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Vigenère cipher/Cryptanalysis: Difference between revisions
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THISWASTHEPOEMTHATALICEREADJABBERWOCKYTWASBRILLIGANDTHESLITHYTOVESDIDGYREANDGIMBLEINTHEWABEALLMIMSYWERETHEBOROGOVESANDTHEMOMERATHSOUTGRABEBEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCHBEWARETHEJUBJUBBIRDANDSHUNTHEFRUMIOUSBANDERSNATCHHETOOKHISVORPALSWORDINHANDLONGTIMETHEMANXOMEFOEHESOUGHTSORESTEDHEBYTHETUMTUMTREEANDSTOODAWHILEINTHOUGHTANDASINUFFISHTHOUGHTHESTOODTHEJABBERWOCKWITHEYESOFFLAMECAMEWHIFFLINGTHROUGHTHETULGEYWOODANDBURBLEDASITCAMEONETWOONETWOANDTHROUGHANDTHROUGHTHEVORPALBLADEWENTSNICKERSNACKHELEFTITDEADANDWITHITSHEADHEWENTGALUMPHINGBACKANDHASTTHOUSLAINTHEJABBERWOCKCOMETOMYARMSMYBEAMISHBOYOFRABJOUSDAYCALLOOHCALLAYHECHORTLEDINHISJOYTWASBRILLIGANDTHESLITHYTOVESDIDGYREANDGIMBLEINTHEWABEALLMIMSYWERETHEBOROGOVESANDTHEMOMERATHSOUTGRABEITSEEMSVERYPRETTYSHESAIDWHENSHEHADFINISHEDITBUTITSRATHERHARDTOUNDERSTAND
</pre>
=={{header|Nim}}==
{{trans|Julia}}
{{trans|Phix}}
This is a translation of Julia algorithm with some ideas from Phix translation.
<lang Nim>import sequtils, strutils, sugar, tables, times
const
CipherText = """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""".splitWhitespace.join()
FreqLetters = {'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}.toTable
FreqDigraphs = {"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}.toTable
FreqTrigraphs = {"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}.toTable
func decrypt(enc, key: string): string =
let encLen = enc.len
let keyLen = key.len
result.setLen(encLen)
var k = 0
for i in 0..<encLen:
result[i] = chr((ord(enc[i]) - ord(key[k]) + 26) mod 26 + ord('A'))
k = (k + 1) mod keyLen
func cryptanalyze(enc: string; maxKeyLen = 20): tuple[maxKey, maxDec: string] =
let encLen = enc.len
var maxScore = 0.0
for keyLen in 1..maxKeyLen:
var key = newString(keyLen)
var idx = collect(newSeq):
for i in 1..encLen:
if i mod keyLen == 0:
i - keyLen
for i in 0..<keyLen:
var maxSubscore = 0.0
for j in 'A'..'Z':
var subscore = 0.0
let encidx = idx.mapIt(enc[it]).join()
for k in decrypt(encidx, $j):
subscore += FreqLetters[k]
if subscore > maxSubscore:
maxSubscore = subscore
key[i] = j
for item in idx.mitems: inc item
let dec = decrypt(enc, key)
var score = 0.0
for i in dec:
score += FreqLetters[i]
for i in 0..(encLen - 3):
let digraph = dec[i..(i+1)]
let trigraph = dec[i..(i+2)]
score += 2 * FreqDigraphs.getOrDefault(digraph)
score += 3 * FreqTrigraphs.getOrDefault(trigraph)
if score > maxScore:
maxScore = score
result.maxKey = key
result.maxDec = dec
let t0 = cpuTime()
let (key, dec) = CipherText.cryptanalyze()
echo "key: ", key, '\n'
echo dec, '\n'
echo "Elapsed time: ", (cpuTime() - t0).formatFloat(ffDecimal, precision = 3), " s"</lang>
{{out}}
<pre>key: THECHESHIRECAT
THISWASTHEPOEMTHATALICEREADJABBERWOCKYTWASBRILLIGANDTHESLITHYTOVESDIDGYREANDGIMBLEINTHEWABEALLMIMSYWERETHEBOROGOVESANDTHEMOMERATHSOUTGRABEBEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCHBEWARETHEJUBJUBBIRDANDSHUNTHEFRUMIOUSBANDERSNATCHHETOOKHISVORPALSWORDINHANDLONGTIMETHEMANXOMEFOEHESOUGHTSORESTEDHEBYTHETUMTUMTREEANDSTOODAWHILEINTHOUGHTANDASINUFFISHTHOUGHTHESTOODTHEJABBERWOCKWITHEYESOFFLAMECAMEWHIFFLINGTHROUGHTHETULGEYWOODANDBURBLEDASITCAMEONETWOONETWOANDTHROUGHANDTHROUGHTHEVORPALBLADEWENTSNICKERSNACKHELEFTITDEADANDWITHITSHEADHEWENTGALUMPHINGBACKANDHASTTHOUSLAINTHEJABBERWOCKCOMETOMYARMSMYBEAMISHBOYOFRABJOUSDAYCALLOOHCALLAYHECHORTLEDINHISJOYTWASBRILLIGANDTHESLITHYTOVESDIDGYREANDGIMBLEINTHEWABEALLMIMSYWERETHEBOROGOVESANDTHEMOMERATHSOUTGRABEITSEEMSVERYPRETTYSHESAIDWHENSHEHADFINISHEDITBUTITSRATHERHARDTOUNDERSTAND
Elapsed time: 0.041 s</pre>
=={{header|OCaml}}==
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