diff --git a/Ciphers/keyFinder.js b/Ciphers/keyFinder.js
index b223096c3..8e16dedb5 100644
--- a/Ciphers/keyFinder.js
+++ b/Ciphers/keyFinder.js
@@ -24,3 +24,118 @@ function keyFinder(str){ // str is used to get the input of encrypted string
 	}
 	return 0; // return 0 if found nothing
 }
+
+/* this sub-function is used to assist the keyfinder to find the key */
+function caesarCipherEncodeAndDecodeEngine(inStr, numShifted)
+{
+	let shiftNum = numShifted; 
+	let charCode = 0;
+	let outStr = "";
+	let shftedcharCode = 0;
+	let result = 0;
+
+	for (let i=0; i<inStr.length; i++){
+
+		charCode = inStr[i].charCodeAt();
+		shftedcharCode = charCode + shiftNum;
+		result = charCode;
+
+		if ( (charCode>=48 && charCode<=57))
+		{
+			if ( shftedcharCode < 48 ){
+
+		  		let diff = Math.abs(48-1-shftedcharCode)%10;
+
+				while( diff >= 10){
+		  			diff = diff%10;
+				}
+				document.getElementById("diffID").innerHTML = diff;
+
+				shftedcharCode = 57-diff;
+				
+				result = shftedcharCode;
+			}
+
+		  	else if ( shftedcharCode>=48 && shftedcharCode<=57 ){
+				result = shftedcharCode;
+			}
+
+			else if ( shftedcharCode > 57 ){
+
+		  		let diff = Math.abs(57+1-shftedcharCode)%10;
+
+				while( diff >= 10){
+		  			diff = diff%10;
+				}
+				document.getElementById("diffID").innerHTML = diff;
+
+				shftedcharCode = 48+diff;
+
+				result = shftedcharCode;
+			}
+
+
+		}
+
+		else if ( (charCode>=65 && charCode<=90) )
+		{
+
+		  	if (shftedcharCode <=64 ){
+
+		  		let diff = Math.abs(65-1-shftedcharCode)%26;
+
+				while( (diff%26) >= 26){
+		  			diff = diff%26;
+				}
+				shftedcharCode = 90-diff;
+				result = shftedcharCode;
+			}
+
+		  	else if ( shftedcharCode>=65 && shftedcharCode<=90 ){
+				result = shftedcharCode;
+			}
+
+			else if (shftedcharCode>90 ){
+				let diff = Math.abs(shftedcharCode-1-90)%26;
+
+				while( (diff%26) >= 26){
+		  			diff = diff%26;
+				}
+				shftedcharCode = 65+diff;
+				result = shftedcharCode;
+			}
+		
+		}
+
+		else if ( (charCode>=97 && charCode<=122))
+		{
+		  	if ( shftedcharCode<=96 ){
+
+		  		let diff = Math.abs(97-1-shftedcharCode)%26;
+
+				while( (diff%26) >= 26){
+		  			diff = diff%26;
+				}
+				shftedcharCode = 122-diff;
+				result = shftedcharCode;
+			}
+
+		  	else if ( shftedcharCode>=97 && shftedcharCode<=122 ){
+				result = shftedcharCode;
+			}
+
+			else if (shftedcharCode>122 ){
+				let diff = Math.abs(shftedcharCode-1-122)%26;
+
+				while( (diff%26) >= 26){
+		  			diff = diff%26;
+				}
+				shftedcharCode = 97+diff;
+				result = shftedcharCode;
+			}
+		
+		}
+		outStr = outStr + String.fromCharCode(parseInt(result));
+	}
+	return outStr;
+}