Using CPA4 to crack the classic cipher algorithm

Here is a cipher encrypted by the classic cipher algorithm (the encryption algorithm is unknown):

Yvvnerujjvnywhbdvkpchfgvjtzwqsuporqfzpoekkjgziicdwwkeejdsruef

Whwseyejejhnaeepjbjwnuztavjswrthswlcdxqrnoclsodkrrfjtfhlfznbx

Wyvdwdcwyzqlqrnevuiiienxzmwtdsyhgstwmvznrvhyihhcxjijhiojphvjw

Srpejwnhrhirqbcdwnzqmwjpoibnbjdeshloewcfdhvzjgtdwsvntydyweyll

Gjrrohfuyplppzrssvniejxhzjtrwyvvdecpttrieevhzlxsvunstovzwjfsa

Svlsgzjcvwmseioidhsywsddisrjadhkcideivjzwwsfqjcwphvwtdtkatkjg

Zjwfpjbjbofwgochaegfhmyodpjbkwtfukcixokkrseoaegbcdanjitckxaco

Xvvdajdqgfxetrrskdewlwgketronoesoddshfxezqiitpeulshfdeiftiepr

Pvkcfpbroqwechroqcwbadhfbuwlcwmokshzojkfnkzqlojhanbjfzjhvuxdr

Neklrskdezqiswwtzjfpcamfufqvolrwjgkreewzfvesrvftzbauhasckpdhs

Hzjskuzqkkrydawecjlvyqfjdlfysuwcfxwgvhajwbsvgbvwbsvjaegtqkkbv

Ufhkdezufbzwnwrthswlcdhouamplshvdrrqyvvnejkjhiwiehiwiwnzdskfi

Eershyatvfmbzyacdxdvytjrkqfwcylsunkmvqxtfktsdqzektaxxhwkokefz

Cxukvustefzffzcuwfpjbjbofwgochwyrjjvnsrbxhywtkkjavjsxdrsrjdkk

Jkfieevlodaaihyvvoadhmojylvdwzpjemhwkfnkvgnbrlrfijgjeoedqseri

Irsavjtjkjhfhdwlkotkmrvritdajztavjswrthswlckfgxnonqtjvntyhqoj

Pfvzistwdvvnhywsewgstkmvdsmdkrvvnazhaiwthyamvqxurienrrsewrvsm

Mjecroqmuefwhwseptfpjbrjdkkjafnekkjkfieevlodadvyjzflskkjafnez

Wngwqlcrkggaczinqzpivvyvrprvtzwiaaulktvneewfdgnorfmtikmrftotd

Jlvyzzgejddwerocojmswlcrwprokvwgochtyhwsjjogrnbkenxutigenxlyo

Chuegjfkdejdrstwtvjtfpphvrgjzkujsmmjecroiwwbeihsqvoaihtbcutyh

Xhrntzqldfenkwmswkrdhwgknibhwocoogrnbkotfnjmkwcklhocziwijfvjc

Vvfbuprrlswecmvwmcuotrnjomarpvnaghevafaghekkjdzcgplshyamzgizv

Zrzoqgjdetrshzjuvgdclnedraskdakiwcdwmvqxhiwielsujasjltbrjdprz

Fvhojwbvvnervlsearroqmjlernnbxbeddqsghaphwguknkwjbupotdwsrxol

Wyvzokzqicwyodsjhzpimhssjoiedboiiugptfryeyrusjphrwismalfsrsep

Ielywrpimhxzzgekkjkfieevkcfpbroqqfwcylsutkuivjwepeyufbnditkbo

Jwtkhsrvzbpztavjoeodkzhlyhqdkknruwcnphvjfdsatnhjbkdefsucipuel

Ywvoawitfuadkrrocaaegksdwlvftotdejrkqfqrjhdcldamhlfvwttrfqyas

Kkfhljdvuxhrjdkkjkfieevlodalznjoepoeltqrxrzqnweetrodcilhzondg

Abvulsikozqkfrjcvvfwuioidhssqtnkfhjprznjgdaijzmseoodhysrisfuh

Zlxstktcjahvdiqfwcyhxbfpbrvjrfjaivzafneosjfzanthgikkncbgstwuj

Hyvvuhrsuseposhrsewszvfwuxewrwskdexdrszodziksiankdsrkdakvhzvw

Rkrjjvnyfqjplptyhtdgkrkxswkeejdktfndvgyctkatkjgjdoloibkxeulkt

Vneewtdgkrkxswkeejitfrhlkkjufopvoyvrpmfufqvesgujotdiejnggwrkl

Hicwrcbaocqasojwephvpnruhevdxhndeihqokalpztavjswrthswlckfgdwd

Vgwodwtzfxhiedvvnfrjffujlripchkwvhdjztavjsedywfjacwjodofirroc

Hcrwjufnivvxhrntzqlokqaegnhjjakltbrhlvdlivberwzfvotvdrgzjtyhk

Wiotulawjeoedsrrjokkjfwevvlshyasvftbuzimlxwfjnfwycdankltbrpok

Dqtlpsroysrisjswsrzatutgjboluiwwbeihshcaaxxjrzrijltbjwtwlwgkc

Lrqhszpsvdxmwkrnhxhvnnjwthvjdkryvzjkkkfhkdijlxotkmgojhvhyulkt

Vneewhicpuihgikdoehxhcuajdswkwlzdskywtjwwitgmvwmsdkskzjfvphvv

Nazhailywvosrliafnathusfllvdwsnwrddsrrlpirfqywbchfbuphvujgekp

Cdhsndeihyvrpijdxqcaaidxwebofwgochwydywjavzgjbkpodhnbkahidswj

Wgzjfbkecgdxgzknwrwtfktsdqzrhemhqcwenkhwsjptydygknucbtikotrqi

Wecsghhwwecroqmrioejyvvsodhshykuxknhjylvdwhywtkknggwsjltbtwri

Ljgrlokhshzwlnknqyesfqqmekwshnbxqnkdudvzhfsjtlhlpwmwjyoluxszo

Aelrdfntrqygkapkrboizskkngdwhuljafdadpfrbdaelfavibvuttkdezufb

Zwnwdxkfieevhcdiikwjswqlcbfuiaejznhyphvitfdarzwfzpwnuffbrzatr

Fqysodhsgwkokefzcdajiqclnijkjrzjrvfjbkueruxoeznfzfrruszwxhyam

Fvydflucdwggkrkdrceciidswrjwfpjbjdejdnrzpsroxcfjefiyvvbamrzfz

Pejstfkoffurijhidztavjbvffijatyhdoiaacotkvztfsqopshzojkvwrzql

Oyaauvhoibmfkfadwdbkfbzwljrgsceemhxhywttrrpzjakltbfbdvyjzflmv

Qyqfqrjhxoezeclystkmghywkeoevqwbanvaymvwrjintrqwfpjbjsoioiwef

Oigfbkdewlwgksodhsgnkrcghigdecgnbkdedlircaervyoiatyhbopboizff

Uboiwmsiagzrswkoaxujokkpgrwhljikbycrptidhhgqbclhcgenzrshfsodh

Sgwkokefzcwnudqgfboiijarhedlircaervysijtvdrgkksyrbhyaiivyfvjg

Kkxoxwievywepeiqfhzknrotdgknvqygjdetrsqcqdvg

Cracking process:

1. First determine whether it is single table or multi-table encryption, by counting the letter frequency

Copy the ciphertext to ciphertext, click on the left Freq, there is the function of counting the letter frequency.

Statistical results:

A 120 0.034

B 91 0.026

C 105 0.030

D 178 0.051

E 178 0.051

F 164 0.047

G 99 0.028

H 180 0.051

I 148 0.042

J 205 0.058

K 201 0.057

L 111 0.032

M 55 0.016

N 113 0.032

O 146 0.041

P 85 0.024

Q 82 0.023

R 193 0.055

S 168 0.048

T 139 0.039

U 87 0.025

V 177 0.050

W 210 0.060

X 63 0.018

Y 97 0.028

Z 126 0.036

You can choose to display it in the form of a chart:

can see the letter frequency distribution of the more average, no character probability is very high or low probability, so guess this is a multi-table encryption cipher. (Because single-table encryption usually shows the language's characteristics)

Now that the multi-table encryption is known, what kind of multi-table encryption algorithm?

The actual approach can only be tried.

First, assume that this is a ciphertext encrypted by the Vigenere cipher algorithm:

To determine the length of the key first

Using The Kasiski of the CAP, I learned

String Distance

YVV 273

YVV 707

YVV 868

YVV 1953

YVV 2765

YVV 3101

Distance to YVV: 434 595 1680 2492 2828

Greatest common Divisor is 7 .

Guess the length of the key is 7

Then use the low Freq of the CAP .

Enter the length of the key 7, the possible key given is forward.

Using the vigenere Cipherof the CAP , input keyword:forward, the original text is

There is very few people as entitledtoanalysethesimilaritiesanddif
Ferencesbetweenmensandwomensfootballascarolinamoracefollowing
Ayearplayingcareerduringwhichshebecamewidelyrecognisedasthegr
Eatestitalianwomaninhistoryinshebeganacoachingcareerthatinclu
Dedashortbutpioneeringstintatthehelmofamensclubseriecsviterbe
Seinsincethenmoracehasmadeanameforherselfasoneofthetopcoaches
Inwomensfootballandatvcommentatorforbothmensandwomensfootball
Shehasalsobecomethefirstitalianwomantobeinductedintohercountr
Ysfootballinghalloffameandallthatwhileworkingaslawyerinherspa
Retimetheindefatigablemoraceslatestventureisasafifadevelopmen
Tinstructorhavingjustconductedacourselastweekbetweenandoctobe
Rattheiranianfootballacademyintehranthereshetrainediranianwom
Enonthetechnicalaspectsofcoachingwomensfootballnotjustfootbal
Lbutspecificallywomensfootballwhoeversaysthatthemensgameandth
Ewomensgamearethesamehasclearlyneverworkedinaprofessionalenvi
Ronmentshetoldfifacomasmuchaswomensfootballhasgrownoverthelas
Tfewdecadesithasntbecomeanymoresimilartothemensgamewomenareph
Ysicallydifferenttomenandthemorethewomensgamedevelopsthemorei
Tisfullofspecificitiesthatrequireadifferentapproachfromacoach
Justlikesayinvolleyballorbasketballtheresnopointingroupingita
Llunderthesamecategorytheobviousphysicaldifferencesareonlythe
Startingpointtheformerstrikeralsopointstokeytacticaldifferenc
Esandtrainingmethodstakeaverysimpleexamplethepiggyinthemiddle
Drillsshecontinuedyouremovethatfromamenstrainingsessionandyou
Relostwhereasgenerallyspeakingfemaleplayersdonttendtocareabou
Tthiskindofcompetitivenessinawarmupmoracehopesthatdevelopment
Initiativeslikethewomensfootballcoachingcourseintehranwhichwa
Sattendedbywomenonlywillhelptonarrowthegapbetweentheopportuni
Tiesaffordedtomaleandfemalecoachesofcourseyouhavegreatcoaches
Thatunderstandthewomensgamelikeantoniocabriniinitalyorphilipp
Ebergerooinfrancesaidmoracebutwhatstrikesmeiswhensometeamsorc
Lubschooseheadcoachesnotbasedonarsumorexperiencebutonlybecaus
Etheyhappentobemenasisaidbeforethegameisdifferentandthatsclea
Rtoeveryonebuttheopportunitiesaffordedtocoachesshouldntbediff
Erentopportunitiesforallthegospelthatmoraceispreachingisparti
Cularlyvaluableinthemiddleeastwherelatelywomensfootballhasmad
Edramaticstridesiranforexamplefieldswomensnationalteamsfromal
Lcategoriesstartingatuanditsnationalleaguefeaturesteamsinthef
Irstdivisionandanotherfiveintheseconddivisionnottomentionatot
Alfutsalteamsspreadacrossfourdifferentleaguedivisionsatfirstg
Lanceitseasyforwesternstotendtothinkthatthisisacompletelydiff
Erentculturebuthonestlyasanitalianwhatstruckmethemostwerethes
Imilaritiessaidmoracepeoplearewarmandapproachableandtheresnop
Lacewherethatisasclearasinfootballwhatisevidenttomeintehranis
Agiganticpassionforfootballalevelofinterestthatstrulyoutstand
Ingspecificallyamongthewomenthoughitsclearthatthispassioncarr
Iesapotentialwhichisonlynowbeinguntappedhopefullythiscourseis
Animportantsteptowardsthismahdiemohammadkhaniamemberoftheiran
Ianfaswomenscommitteefullyagreeswiththeformeritalyandcanadaco
Achwomensfootballhasflourishedinrecentyearsandnowadaysitsthem
Ostpopularsportamongiranianwomenshesaiditsalsooneofthefavouri
Tesportsformuslimwomenbecausetheyareallowedtoplaywhilewearing
Aheadscarfmohammadkhanialsobelievesthatcombinationofdevelopme
Ntcoursesandelitecompetitionslikenextyearsfifauwomensworldinj
Ordanthefirstwomensworldcupheldinthemiddleeastarethewayforwar
Dfortheregionitsagreatopportunitytoattractpublicopiniontowome
Nsfootballandalsoforfemalemiddleeasternteamstoshowtheirstreng
thsagainstinternationalopponentssheconcluded

If the translation is found to be meaningful, the ciphertext is cracked.

If the translation is found to be meaningless, it is necessary to assume a different encryption algorithm and use the corresponding decryption method according to the assumed algorithm.

Using CPA4 to crack the classic cipher algorithm