonthenatureofthealgorithmplusperhapssomeknowledgeofthegeneralcharacteristicsofthe()orevensomesampleplaintext-ciphertextpairs.Thistypeof()exploitsthecharacteristicsofthealgorithmtoattempttodeduceaspecificplaintextortodeducethekeybeingused.Iftheattacksucceedsindeducingthekey,theeffectiscatastrophic:Allfutureandpastmessagesencryptedwiththatkeyarecompromised.Thesecondmethod,knownasthe()-forceattack,istotryeverypossiblekeyonapieceof(请作答此空)untilanintelligibletranslationintoplaintextisobtained.Onaverage,halfofallpossiblekeysmustbetriedtoachievesuccess.
A.plaintext B.ciphertext C.sample D.code正确答案B
