106 lines
3.4 KiB
Plaintext
106 lines
3.4 KiB
Plaintext
import "./math" for Nums
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import "./iterate" for Stepped
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import "./str" for Char, Str
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import "./fmt" for Fmt
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var encoded =
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"MOMUD EKAPV TQEFM OEVHP AJMII CDCTI FGYAG JSPXY ALUYM NSMYH" +
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"VUXJE LEPXJ FXGCM JHKDZ RYICU HYPUS PGIGM OIYHF WHTCQ KMLRD" +
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"ITLXZ LJFVQ GHOLW CUHLO MDSOE KTALU VYLNZ RFGBX PHVGA LWQIS" +
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"FGRPH JOOFW GUBYI LAPLA LCAFA AMKLG CETDW VOELJ IKGJB XPHVG" +
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"ALWQC SNWBU BYHCU HKOCE XJEYK BQKVY KIIEH GRLGH XEOLW AWFOJ" +
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"ILOVV RHPKD WIHKN ATUHN VRYAQ DIVHX FHRZV QWMWV LGSHN NLVZS" +
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"JLAKI FHXUF XJLXM TBLQV RXXHR FZXGV LRAJI EXPRV OSMNP KEPDT" +
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"LPRWM JAZPK LQUZA ALGZX GVLKL GJTUI ITDSU REZXJ ERXZS HMPST" +
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"MTEOE PAPJH SMFNB YVQUZ AALGA YDNMP AQOWT UHDBV TSMUE UIMVH" +
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"QGVRW AEFSP EMPVE PKXZY WLKJA GWALT VYYOB YIXOK IHPDS EVLEV" +
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"RVSGB JOGYW FHKBL GLXYA MVKIS KIEHY IMAPX UOISK PVAGN MZHPW" +
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"TTZPV XFCCD TUHJH WLAPF YULTB UXJLN SIJVV YOVDJ SOLXG TGRVO" +
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"SFRII CTMKO JFCQF KTINQ BWVHG TENLH HOGCS PSFPV GJOKM SIFPR" +
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"ZPAAS ATPTZ FTPPD PORRF TAXZP KALQA WMIUD BWNCT LEFKO ZQDLX" +
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"BUXJL ASIMR PNMBF ZCYLV WAPVF QRHZV ZGZEF KBYIO OFXYE VOWGB" +
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"BXVCB XBAWG LQKCM ICRRX MACUO IKHQU AJEGL OIJHH XPVZW JEWBA" +
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"FWAML ZZRXJ EKAHV FASMU LVVUT TGK"
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var freq = [
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0.08167, 0.01492, 0.02782, 0.04253, 0.12702, 0.02228, 0.02015,
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0.06094, 0.06966, 0.00153, 0.00772, 0.04025, 0.02406, 0.06749,
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0.07507, 0.01929, 0.00095, 0.05987, 0.06327, 0.09056, 0.02758,
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0.00978, 0.02360, 0.00150, 0.01974, 0.00074
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]
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var bestMatch = Fn.new { |a|
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var sum = Nums.sum(a)
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var bestFit = 1e100
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var bestRotate = 0
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for (rotate in 0..25) {
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var fit = 0
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for (i in 0..25) {
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var d = a[(i + rotate) % 26] / sum - freq[i]
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fit = fit + d * d / freq[i]
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}
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if (fit < bestFit) {
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bestFit = fit
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bestRotate = rotate
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}
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}
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return bestRotate
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}
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var freqEveryNth = Fn.new { |msg, key|
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var len = msg.count
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var interval = key.count
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var out = List.filled(26, 0)
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var accu = List.filled(26, 0)
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for (j in 0...interval) {
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for (i in 0..25) out[i] = 0
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for (i in Stepped.new(j...len, interval)) out[msg[i]] = out[msg[i]] + 1
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var rot = bestMatch.call(out)
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key[j] = Char.fromCode(rot + 65)
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for (i in 0..25) accu[i] = accu[i] + out[(i + rot) % 26]
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}
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var sum = Nums.sum(accu)
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var ret = 0
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for (i in 0..25) {
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var d = accu[i] / sum - freq[i]
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ret = ret + d * d / freq[i]
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}
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return ret
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}
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var decrypt = Fn.new { |text, key|
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var sb = ""
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var ki = 0
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for (c in text) {
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if (Char.isAsciiUpper(c)) {
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var ci = (c.bytes[0] - key[ki].bytes[0] + 26) % 26
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sb = sb + Char.fromCode(ci + 65)
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ki = (ki + 1) % key.count
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}
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}
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return sb
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}
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var enc = encoded.replace(" ", "")
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var txt = List.filled(enc.count, 0)
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for (i in 0...txt.count) txt[i] = Char.code(enc[i]) - 65
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var bestFit = 1e100
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var bestKey = ""
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var f = "$f $2d $s"
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System.print(" Fit Length Key")
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for (j in 1..26) {
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var key = List.filled(j, "")
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var fit = freqEveryNth.call(txt, key)
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var sKey = key.join("")
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Fmt.write(f, fit, j, sKey)
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if (fit < bestFit) {
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bestFit = fit
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bestKey = sKey
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System.write(" <--- best so far")
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}
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System.print()
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}
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System.print()
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System.print("Best key : %(bestKey)")
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System.print("\nDecrypted text:\n%(decrypt.call(enc, bestKey))")
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