Generating Random Passwords In ColdFusion Based On Sets Of Valid Characters

code-1.cfm

<!---
	We have to start out be defining what the sets of valid
	character data are. While this might not look elegant,
	notice that it gives a LOT of power over what the sets
	are without writing a whole lot of code or "condition"
	statements.
--->

<!--- Set up available lower case values. --->
<cfset strLowerCaseAlpha = "abcdefghijklmnopqrstuvwxyz" />

<!---
	Set up available upper case values. In this instance, we
	want the upper case to correspond to the lower case, so
	we are leveraging that character set.
--->
<cfset strUpperCaseAlpha = UCase( strLowerCaseAlpha ) />

<!--- Set up available numbers. --->
<cfset strNumbers = "0123456789" />

<!--- Set up additional valid password chars. --->
<cfset strOtherChars = "~!@##$%^&*" />

<!---
	When selecting random value, we want to be able to easily
	choose from the entire set. To this effect, we are going
	to concatenate all the previous valid character sets.
--->
<cfset strAllValidChars = (
	strLowerCaseAlpha &
	strUpperCaseAlpha &
	strNumbers &
	strOtherChars
	) />


<!---
	Create an array to contain the password ( think of a
	string as an array of character).
--->
<cfset arrPassword = ArrayNew( 1 ) />


<!---
	When creating a password, there are certain rules that we
	need to follow (as deemed by the business logic). That is,
	the password must:

	- must be exactly 8 characters in length
	- must have at least 1 number
	- must have at least 1 uppercase letter
	- must have at least 1 lower case letter
--->


<!--- Select the random number from our number set. --->
<cfset arrPassword[ 1 ] = Mid(
	strNumbers,
	RandRange( 1, Len( strNumbers ) ),
	1
	) />

<!--- Select the random letter from our lower case set. --->
<cfset arrPassword[ 2 ] = Mid(
	strLowerCaseAlpha,
	RandRange( 1, Len( strLowerCaseAlpha ) ),
	1
	) />

<!--- Select the random letter from our upper case set. --->
<cfset arrPassword[ 3 ] = Mid(
	strUpperCaseAlpha,
	RandRange( 1, Len( strUpperCaseAlpha ) ),
	1
	) />


<!---
	ASSERT: At this time, we have satisfied the character
	requirements of the password, but NOT the length
	requirement. In order to do that, we must add more
	random characters to make up a proper length.
--->


<!--- Create rest of the password. --->
<cfloop
	index="intChar"
	from="#(ArrayLen( arrPassword ) + 1)#"
	to="8"
	step="1">

	<!---
		Pick random value. For this character, we can choose
		from the entire set of valid characters.
	--->
	<cfset arrPassword[ intChar ] = Mid(
		strAllValidChars,
		RandRange( 1, Len( strAllValidChars ) ),
		1
		) />

</cfloop>


<!---
	Now, we have an array that has the proper number of
	characters and fits the business rules. But, we don't
	always want the first three characters to be of the
	same order (by type). Therefore, let's use the Java
	Collections utility class to shuffle this array into
	a "random" order.

	If you are not comfortable using the Java class, you
	can create your own shuffle algorithm.
--->
<cfset CreateObject( "java", "java.util.Collections" ).Shuffle(
	arrPassword
	) />


<!---
	We now have a randomly shuffled array. Now, we just need
	to join all the characters into a single string. We can
	do this by converting the array to a list and then just
	providing no delimiters (empty string delimiter).
--->
<cfset strPassword = ArrayToList(
	arrPassword,
	""
	) />