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A very simple cryptography JavaScript module created for my xmas calendar 2013.
var encryption = function() {
// Works with ASCII chars from 32 (space)
// to 248 (å).
var shiftCharCode = function(code, shift) {
if (shift < 0) shift += (248 - 32 + 1)
return 32 + (((code - 32) + shift) % (248 - 32 + 1));
};
var shiftString = function(s, shift) {
var s2 = "";
for(var i in s) {
var char_code = s.charCodeAt(i);
var new_char_code = shiftCharCode(char_code, shift);
s2 += String.fromCharCode(new_char_code);
}
return s2;
};
var shiftRight = function(s) {
return shiftString(s, 1);
};
var shiftLeft = function(s) {
return shiftString(s, -1);
};
var moveRight = function(s) {
var lastIndex = s.length - 1;
return s[lastIndex] + s.substring(0,lastIndex);
};
var moveLeft = function(s) {
return s.substring(1) + s[0];
};
var addNoice = function(s) {
var randomChar = Math.floor(Math.random()*(122-65+1)) + 65;
return s + String.fromCharCode(randomChar);
};
var removeNoice = function(s) {
return s.substring(0, s.length-1);
};
var encrypters = [shiftRight, moveRight, addNoice];
var decrypters = [shiftLeft, moveLeft, removeNoice];
return {
shiftLeft : shiftLeft,
encrypt: function(text, strength) {
var result = { encrypted:text, key:'' };
while (strength-- > 0) {
var nextKeyPart = Math.floor(Math.random()*encrypters.length);
var nextEncrypter = encrypters[nextKeyPart];
result.encrypted = nextEncrypter(result.encrypted);
result.key += nextKeyPart;
}
return result;
},
decrypt: function(text, key) {
for(var i=key.length-1; i >= 0 ; i--) {
text = decrypters[key[i]](text);
}
return text;
}
};
}();
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