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a93d5cfe67
1. modified the identifiers and used the suitable identifiers for the variables 2. leave the loop when a key is match and found to increase the speed of searching in this stage of development 3. return the key number if founded, return 0 if found nothing
27 lines
1.5 KiB
JavaScript
27 lines
1.5 KiB
JavaScript
/******************************************************
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Find and retrieve the encryption key automatically
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Note: This is a draft version, please help to modify, Thanks!
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******************************************************/
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function keyFinder(str){ // str is used to get the input of encrypted string
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const wordbank =["is","Is","am","Am","are","Are","have","Have","has","Has","may","May","be","Be"];
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let key = 0; // return zero means the key can not be found
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let inStr = str.toString(); //convert the input to String
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let outStr = ""; // store the output value
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let wordInOutStr = ""; // temporary store the word inside the outStr, it is used for comparison
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for (let 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
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outStr = caesarCipherEncodeAndDecodeEngine(inStr,i); // use the encrytpion engine to decrypt the input string, shiftNum=i
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for ( let i=0; i<wordbank.length; i++){
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// use a loop to find the next digit of wordbank element and compare with outStr's digit
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for ( let j=0; j < wordbank[i].length; j++){
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wordInOutStr += outStr[i+j];
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}
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// this part need to be optimize with the calculation of the number of occurance of word's probabilities
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// linked list will be used in the next stage of development to calculate the number of occurace of the key
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if (wordbank[i] == wordInOutStr){
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return key=i; // return the key number if founded
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}
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}
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}
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return 0; // return 0 if found nothing
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}
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