Password Generator



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BrettBits > Java and Javascript Programs > Password Generator

To use this Javascript for your own, copy the contents of the textbox below, and paste them into Notepad. Then, save the contents as a .htm or .html file. The Javascript is now yours! Just ensure you give me proper credit for creating it.

Javascript Source Code

//refer to http://www.codehouse.com/javascript/tips/random_letter/
function createRandomLowerCaseLetter()
{
	return String.fromCharCode(97 + Math.round(Math.random() * 25)); //returns random lowercase letter
}
function createRandomUpperCaseLetter()
{
	if(isCaseSensitive()) //if password is to be case sensitive
		return String.fromCharCode(65 + Math.round(Math.random() * 25)); //return random uppercase letter
	else //if password is case insensitive
		return createRandomLowerCaseLetter(); //otherwise, return a random lowercase letter, because case does not matter
}
function createRandomNumber() //returns a random number between 0 and 9 inclusive
{
	return Math.round(Math.random()*9);
}

function getLetterOrNumber() //randomly chooses either a lowercase letter, uppercase letter, or number, and returns it
{
	randomNum = Math.random()*62;
	if(randomNum < 26)
		return createRandomUpperCaseLetter();
	else if(randomNum < 52)
		return createRandomLowerCaseLetter();
	else
		return createRandomNumber();
}

//prints the odds of guessing a generated password based on how many characters it contains,
//as well as whether or not it is case sensitive
function passwordProbability(pwLength) 
{
	possibleChars = 62;
	if(!isCaseSensitive())
		possibleChars -= 26;
	odds = Math.pow(possibleChars, pwLength);
	oddsMessage = "1 in "+odds
	document.pwform.oddsOfGuessing.size = oddsMessage.length;
	document.pwform.oddsOfGuessing.value = oddsMessage;
}

//generates a password of specified length, with both uppercase and lowercase letters (or just lowercase, 
//if case insensitive) as well as numbers. This will ensure it contains numbers if the user
//makes it a requirement.
function createPassword()
{
	pwLength = eval(document.pwform.pwlength.value);
	pwString = "";
	for(i = 0; i < pwLength; i++)
	{
		pwString += getLetterOrNumber();
	}

//if the password must contain numbers, and doesn't,
	//generate a new one
	if(mustContainNumbers() && !containsNumbers(pwString))
	{
		createPassword();
		return;
	}
	
	document.pwform.newpassword.size = Math.ceil(pwLength*1.2);
	document.pwform.newpassword.value = pwString;
	passwordProbability(pwLength);
	
}

//returns whether or not a given password contains at least one number
function containsNumbers(pw)
{
	hasNumbers = false;
	for(i = 0; i < pw.length; i++)
	{
		charCode = pw.charCodeAt(i);
		//if current digit is a number
		if(charCode >= 48 && charCode <= 57)
		{
			hasNumbers = true;
		}
	}
	return hasNumbers;
}

//returns whether or not the user has requested the password be case sensitive
function isCaseSensitive()
{
	return document.pwform.casesensitive.checked;
}
//returns whether or not the user has requested the password contain numbers
function mustContainNumbers()
{
	return document.pwform.mustContainNumbers.checked;
}

-->
</script>

Password length:
<input type = "text" name="pwlength" value="8" size="5" />
Case Sensitive:
<input type = "checkbox" name="casesensitive" checked="checked" />
Must Contain Numbers:
<input type = "checkbox" name="mustContainNumbers" />

<br />

Generated password:
<input type="text" name="newpassword" value="" readonly="readonly" />

<br />

Odds of Guessing Password:
<input type="text" name="oddsOfGuessing" value="" readonly="readonly" />

</center>
</form>

Alternatively, you can download the source .html file itself by right-clicking on the Download button below, and click "Save Target As..." or "Save Link As...":

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