IASB kodutöö (0)

Murda Vigenere’i šifri abil moodustatud krüptogramm, mille avatekst on
eeldatavasti inglisekeelne:
XYXXWYXXLTYAUCWRLWWIPPCXITEEPRMTSTSEJONNOSPPTHLKSYGHSTERSIMJRNPZVTHGSBSETSVOCXVKJKZXRXNSVKGPPBSYRDKZVSGZXGVMMSZILVLTDJXIILFJKCSKFTLOKEKXILUGIKKJSZYYJMTJKKIEFFATACSRYZKXVITYAUCECTXKKHWDXSLUUXYXISTVIILTXHPXKEJSTSFPMMWOGWVEKATIIIXXLXPXYXWLNTCUBXUUKIITXGACHIXFKUCXFKZFGLEPUDJKPPZSNFMILRMBZGIMKFFCKHWVGXWLDVKAJEZDHFWJHKCHJHSONPXZMBARAQRDJKKCWVYTJUILVKXLUSSRGILNPXREQGLILVHYZKGWTTSFUIMTXYZOHXFHJNKCEHNNLKQVROJKUAHZXWEGNTIXKWXISINSJGILVKYZGCLVKTAIPPCRGMZESZGYDKHWCRIAKIVPBSYZDWKXRLNTSEVTEOCKKBIWGAPSRMASHICYYZAHAVVTMRSMDTLATTAZMMGAIGFGYJGSMTMNGTPGZKHMSHXRGHWOCAYBHZGCEIFDSRASWPMGYTQVFGWXHEIXGJGKIWEJWYPXKHUKVTIUUJXUGIKAJWTTQPFFCKHEDHAWOUXYXXGRSMVKXJKPPCRFJKQVROJLNTRKANKYJVVEDAYCXKAJGAIGFFJSTNSWMMWSLEEMJVKPGYPTMRSLROJHXTJVKWWJILRMFDRHXRGISTSJZZMLCWEKPJZGKIYXWWZWIEBXSIPWVBSONXGYMMWOCXVKFUZXSEHKEGCCZGIABXHLTQDEGEKBTFGAHVVNKODRDTPATVTIHHWYHIJHSWVGSTXXKVTVJHQVOTVGKTVARIJTSGAIGFFJATIIEWJVHNRFHSWSDWKTWEOTWKKDLUPZFBILNXWGKTTRTQANXLGHGFKYWFSMULNFITXYXDUGCXLLZSRACDTPWXTXIXFLVWCJBHSRACZFUGYHMSEJLNTCDTPWOIITHSGSXGREQQOBTFLXAHAIKAJQYWSFMIWYTVKXWKZWIELYSTSMEZFFJUMXAYATVMJXFUNHSCWNWXHMEWNNOSYREQQXPXZHSSRRSLKXWUUETMNGTPJKXWSRAFVVFMYTXYXHGYISWKZFTXRXBXKAGIKHGWGIPVTXLGHLZZMSYILVVTKZDJJMFQOCK
Klassiski test:
Sõne XYX kordub kuues kohas positsioonidel: 1, 190, 232, 631, 939, 1121.
XYXXWYXXLTYAUCWRLWWIPPCXITEEPRMTSTSEJONNOSPPTHLKSYGHSTERSIMJRNPZVTHGSBSETSVOCXVKJKZXRXNSVKGPPBSYRDKZVSGZXGVMMSZILVLTDJXIILFJKCSKFTLOKEKXILUGIKKJSZYYJMTJKKIEFFATACSRYZKXVITYAUCECTXKKHWDXSLUUXYXISTVIILTXHPXKEJSTSFPMMWOGWVEKATIIIXXLXPXYXWLNTCUBXUUKIITXGACHIXFKUCXFKZFGLEPUDJKPPZSNFMILRMBZGIMKFFCKHWVGXWLDVKAJEZDHFWJHKCHJHSONPXZMBARAQRDJKKCWVYTJUILVKXLUSSRGILNPXREQGLILVHYZKGWTTSFUIMTXYZOHXFHJNKCEHNNLKQVROJKUAHZXWEGNTIXKWXISINSJGILVKYZGCLVKTAIPPCRGMZESZGYDKHWCRIAKIVPBSYZDWKXRLNTSEVTEOCKKBIWGAPSRMASHICYYZAHAVVTMRSMDTLATTAZMMGAIGFGYJGSMTMNGTPGZKHMSHXRGHWOCAYBHZGCEIFDSRASWPMGYTQVFGWXHEIXGJGKIWEJWYPXKHUKVTIUUJXUGIKAJWTTQPFFCKHEDHAWOUXYXXGRSMVKXJKPPCRFJKQVROJLNTRKANKYJVVEDAYCXKAJGAIGFFJSTNSWMMWSLEEMJVKPGYPTMRSLROJHXTJVKWWJILRMFDRHXRGISTSJZZMLCWEKPJZGKIYXWWZWIEBXSIPWVBSONXGYMMWOCXVKFUZXSEHKEGCCZGIABXHLTQDEGEKBTFGAHVVNKODRDTPATVTIHHWYHIJHSWVGSTXXKVTVJHQVOTVGKTVARIJTSGAIGFFJATIIEWJVHNRFHSWSDWKTWEOTWKKDLUPZFBILNXWGKTTRTQANXLGHGFKYWFSMULNFITXYXDUGCXLLZSRACDTPWXTXIXFLVWCJBHSRACZFUGYHMSEJLNTCDTPWOIITHSGSXGREQQOBTFLXAHAIKAJQYWSFMIWYTVKXWKZWIELYSTSMEZFFJUMXAYATVMJXFUNHSCWNWXHMEWNNOSYREQQXPXZHSSRRSLKXWUUETMNGTPJKXWSRAFVVFMYTXYXHGYISWKZFTXRXBXKAGIKHGWGIPVTXLGHLZZMSYILVVTKZDJJMFQOCK
Positsioonide vahed on 189, 231, 630, 938, 1120
Et SÜT(189, 231, 630, 938, 1120)=7, siis võib oletada, et võtme pikkus m = 7.
Y1:XXWPPEPYSZSXRPKGLISEIYICVEWXIXFWIXCIHXEPLMWVHHXQWLSXLWMXEVHTSLLPSWVWSKPIAMAGMGXAESQEIXIIQEXMPVRVXGSEGLJLXJEIIWGXSCHEHRTISVVIGIRWWZWQGMXXCXCCMCIGTISVIMMMSMYXSEJFXSRIPLLJK
Y2:YLRCRJPGIVEVXPZVVIKKKJESICDYIKPVIYUIIFPZRKVKFJZRVVRRVTTFHRZIIVVCZCPKEKSCVDZFTZRYIWVIWKUKPDYVCRKVKFWEYRVRRZKYEVYVEZLKVDIJTJGJFEFKKFGAFUYLDIJZSDTRFKFKEEXJCERZLTKVYWXKVZVJ
Y3:XTLXMOTHMTTKNBVMLLFXKMFRTTXXLEMEXXBTXKUSMFGAWHMDYKGEHTXHNOXXNKKRGRBXVBRYVTMGMKGBFPFXEHUAFHXKROAEAFMMPOKMGZPXBBMKHGTBVTHHXHKTFWHTKBKNKLXLTXBFETHELAMXLZAXWWEHKMXVXKBHTZVM
Y4:XYWITNHSJHSJSSSMTFTIJTFYYXSITJMKXWXXFZDNBFXJJSBJTXIQYSYJNJWKSYTGYISRTIMYTLMYNHHHDMGGJUJJFAXXFJNDJJMJTJWFIMJWXSMFKIQTNPHSXQTSJJSWDITXYNDZPFHUJPSQXJIWYFYFNNQSXNWFHZXGXMTF
Y5:WAWTSNLTRGVKVYGSDJLLSJAZAKLSXSWALLUGKFJFZCWEHOAKJLLGZFZNLKEWJZAMDAYLEWAZMAGJGMWZSGWJWKXWCWGJJLKAGSWVMHWDSLZWSOWUEADFKAWWKVVGAVWELLTLWFUSWLSGLWGQAQWKSFAUWNQSWGSMGFKWLSKQ
Y6:YUIETOKENSOZKRZZJKOUZKTKUKUTHTOTXNUAUGKMGKLZKNRKUUNLKUOKKUGXGGIZKKZNOGSARTAGTSOGRYXGYVUTKORKKNYYATSKRXJRTCGZINOZGBEGOTYVVOAATHSOUNRGFIGRXVRYNOSOHYYZTJTNXOXRUTRYYTAGGYZO
Y7:XCPESSSRPBCXGDXIXCKGYKAXCHUVPSGIPTKCCLPIIHDDCPACISPIGIHCQANIICPEHIDTCAHHSTISPHCCATHKPTGTHUSPQTJCINLPSTIHSWKWPXCXCXGADVHGTTRIINDTPXTHSTCATWAHTIXBAWTWSUVHHSPRUPATIXGIHIDC
Kokkulangevus indeksid antud sõnede kohta:
Ic(Y1 ) = 0,0633; Ic(Y2 ) = 0,0661; Ic(Y3 ) = 0,0653; Ic(Y4 ) = 0,0659; Ic(Y5 ) = 0,0691; Ic(Y6 ) = 0,0656; Ic(Y7 ) = 0,0689
Tulemus annab kinnitust, et oletus m=7 peab paika.
Leiame omavahelise kokkulangevuse indeksid Ic(Yi,Yjg) kõigi nihkeväärtuste g=0…25 korral ja saame vastavad võrrandid:
k1-k2=13 mod(26) Võtmeks saame siit:
k1-k3=11mod(26) k1, k1+13, k1+15, k1+1, k1+14, k1+2, k1+11
k1-k4=25mod(26)
k1-k5=12(mod26)
k1-k6=24(mod26)
k1-k7=15(mod26)
k2-k3=24(mod26)
k2-k4=12(mod26)
k2-k5=25(mod26)
k2-k6=11(mod26)
k2-k7=2(mod26)
k3-k4=14(mod26)
k3-k5=1(mod26)
k3-k6=13(mod26)
k3-k7=4(mod26)
k4-k5=13(mod26)
k4-k6=25(mod26)
k4-k7=16(mod26)
k5-k6=12(mod26)
k5-k7=3(mod26)
k6-k7=17(mod26)
Peale katsetamist tuleb võtmesõnaks ERTFSGP ja dešrifreeritud tekst on järgmine:
THESE SITUATIONS AS RECALLED BY PLATO AND AS VIVIDLY ACTED UPON BY CORTEZ HAVE A COMMON AND INTERESTING UNDERLYING LOGIC NOTICE THAT THE SOLDIERS ARE NOT MOTIVATED TO RETREAT JUST OR EVEN MAINLY BY THEIR RATIONAL ASSESSMENT OF THE DANGERS OF BATTLE AND BY THEIR SELFINTEREST RATHER THEY DISCOVER A SOUND REASON TO RUN AWAY BY REALIZING THAT WHAT IT MAKES SENSE FOR THEM TO DO DEPENDS ON WHAT IT WILL MAKE SENSE FOR OTHERS TO DO AND THAT ALL OF THE OTHERS CAN NOTICE THIS TOO EVEN A QUITE BRAVE SOLDIER MAY PREFER TO RUN RATHER THAN HEROICALLY BUT POINTLESSLY DIE TRYING TO STEM THE ONCOMING TIDE ALL BY HIMSELF THUS WE COULD IMAGINE WITHOUT CONTRADICTION A CIRCUMSTANCE IN WHICH AN ARMY ALL OF WHOSE MEMBERS ARE BRAVE FLEES AT TOP SPEED BEFORE THE ENEMY MAKES A MOVE IF THE SOLDIERS REALLY ARE BRAVE THEN THIS SURELY ISNT THE OUTCOME ANY OF THEM WANTED EACH WOULD HAVE PREFERRED THAT ALL STAND AND FIGHT WHAT WE HAVE HERE THEN IS A CASE IN WHICH THE INTERACTION OF MANY INDIVIDUALLY RATIONAL DECISIONMAKING PROCESSES ONE PROCESS PER SOLDIER PRODUCES AN OUTCOME INTENDED BY NOONE MOST ARMIES TRY TO AVOID THIS PROBLEM JUST AS CORTEZ DID SINCE THEY CANT USUALLY MAKE RETREAT PHYSICALLY IMPOSSIBLE THEY MAKE IT ECONOMICALLY IMPOSSIBLE THEY SHOOT DESERTERS THEN STANDING AND FIGHTING IS EACH SOLDIERS INDIVIDUALLY RATIONAL COURSE OF ACTION AFTER ALL BECAUSE THE COST OF RUNNING IS SURE TO BE AT LEAST AS HIGH AS THE COST OF STAYING