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Generate a Random String Key in VB.NET

, 28 Jul 2005
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A slightly more intelligent random string generator.

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Introduction

I had to create a piece of code that will give me a set of randomly generated keys. Each key had to consist of letters and numbers, and the letters could be either (randomly) lowercase or uppercase.

Looking at some sample code on the web, I could not find what I needed. All the examples I found either generated numbers only, or letters only. I also wanted this random key to be based on a certain rule that made it "not straightforward" random, so, I came up with this little piece of code.

Using the code

The way it works is as follows:

You feed it with a string of letters: KeyLetters, a string of numbers: KeyNumbers, and how many characters you want the random key to be: Keychars. We then call Generate() which goes and generates a random number through the Randomize() statement and the Rnd() function.

Multiply Rnd() by 111 -could be any number we choose which is sufficient enough to bring the value above zero. If the resulting number is an even number, then our random character will be a letter. If we get an odd number, then our random character will be a number. To generate a random character, we generate a random index for one of the character arrays (depending on what our random character will be). Once we have an index which is >= o, we use it to get the value in the corresponding index in the character array.

If we are generating a number, then that is our random character. If we are generating a letter, then we need to determine whether we want it uppercase or lowercase. For that purpose we generate another random number by multiplying the value of Rnd() by 99 – could be any other number too – and then determine whether the result is even or odd. This time, we capitalize the letter if we get an odd number, otherwise we leave it as it is.

And so on, … the loop keeps "looping" while using, and we use a StringBuilder to construct our resulting string , until we've generated the desired number of characters for our Random Key. We convert the StringBuilder to String and return it with the function.

Note: XML comments in the source code were generated using "VBXC - VB.NET XML Commentor beta 3". I highly recommend it.

Module1.vb

Module Module1
    Sub Main()
        Dim KeyGen As RandomKeyGenerator
        Dim NumKeys As Integer
        Dim i_Keys As Integer
        Dim RandomKey As String

        ''' MODIFY THIS TO GET MORE KEYS    - LAITH - 27/07/2005 22:48:30 -
        NumKeys = 20

        KeyGen = New RandomKeyGenerator
        KeyGen.KeyLetters = "abcdefghijklmnopqrstuvwxyz"
        KeyGen.KeyNumbers = "0123456789"
        KeyGen.KeyChars = 12
        For i_Keys = 1 To NumKeys
            RandomKey = KeyGen.Generate()
            Console.WriteLine(RandomKey)
        Next
        Console.WriteLine("Press any key to exit...")
        Console.Read()
    End Sub
End Module

RandomKeyGenerator.vb

Option Strict On
Imports System.Text
''' <date>27072005</date><time>070339</time>
''' <type>class</type>
''' <summary>
''' REQUIRES PROPERTIES: KeyLetters, KeyNumbers, MaxChars
''' </summary>
Public Class RandomKeyGenerator
    Dim Key_Letters As String
    Dim Key_Numbers As String
    Dim Key_Chars As Integer
    Dim LettersArray As Char()
    Dim NumbersArray As Char()

    ''' <date>27072005</date><time>071924</time>
    ''' <type>property</type>
    ''' <summary>
    ''' WRITE ONLY PROPERTY. HAS TO BE SET BEFORE CALLING GENERATE()
    ''' </summary>
    Protected Friend WriteOnly Property KeyLetters() As String
        Set(ByVal Value As String)
            Key_Letters = Value
        End Set
    End Property

    ''' <date>27072005</date><time>071924</time>
    ''' <type>property</type>
    ''' <summary>
    ''' WRITE ONLY PROPERTY. HAS TO BE SET BEFORE CALLING GENERATE()
    ''' </summary>
    Protected Friend WriteOnly Property KeyNumbers() As String
        Set(ByVal Value As String)
            Key_Numbers = Value
        End Set
    End Property

    ''' <date>27072005</date><time>071924</time>
    ''' <type>property</type>
    ''' <summary>
    ''' WRITE ONLY PROPERTY. HAS TO BE SET BEFORE CALLING GENERATE()
    ''' </summary>
    Protected Friend WriteOnly Property KeyChars() As Integer
        Set(ByVal Value As Integer)
            Key_Chars = Value
        End Set
    End Property

    ''' <date>27072005</date><time>072344</time>
    ''' <type>function</type>
    ''' <summary>
    ''' GENERATES A RANDOM STRING OF LETTERS AND NUMBERS.
    ''' LETTERS CAN BE RANDOMLY CAPITAL OR SMALL.
    ''' </summary>
    ''' <returns type="String">RETURNS THE
    '''         RANDOMLY GENERATED KEY</returns>
    Function Generate() As String
        Dim i_key As Integer
        Dim Random1 As Single
        Dim arrIndex As Int16
        Dim sb As New StringBuilder
        Dim RandomLetter As String

        ''' CONVERT LettersArray & NumbersArray TO CHARACTR ARRAYS
        LettersArray = Key_Letters.ToCharArray
        NumbersArray = Key_Numbers.ToCharArray

        For i_key = 1 To Key_Chars
            ''' START THE CLOCK    - LAITH - 27/07/2005 18:01:18 -
            Randomize()
            Random1 = Rnd()
            arrIndex = -1
            ''' IF THE VALUE IS AN EVEN NUMBER WE GENERATE A LETTER,
            ''' OTHERWISE WE GENERATE A NUMBER  
            '''          - LAITH - 27/07/2005 18:02:55 -
            ''' THE NUMBER '111' WAS RANDOMLY CHOSEN. ANY NUMBER
            ''' WILL DO, WE JUST NEED TO BRING THE VALUE
            ''' ABOVE '0'     - LAITH - 27/07/2005 18:40:48 -
            If (CType(Random1 * 111, Integer)) Mod 2 = 0 Then
                ''' GENERATE A RANDOM INDEX IN THE LETTERS
                ''' CHARACTER ARRAY   - LAITH - 27/07/2005 18:47:44 -
                Do While arrIndex < 0
                    arrIndex = _
                     Convert.ToInt16(LettersArray.GetUpperBound(0) _
                     * Random1)
                Loop
                RandomLetter = LettersArray(arrIndex)
                ''' CREATE ANOTHER RANDOM NUMBER. IF IT IS ODD,
                ''' WE CAPITALIZE THE LETTER
                '''      - LAITH - 27/07/2005 18:55:59 -
                If (CType(arrIndex * Random1 * 99, Integer)) Mod 2 <> 0 Then
                    RandomLetter = LettersArray(arrIndex).ToString
                    RandomLetter = RandomLetter.ToUpper
                End If
                sb.Append(RandomLetter)
            Else
                ''' GENERATE A RANDOM INDEX IN THE NUMBERS
                ''' CHARACTER ARRAY   - LAITH - 27/07/2005 18:47:44 -
                Do While arrIndex < 0
                    arrIndex = _
                      Convert.ToInt16(NumbersArray.GetUpperBound(0) _
                      * Random1)
                Loop
                sb.Append(NumbersArray(arrIndex))
            End If
        Next
        Return sb.ToString
    End Function
End Class

License

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About the Author

Laith M. Zraikat
Web Developer
United States United States
No Biography provided

Comments and Discussions

 
Questioncode in vb.net(windows application) PinmemberMember 927728020-Jul-12 1:34 
QuestionThanx Pinmemberafridibest24-Apr-12 1:18 
Generalgood job Pinmemberbeyhano31-Mar-08 13:13 
GeneralGood but Pinmembersmiling4ever10-Aug-05 4:15 
GeneralRe: Good but PinmemberBaiju Nagori12-May-06 10:22 
QuestionRe: Good but Pinmembermhovidz13-Apr-07 8:51 
AnswerRe: Good but Pinmembersmiling4ever13-Apr-07 9:15 
AnswerRe: Good but PinmemberLaith M. Zraikat5-Aug-08 1:35 
GeneralRe: Good but PinmemberShane Story6-Feb-09 5:31 
GeneralRe: Good but PinmemberAnthony Granger10-Feb-09 15:27 
[code]' zRanP, written by NightCrawler03X
' Copyright (C) 2009 NightCrawler03X, All Rights Reserved
' In regards to this software, permission to use, copy, modify, reproduce, redistribute (under the definitions of international copyright law),
' is hereby granted, but the above copyright notice must remain, and the following disclaimer applies:
'' ''THIS SOFTWARE IS PROVIDED ''AS IS'', AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
'' ''THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
'' ''THE COPYRIGHT HOLDER OF THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
'' ''BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERUPTION)
'' ''HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
'' ''(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
'' ''OF SUCH DAMAGE.
 
'' Should you have any questions, direct them to nightcrawler03x@gmail.com
'' You may also find me under the following aliases at the following forums (just sign up and send me a private message):
'' zerohero (http://forums.xkcd.com),
'' NightCrawler03X (http://www.ubuntuforums.org, http://www.programmingforums.org, http://www.daniweb.com)
 
Option Strict On
Option Explicit On
Module Module1
 
Private amountPasswords As Integer = 0
Private maxLength As Integer = 0
Private minLength As Integer = 0
 
Private Function generatePassword(ByRef minLength As Integer, ByRef maxLength As Integer) As String
Dim s As String = "" : Dim passwordLength As Integer = 0 : generatePassword = ""
Do : Randomize() : passwordLength = Convert.ToInt32(minLength + Int(Rnd() * (maxLength - minLength)))
Loop Until passwordLength >= minLength
For i As Integer = 1 To passwordLength Step 1 : Randomize()
Do : s = Chr(Convert.ToInt32(33 + Int(Rnd() * 94)))
Loop Until Not s = Chr(34) : generatePassword += s : Next
End Function
 
Private Sub inputMaxLength()
Do : Try : System.Console.Write("Maximum length: ")
maxLength = Convert.ToInt32(Console.ReadLine())
If Not maxLength < minLength Then Return Else System.Console.WriteLine("Cannot be below minimum length")
Catch ex As Exception : System.Console.WriteLine("GIGO") : End Try : Loop
End Sub
 
Private Sub inputMinLength()
Do : Try : System.Console.Write("Minimum length: ")
minLength = Convert.ToInt32(Console.ReadLine())
If Not minLength < 1 Then Return Else System.Console.WriteLine("Must be 1 or greater")
Catch ex As Exception : System.Console.WriteLine("GIGO") : End Try : Loop
End Sub
 
Private Sub inputAmount()
Do : Try : System.Console.Write("Amount of passwords: ")
amountPasswords = Convert.ToInt32(Console.ReadLine())
If Not amountPasswords <= 0 Then Return Else System.Console.WriteLine("GIGO")
Catch ex As Exception : System.Console.WriteLine("GIGO") : End Try : Loop
End Sub
 
Private Sub finalResults()
System.Console.WriteLine("")
For i As Integer = 1 To amountPasswords Step 1
System.Console.WriteLine(generatePassword(minLength, maxLength))
System.Console.WriteLine() : Next
System.Console.WriteLine("Make sure to change your password regularly.")
System.Console.WriteLine("NEVER write it down. Write it in your head, and no-where-else.")
System.Console.WriteLine("Share your password with NO-ONE")
End Sub
 
Sub Main()
inputAmount() : inputMinLength() : inputMaxLength() : finalResults() _
: System.Console.Write("Press any key to quit... ") : System.Console.ReadKey()
End Sub
 
End Module
[/code]

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Article Copyright 2005 by Laith M. Zraikat
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