Simple License Encryption Class

[bmahler]

Ok, I wrote this from a php encryption function that I had. It takes a PassKey and will encrypt it with a random value each time. It is a very simple encryption but for my uses it seemed fine. I thought I would share it. I will include both the vb php versions.

VB Version

Public Class License
 
#Region " VARIABLES "
    Private strcode As String() = {"", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"}
    Private _PassKey As String
#End Region
 
#Region " ENUM "
    Public Enum ValidationResult
        Trial
        Valid
        Invalid
    End Enum
#End Region
 
#Region " PROPERTIES "
    Public Property PassKey() As String
        Get
            Return _PassKey
        End Get
        Set(ByVal value As String)
            _PassKey = value.Replace(" ",String.Empty).ToUpper
        End Set
    End Property
#End Region
 
#Region " PUBLIC FUNCTIONS "
    Public Function GenerateRandomPassKey() As String
        Dim rand As New Random
        Dim passKey As String = String.Empty
        For i As Integer = 0 To 22
            Dim r As Integer = rand.Next(48, 90)
            Do Until r < 58 OrElse r > 64
                r = rand.Next(48, 90)
            Loop
            passKey &= Chr(r)
        Next
        Return passKey
    End Function
 
    Public Function GenerateKey() As String
        If _PassKey = String.Empty Then
            Return "Please Enter Passkey or generate a random passkey.  The longer the passkey, the greater the security."
        End If
        Dim nstr As String() = strsplt(_PassKey, 2)
        Dim output As String = String.Empty
        Dim tmp As String = String.Empty
        For i As Integer = 0 To nstr.GetUpperBound(0)
            tmp &= convert_keyto_value(nstr(i))
        Next
 
        For i As Integer = 0 To tmp.Length - 1
            output &= tmp.Substring(i, 1)
            If i > 0 AndAlso i <> tmp.Length - 1 AndAlso (i + 1) Mod 5 = 0 Then
                output &= "-"
            End If
        Next
        Return output
    End Function
 
    Public Function ValidateKey(ByVal thetext As String) As Boolean
        thetext = thetext.Replace("-"c, String.Empty)
        Dim nstr As String() = strsplt(thetext, 3)
        Dim output As String = String.Empty
        For i As Integer = 0 To nstr.GetUpperBound(0)
            output &= deRandomize(nstr(i))
        Next
        If output = _PassKey Then
            Return True
        Else
            Return False
        End If
    End Function
 
#End Region
 
#Region " PRIVATE FUNCTIONS "
    Private Function strsplt(ByVal thetext As String, Optional ByVal num As Integer = 1) As String()
        Dim arr As New List(Of String)
        Dim i As Integer
        Dim y As String
        For i = 0 To thetext.Length - 1 Step num
            If i + num > thetext.Length - 1 Then
                y = thetext.Substring(i, (thetext.Length - i))
            Else
                y = thetext.Substring(i, num)
            End If
 
            arr.Add(y)
        Next
        Return arr.ToArray
    End Function
 
    Private Function key_locator(ByVal code As String) As Integer
        For i As Integer = 0 To strcode.GetUpperBound(0)
            If strcode(i) = code Then
                Return i
            End If
        Next
        Return Nothing
    End Function
 
    Private Function add_random_key(ByVal thetext As String) As Integer()
        Dim newcode As New List(Of Integer)
        Dim rnd As New Random()
        Dim r As Integer = rnd.Next(1, strcode.Length - 2)
        Dim x As Integer
        Dim tmp As Integer
        For i As Integer = 0 To thetext.Length - 1
            x = key_locator(thetext.Substring(i, 1))
            tmp = x + r
            If tmp > strcode.Length - 1 Then
                tmp = tmp - (strcode.Length - 1)
            End If
            newcode.Add(tmp)
        Next
        newcode.Add(r)
        Return newcode.ToArray
    End Function
 
    Private Function convert_keyto_value(ByVal thetext As String) As String
        Dim a As Integer() = add_random_key(thetext)
        Dim strReturn As String = String.Empty
        Do Until Array.IndexOf(a, strcode.Length) = -1
            a = add_random_key(thetext)
        Loop
        For i As Integer = 0 To a.GetUpperBound(0)
            strReturn &= strcode(a(i))
        Next
        Return strReturn
    End Function
 
    Private Function deRandomize(ByVal thetext As String) As String
        Dim arr As String() = strsplt(thetext, thetext.Length - 1)
        Dim s, t, newcode As Integer
        Dim output As String = String.Empty
 
        For x As Integer = 0 To thetext.Length - 2
            s = key_locator(arr(0).Substring(x, 1))
            t = key_locator(arr(1))
            newcode = s - t
            If newcode < 0 Then
                newcode += (strcode.Length - 1)
            End If
            If newcode = 0 And s <> 0 Then
                newcode = (strcode.Length - 1)
            End If
            output &= strcode(newcode)
        Next
        Return output
    End Function
#End Region
 
End Class

Usage
You can either select your own passkey to use for this or you can generate a random passkey. The random Passkey generates a random 23 character string.

Creating Licenses

Dim Lic As New License
Dim pKey As String = lic.GenerateRandomPassKey 'You need to save this key because it is used to validate any licenses you create
lic.PassKey = pKey
Dim LicenseKey As String = lic.GenerateKey

Validating Licenses

Dim Lic As New License
Lic.PassKey = YOUR_PASSKEY
Dim isValid As Boolean = lic.ValidateKey("THEY KEY TO VALIDATE")

The PHP File

<?php
$strcode=array('','0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z');

function strsplt($thetext,$num=1){
    $arr=array();
    while ($i<strlen($thetext)){
        $y=substr($thetext,$i,$num);
        if (isset($y)){
            $arr[]=$y;
        }
        $i=$i+$num;
    }
    return $arr;
}

function key_locator($code,$strcode){
    while (list($key, $val) = each($strcode)) {
        if ($val==$code){
            $x=$key;
        }
    }
    return $x;
}

function add_random_key($thetext){
    global $strcode;
    $newcode=array();
    $rnd=rand(1,intval(count($strcode))-2);
    for ($i=0;$i<strlen($thetext);$i++){
        $x=key_locator(substr($thetext,$i,1),$strcode);
        $temp=$x+$rnd;
        if($temp>intval(count($strcode)-1)){
            $temp=$temp-intval(count($strcode)-1);
        }
        $newcode[]=$temp;
        $temp="";
    }
    $newcode[]=$rnd;
    return $newcode;
}

function convert_keyto_value($thetext){
    global $strcode;
    $a=add_random_key($thetext);
    while (in_array(count($strcode)-1,$a)==true){
        $a=add_random_key($thetext);
    }
    for ($i=0;$i<strlen($thetext)+1;$i++){
        $output.=$strcode[$a[$i]];
    }
    return $output;
}

function derandomized($thetext){
    global $strcode;;
    $arr=strsplt($thetext,intval(strlen($thetext)-1));
    for ($x=0;$x<strlen($thetext)-1;$x++){
        $s=key_locator(substr($arr[0],$x,1),$strcode);
        $t=key_locator($arr[1],$strcode);
        $newcode=$s-$t;
        if ($newcode<0){
            $newcode=$newcode+intval(count($strcode)-1);
        }
        if ($newcode==0&&$s<>0){
            $newcode=count($strcode)-1;
        }
        $output.=$strcode[$newcode];
    }
    return $output;
}

function encrypt($thetext){
    global $strcode;;
    $nstr=strsplt($thetext,2);
    for ($i=0;$i<count($nstr);$i++){
        $output.=convert_keyto_value($nstr[$i]);
    }
    return $output;
}

function decrypt($thetext){
    global $strcode;;
    $nstr=strsplt($thetext,3);
    for ($i=0;$i<count($nstr);$i++){
        $output.=derandomized($nstr[$i]);
    }
    return $output;
}
?>