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Merge pull request #78 from winsonrich/patch-4

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Create keyFinder.js
This commit is contained in:
Mohit Sharma
2018-10-30 15:11:05 +05:30
committed by GitHub
parent 7b82729d7e 7a04d2ad86
commit 9cabd462ec
1 changed files with 27 additions and 0 deletions
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/******************************************************
Find and retrieve the encryption key automatically
Note: This is a draft version, please help to modify, Thanks!
******************************************************/
function keyFinder(str){ // str is used to get the input of encrypted string
var key = 0; // return zero means the key can not be found
var wordbank =["is","Is","am","Am","are","Are","have","Have","has","Has","may","May","be","Be"];
//var shiftNum = 0; //count the number of key shifted
var inStr = str.toString(); //convert the input to String
var outStr = ""; // store the output value
var wordInOutStr = ""; // temporary store the word inside the outStr, it is used for comparison
//document.getElementById("debug").innerHTML = shiftNum; // debug: display the shifted number(s)
for (var i=0; i<(52); i++){ //try the number of key shifted, the sum of character from a-z and A-Z is 26*2=52
outStr = caesarCipherEncodeAndDecodeEngine(inStr,i); // use the encrytpion engine to decrypt the input string, shiftNum=i
for ( var i=0; i<wordbank.length; i++){
// use a loop to find the next digit of wordbank element and compare with outStr's digit
for ( var j=0; j < wordbank[i].length; j++){
wordInOutStr += outStr[i+j];
}
// this part need to be optimize with the calculation of the number of occurance of word's probabilities
if (wordbank[i] == wordInOutStr){
key=i;
}
}
}
return key;
}