key Finder Algorithm
Key finders, also known as keyfinders, key locators, or electronic finders, are small electronic devices used to locate misplaced or stolen objects, such as keys, luggage, pets, or tools, and to transmit alerts, e.g., that one's restaurant table is ready or a nurse is needed. Some key finders honk or flash lights on demand.
/******************************************************
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
const wordBank = [
'I ',
'You ',
'We ',
'They ',
'He ',
'She ',
'It ',
' the ',
'The ',
' of ',
' is ',
'Is ',
' am ',
'Am ',
' are ',
'Are ',
' have ',
'Have ',
' has ',
'Has ',
' may ',
'May ',
' be ',
'Be ']
// let wordbankelementCounter = 0;
// let key = 0; // return zero means the key can not be found
const inStr = str.toString() // convert the input to String
let outStr = '' // store the output value
let outStrElement = '' // temporary store the word inside the outStr, it is used for comparison
for (let k = 0; k < 26; k++) { // try the number of key shifted, the sum of character from a-z or A-Z is 26
outStr = caesarCipherEncodeAndDecodeEngine(inStr, k) // use the encryption engine to decrypt the input string
// loop through the whole input string
for (let s = 0; s < outStr.length; s++) {
for (let i = 0; i < wordBank.length; i++) {
// initialize the outStrElement which is a temp output string for comparison,
// use a loop to find the next digit of wordBank element and compare with outStr's digit
for (let w = 0; w < wordBank[i].length; w++) {
outStrElement += outStr[s + w]
}
// console.log( k + outStrElement + wordBank[i] );//debug
// this part need to be optimize with the calculation of the number of occurrence of word's probabilities
// linked list will be used in the next stage of development to calculate the number of occurace of the key
if (wordBank[i] === outStrElement) {
return k // return the key number if founded
}
outStrElement = '' // reset the temp word
} // end for ( let i=0; i < wordBank.length; i++)
}
}
return 0 // return 0 if found nothing
}
/* this sub-function is used to assist the keyFinder to find the key */
function caesarCipherEncodeAndDecodeEngine (inStr, numShifted) {
const shiftNum = numShifted
let charCode = 0
let outStr = ''
let shiftedCharCode = 0
let result = 0
for (let i = 0; i < inStr.length; i++) {
charCode = inStr[i].charCodeAt()
shiftedCharCode = charCode + shiftNum
result = charCode
if ((charCode >= 48 && charCode <= 57)) {
if (shiftedCharCode < 48) {
let diff = Math.abs(48 - 1 - shiftedCharCode) % 10
while (diff >= 10) {
diff = diff % 10
}
document.getElementById('diffID').innerHTML = diff
shiftedCharCode = 57 - diff
result = shiftedCharCode
} else if (shiftedCharCode >= 48 && shiftedCharCode <= 57) {
result = shiftedCharCode
} else if (shiftedCharCode > 57) {
let diff = Math.abs(57 + 1 - shiftedCharCode) % 10
while (diff >= 10) {
diff = diff % 10
}
document.getElementById('diffID').innerHTML = diff
shiftedCharCode = 48 + diff
result = shiftedCharCode
}
} else if ((charCode >= 65 && charCode <= 90)) {
if (shiftedCharCode <= 64) {
let diff = Math.abs(65 - 1 - shiftedCharCode) % 26
while ((diff % 26) >= 26) {
diff = diff % 26
}
shiftedCharCode = 90 - diff
result = shiftedCharCode
} else if (shiftedCharCode >= 65 && shiftedCharCode <= 90) {
result = shiftedCharCode
} else if (shiftedCharCode > 90) {
let diff = Math.abs(shiftedCharCode - 1 - 90) % 26
while ((diff % 26) >= 26) {
diff = diff % 26
}
shiftedCharCode = 65 + diff
result = shiftedCharCode
}
} else if ((charCode >= 97 && charCode <= 122)) {
if (shiftedCharCode <= 96) {
let diff = Math.abs(97 - 1 - shiftedCharCode) % 26
while ((diff % 26) >= 26) {
diff = diff % 26
}
shiftedCharCode = 122 - diff
result = shiftedCharCode
} else if (shiftedCharCode >= 97 && shiftedCharCode <= 122) {
result = shiftedCharCode
} else if (shiftedCharCode > 122) {
let diff = Math.abs(shiftedCharCode - 1 - 122) % 26
while ((diff % 26) >= 26) {
diff = diff % 26
}
shiftedCharCode = 97 + diff
result = shiftedCharCode
}
}
outStr = outStr + String.fromCharCode(parseInt(result))
}
return outStr
}
console.log('Testing: ' + keyFinder('test')) // returns 0
