Vigenère cipher/Cryptanalysis: Difference between revisions

=={{header|Phix}}==

{{trans|Julia}}

<lang Phix>atom t0 = time()

constant ciphertext = substitute_all("""

MOMUD EKAPV TQEFM OEVHP AJMII CDCTI FGYAG JSPXY ALUYM NSMYH

VUXJE LEPXJ FXGCM JHKDZ RYICU HYPUS PGIGM OIYHF WHTCQ KMLRD

ITLXZ LJFVQ GHOLW CUHLO MDSOE KTALU VYLNZ RFGBX PHVGA LWQIS

FGRPH JOOFW GUBYI LAPLA LCAFA AMKLG CETDW VOELJ IKGJB XPHVG

ALWQC SNWBU BYHCU HKOCE XJEYK BQKVY KIIEH GRLGH XEOLW AWFOJ

ILOVV RHPKD WIHKN ATUHN VRYAQ DIVHX FHRZV QWMWV LGSHN NLVZS

JLAKI FHXUF XJLXM TBLQV RXXHR FZXGV LRAJI EXPRV OSMNP KEPDT

LPRWM JAZPK LQUZA ALGZX GVLKL GJTUI ITDSU REZXJ ERXZS HMPST

MTEOE PAPJH SMFNB YVQUZ AALGA YDNMP AQOWT UHDBV TSMUE UIMVH

QGVRW AEFSP EMPVE PKXZY WLKJA GWALT VYYOB YIXOK IHPDS EVLEV

RVSGB JOGYW FHKBL GLXYA MVKIS KIEHY IMAPX UOISK PVAGN MZHPW

TTZPV XFCCD TUHJH WLAPF YULTB UXJLN SIJVV YOVDJ SOLXG TGRVO

SFRII CTMKO JFCQF KTINQ BWVHG TENLH HOGCS PSFPV GJOKM SIFPR

ZPAAS ATPTZ FTPPD PORRF TAXZP KALQA WMIUD BWNCT LEFKO ZQDLX

BUXJL ASIMR PNMBF ZCYLV WAPVF QRHZV ZGZEF KBYIO OFXYE VOWGB

BXVCB XBAWG LQKCM ICRRX MACUO IKHQU AJEGL OIJHH XPVZW JEWBA

FWAML ZZRXJ EKAHV FASMU LVVUT TGK""",{" ","\n"},{"",""})

constant letters = new_dict(

{{'E',12.702},

{'T',9.056},

{'A',8.167},

{'O',7.507},

{'I',6.966},

{'N',6.749},

{'S',6.327},

{'H',6.094},

{'R',5.987},

{'D',4.253},

{'L',4.025},

{'C',2.782},

{'U',2.758},

{'M',2.406},

{'W',2.361},

{'F',2.228},

{'G',2.015},

{'Y',1.974},

{'P',1.929},

{'B',1.492},

{'V',0.978},

{'K',0.772},

{'J',0.153},

{'X',0.150},

{'Q',0.095},

{'Z',0.074}})

constant digraphs = new_dict(

{{"TH",15.2},

{"HE",12.8},

{"IN",9.4},

{"ER",9.4},

{"AN",8.2},

{"RE",6.8},

{"ND",6.3},

{"AT",5.9},

{"ON",5.7},

{"NT",5.6},

{"HA",5.6},

{"ES",5.6},

{"ST",5.5},

{"EN",5.5},

{"ED",5.3},

{"TO",5.2},

{"IT",5.0},

{"OU",5.0},

{"EA",4.7},

{"HI",4.6},

{"IS",4.6},

{"OR",4.3},

{"TI",3.4},

{"AS",3.3},

{"TE",2.7},

{"ET",1.9},

{"NG",1.8},

{"OF",1.6},

{"AL",0.9},

{"DE",0.9},

{"SE",0.8},

{"LE",0.8},

{"SA",0.6},

{"SI",0.5},

{"AR",0.4},

{"VE",0.4},

{"RA",0.4},

{"LD",0.2},

{"UR",0.2}})

constant trigraphs = new_dict(

{{"THE",18.1},

{"AND",7.3},

{"ING",7.2},

{"ION",4.2},

{"ENT",4.2},

{"HER",3.6},

{"FOR",3.4},

{"THA",3.3},

{"NTH",3.3},

{"INT",3.2},

{"TIO",3.1},

{"ERE",3.1},

{"TER",3.0},

{"EST",2.8},

{"ERS",2.8},

{"HAT",2.6},

{"ATI",2.6},

{"ATE",2.5},

{"ALL",2.5},

{"VER",2.4},

{"HIS",2.4},

{"HES",2.4},

{"ETH",2.4},

{"OFT",2.2},

{"STH",2.1},

{"RES",2.1},

{"OTH",2.1},

{"ITH",2.1},

{"FTH",2.1},

{"ONT",2.0}})

function decrypt(string enc, string key)

integer keylen = length(key), k = 1

string msg = repeat(' ', length(enc))

for i=1 to length(enc) do

msg[i] = mod(enc[i]-key[k]+26,26)+'A'

k = mod(k,keylen)+1

end for

return msg

end function

function cryptanalyze(string enc, integer maxkeylen=20)

integer enclen = length(enc)

string maxkey = "",

maxdec = "",

k1 = " "

atom maxscore = 0.0

for keylen=1 to maxkeylen do

string key = repeat(' ',keylen)

sequence idx = {}

for i=1 to enclen do

if mod(i,keylen)=0 then

idx &= i-keylen+1

end if

end for

for i=1 to keylen do

atom maxsubscore = 0.0

for j='A' to 'Z' do

atom subscore = 0.0

k1[1] = j

string encidx = ""

for ii=1 to length(idx) do

encidx &= enc[idx[ii]]

end for

string dec = decrypt(encidx,k1)

for di=1 to length(dec) do

subscore += getd(dec[di],letters)

end for

if subscore > maxsubscore then

maxsubscore = subscore

key[i] = j

end if

end for

idx = sq_add(idx,1)

end for

string dec = decrypt(enc, key)

atom score = 0.0

for i=1 to length(dec) do

score += getd(dec[i],letters)

end for

for i=1 to enclen - 2 do

string digraph = dec[i..i+1]

string trigraph = dec[i..i + 2]

score += 2 * getd(digraph,digraphs)

score += 3 * getd(trigraph,trigraphs)

end for

if score > maxscore then

maxscore = score

maxkey = key

maxdec = dec

end if

end for

return {maxkey,maxdec}

end function

function fold(string s, integer w)

for i=1 to length(s) by w do

s[i..i-1] = "\n"

end for

return s

end function

string {key, dec} = cryptanalyze(ciphertext)

printf(1,"key: %s\n\n%s\n\n", {key, fold(dec,80)})

printf(1,"elapsed time: %3.2f seconds",{time()-t0})</lang>

{{Out}}

<pre>

key: THECHESHIRECAT

THISWASTHEPOEMTHATALICEREADJABBERWOCKYTWASBRILLIGANDTHESLITHYTOVESDIDGYREANDGIM

BLEINTHEWABEALLMIMSYWERETHEBOROGOVESANDTHEMOMERATHSOUTGRABEBEWARETHEJABBERWOCKM

YSONTHEJAWSTHATBITETHECLAWSTHATCATCHBEWARETHEJUBJUBBIRDANDSHUNTHEFRUMIOUSBANDER

SNATCHHETOOKHISVORPALSWORDINHANDLONGTIMETHEMANXOMEFOEHESOUGHTSORESTEDHEBYTHETUM

TUMTREEANDSTOODAWHILEINTHOUGHTANDASINUFFISHTHOUGHTHESTOODTHEJABBERWOCKWITHEYESO

FFLAMECAMEWHIFFLINGTHROUGHTHETULGEYWOODANDBURBLEDASITCAMEONETWOONETWOANDTHROUGH

ANDTHROUGHTHEVORPALBLADEWENTSNICKERSNACKHELEFTITDEADANDWITHITSHEADHEWENTGALUMPH

INGBACKANDHASTTHOUSLAINTHEJABBERWOCKCOMETOMYARMSMYBEAMISHBOYOFRABJOUSDAYCALLOOH

CALLAYHECHORTLEDINHISJOYTWASBRILLIGANDTHESLITHYTOVESDIDGYREANDGIMBLEINTHEWABEAL

LMIMSYWERETHEBOROGOVESANDTHEMOMERATHSOUTGRABEITSEEMSVERYPRETTYSHESAIDWHENSHEHAD

FINISHEDITBUTITSRATHERHARDTOUNDERSTAND

elapsed time: 0.42 seconds

</pre>