commit 22b472e79b357ade3e889f379b32eceff52dfac7 Author: Jip J. Dekker Date: Wed Apr 11 21:33:40 2018 +1000 Add initial version of the cypher tool diff --git a/crypt.html b/crypt.html new file mode 100644 index 0000000..c1ecdcd --- /dev/null +++ b/crypt.html @@ -0,0 +1,253 @@ + + + + + + + + + + + Monoalphabetic substitution + + + +

Monoalphabetic substitution

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Plain Text

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Encrypted Text

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+ A +

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+ B +

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+ C +

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+ D +

+ +

+ E +

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+ F +

+ +

+ G +

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+ H +

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+ I +

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+ J +

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+ K +

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+ L +

+ +

+ M +

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+ N +

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+ O +

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+ P +

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+ Q +

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+ R +

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+ S +

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+ T +

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+ U +

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+ V +

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+ W +

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+ X +

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+ Y +

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+ Z +

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+ + + + + + + + + diff --git a/crypt.js b/crypt.js new file mode 100644 index 0000000..d7d08a1 --- /dev/null +++ b/crypt.js @@ -0,0 +1,96 @@ +function get_key() { + var map = []; + for (let i = 0; i < 26; i++) { + map.push($("#" +String.fromCharCode(i + 65)).val()); + } + + for (let i = 0; i < map.length; i++) { + if (!(typeof map[i] === 'string' || map[i] instanceof String) || map[i].length < 1) { + map[i] = String.fromCharCode(i + 65); + } else { + const code = map[i].charCodeAt(0); + if (map[i].length > 1) { + map[i] = map[i][0]; + $("#" +String.fromCharCode(i + 65)).val(map[i][0]); + } else if (code >= 65 && code <= 90) { + map[i] = String.fromCharCode(code + 32); + } + } + } + + return map; +} + +function encrypt(plaintext, key) { + var encrypted = ""; + + var text = plaintext.toUpperCase(); + for (let i = 0; i < text.length; i++) { + const code = text.charCodeAt(i); + if (code >= 65 && code <= 90) { + encrypted += key[code - 65]; + } else { + encrypted += text[i]; + } + } + + return encrypted; +} + +function decrypt(encrypted, key) { + var plaintext = ""; + + var text = encrypted.toLowerCase() + for (let i = 0; i < text.length; i++) { + var loc = key.indexOf(text[i]); + const code = text.charCodeAt(i); + if (loc >= 0) { + plaintext += String.fromCharCode(loc + 97); + } else if (97 <= code && code <= 122) { + plaintext += String.fromCharCode(code - 32); + } else { + plaintext += text[i]; + } + } + + return plaintext; +} + +$(document).ready(function() { + $("#encrypt").button().click(function(){ + var key = get_key(); + var text = $("#plain-text").val(); + $("plain-text").val(text.toLowerCase()); + var encrypted = encrypt(text, key); + $("#encrypted-text").val(encrypted); + }); + $("#decrypt").button().click(function(){ + var key = get_key(); + var text = $("#encrypted-text").val(); + $("#encrypted-text").val(text.toLowerCase()); + var decrypted = decrypt(text, key); + $("#plain-text").val(decrypted); + }); + $("#generate-alpha").button().click(function(){ + var key = get_key(); + var alpha = ""; + for (let i = 0; i < key.length; i++) { + alpha += key[i]; + } + $("#alphabet").val(alpha); + }); + $("#import-alpha").button().click(function(){ + var alpha = $("#alphabet").val(); + if (alpha.length != 26) { + alert("Alphabet of invalid length"); + return; + } + alpha = alpha.toUpperCase(); + for (let i = 0; i < alpha.length; i++) { + const code = alpha.charCodeAt(i); + if (code != i + 65) { + $("#" +String.fromCharCode(i + 65)).val(alpha[i]); + } + } + }); +});