[RESOLVED] Password Generator Validation (Visual Studio 2010)

[ITdaz]

Hi Guys,

Need a little help with an application I'm creating. Its just a simple password generator. I have the application generating the password with no issues but I need to add a step in that checks for: 1 uppercase letter, 1 lowercase letter, 1 number and 1 special character before displaying the password. If the password doesn't contain these values the password should then generate again.

I would like to keep the code I have, i just want to add a step in at the end.

Thanks a lot in advance.

ps. I'm sorry if this is in the wrong place, this is my first post.

Here is my code:

Public Class Form1

    Dim AllCharacters As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789?!£$%^&*()_+[];'#,./?><~@:}{\|"
    Dim r As New Random
    Dim charIndex As Integer
    Dim finalpassword As String
    Dim passwordChars1() As Char = New Char(9) {}

 

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click



        For i As Integer = 0 To 9 - 1
            charIndex = r.Next(AllCharacters.Length)
            passwordChars1(i) = AllCharacters(charIndex)

       
        Next
        finalpassword = passwordChars1

        passwordbox.Text = finalpassword


     

    End Sub

[DataMiser]

One method would be to create 4 boolean variables. Then in your loop check the index to see which group of characters it falls into.
i.e if it falls within the first 26 then cUpperCase=True if the next 26 then cLowerCase=True, the next 10 for digits and the rest for special.

Set one of the booleans to true based on that result. When they loop is done then all four should be true if you have the characters you want.


BTW You have posted in the VB6 section but you are using a much later version and should be moved to the VB.Net section as all VB versions after 1998 are VB.Net

[ITdaz]

Thanks a lot for this, would you happen to know what the code for this would be ?


My apologies, I'll make sure this goes in the right place next time.

[dbasnett]

Another approach is to ensure that you have one of each. Because this might be homework there are no comments... Step through in the debugger and you will see what is going on.

    Private Shared prng As New Random
    Private ReadOnly Upper As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    Private ReadOnly Lower As String = "abcdefghijklmnopqrstuvwxyz"
    Private ReadOnly Numeric As String = "0123456789"
    Private ReadOnly Special As String = "?!£$%^&*()_+[];'#,./?><~@:}{\|"
    Const PasswordLength As Integer = 9
    Private Password As String

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim passWD As New System.Text.StringBuilder

        passWD.Append(Upper(prng.Next(Upper.Length)))
        passWD.Append(Lower(prng.Next(Lower.Length)))
        passWD.Append(Numeric(prng.Next(Numeric.Length)))
        passWD.Append(Special(prng.Next(Special.Length)))

        Do While passWD.Length <= PasswordLength
            Select Case prng.Next(1, 5)
                Case 1
                    passWD.Append(Upper(prng.Next(Upper.Length)))
                Case 2
                    passWD.Append(Lower(prng.Next(Lower.Length)))
                Case 3
                    passWD.Append(Numeric(prng.Next(Numeric.Length)))
                Case 4
                    passWD.Append(Special(prng.Next(Special.Length)))
            End Select
        Loop

        'the password
        Password = (From c In passWD.ToString Select c Order By prng.Next).ToArray

[Sitten Spynne]

Well, if it's always one of each, here's what I would do.

Start by generating a string with 1 random uppercase letter. Add 1 random lowercase letter. Add 1 random number. Add 1 random special character. Now fill in the rest of the length with random characters. When you're done, shuffle the order of this string. Voila. Let's get super fancy and write it functionally.

Imports System

Module Program

    Private _rng As New Random()

    Private _uppercase As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    Private _lowercase As String = "abcdefghijklmnopqrstuvwxyz"
    Private _numbers As String = "0123456789"
    Private _special As String = "!@#$%^&*()."

    Sub Main(args As String())
        Dim desiredLength = 12

        For i As Integer = 0 To 10
            Dim charStream = RequiredChars().Concat(RandomAnything().Take(desiredLength - 4))
            Dim password = Shuffle(charStream)
            Console.WriteLine("   {0}", password)
        Next
    End Sub

    Private Function Shuffle(ByVal input As IEnumerable(Of Char)) As String
        Dim buffer() As Char = input.ToArray()
        For i As Integer = buffer.Length - 1 To 1 Step -1
            Dim swapIndex = _rng.Next(i + 1)
            Dim temp = buffer(swapIndex)
            buffer(swapIndex) = buffer(i)
            buffer(i) = temp
        Next

        Return New String(buffer)
    End Function

    Private Iterator Function RequiredChars() As IEnumerable(Of Char)
        Yield RandomLowercases().First()
        Yield RandomUppercases().First()
        Yield RandomNumbers().First()
        Yield RandomSpecials().First()
    End Function

    Private Function RandomLowercases() As IEnumerable(Of Char)
        Return RandomItems(_lowercase)
    End Function

    Private Function RandomUppercases() As IEnumerable(Of Char)
        Return RandomItems(_uppercase)
    End Function

    Private Function RandomNumbers() As IEnumerable(Of Char)
        Return RandomItems(_numbers)
    End Function

    Private Function RandomSpecials() As IEnumerable(Of Char)
        Return RandomItems(_special)
    End Function

    Private Iterator Function RandomAnything() As IEnumerable(Of Char)
        Dim collections() = {_uppercase, _lowercase, _numbers, _special}
        While True
            Dim thisCollection = collections(_rng.Next(collections.Length))
            Yield thisCollection(_rng.Next(thisCollection.Length))
        End While
    End Function

    Private Iterator Function RandomItems(ByVal input As String) As IEnumerable(Of Char)
        While True
            Yield input(_rng.Next(input.Length))
        End While
    End Function

End Module

This is more or less what dbasnett just did, but I find the "use LINQ to shuffle" approach to be a smell.

[Shaggy Hiker]

I guess I'd ask whether or not this IS homework. We don't have an issue with helping with homework, but it would certainly restrict what solutions you'd be allowed to use.

[dday9]

To prevent you from generating multiple passwords that do not meet your criteria, what I would do is:

1. Get n amount of uppercase letters
2. Get n amount of lowercase letters
3. Get n amount of digits
4. Get n amount of special characters
5. Combine all of collections from steps 1-4
6. Order the combination randomly

Here is an example:

Private r As New Random
Private Function RandomPassword(ByVal lowercase_count As Integer, ByVal uppercase_count As Integer, ByVal number_count As Integer, ByVal special_count As Integer) As String
    Dim lowercase() As Char = "abcdefghijklmnopqrstuvwxyz".ToCharArray()
    Dim uppercase() As Char = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray()
    Dim numbers() As Char = "0123456789".ToCharArray()
    Dim special() As Char = "~`!@#$%^&*()_-+={[}]|\:;'<,>.?/".ToCharArray()

    Dim combination As New List(Of Char)
    combination.AddRange(Enumerable.Range(1, lowercase_count).Select(Function(c) lowercase(r.Next(0, lowercase_count - 1))))
    combination.AddRange(Enumerable.Range(1, uppercase_count).Select(Function(c) uppercase(r.Next(0, uppercase_count - 1))))
    combination.AddRange(Enumerable.Range(1, number_count).Select(Function(c) Convert.ToChar(numbers(r.Next(0, number_count - 1)))))
    combination.AddRange(Enumerable.Range(1, special_count).Select(Function(c) special(r.Next(0, special_count - 1))))

    Return New String(combination.OrderBy(Function(c) r.Next()).ToArray())
End Function

Fiddle: Live Demo

[Jenner]

I think I wrote something a while back similar to @dday9's solution. The only difference was I used ASCII character ranges and offsets rather than pre-typed strings getting loaded into character arrays.
But the math I used was I went through my four categories and randomly picked the minimum needed characters for each (typically 1), and however many other characters I needed for the password, I'd randomly pick one of the categories and randomly pick a character from it - then at the end, random shuffle everything.

[ITdaz]

I guess I'd ask whether or not this IS homework. We don't have an issue with helping with homework, but it would certainly restrict what solutions you'd be allowed to use.

I'm afraid this isn't homework, I'm just a complete beginner haha! Its actually for a helpdesk at work, we were audited and i have to sort this out for the guys before next week.

[jdc2000]

Actually, if you are really looking for security, random character passwords that no one can remember are actually less secure than reasonable length pass phrases that cannot be guessed or easily brute forced but that users can remember. Passwords that you can't remember tend to get written down on post-it notes, so unless you are also using something like KeePass, this might be an issue.

[ident]

Public Class Form1
    Private Function Match(value As String) As Boolean
        Return System.Text.RegularExpressions.Regex.IsMatch(value, "^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*(_|[^\w])).+$")
    End Function
End Class

[dbasnett]

I'm afraid this isn't homework, I'm just a complete beginner haha! Its actually for a helpdesk at work, we were audited and i have to sort this out for the guys before next week.

Here is a password generator class, take some time to understand what is going on with it. It gives you some options, see the constructor.

    Public Class PasswordGenerator
        Private Shared prng As New Random
        Private Shared ReadOnly Upper As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        Private Shared ReadOnly Lower As String = "abcdefghijklmnopqrstuvwxyz"
        Private Shared ReadOnly Numeric As String = "0123456789"
        Private Shared ReadOnly Special As String = "?!£$%^&*()_+[];'#,./?><~@:}{\|"
        Private Shared AllChs As New System.Text.StringBuilder
        Private Shared ReadOnly AllChsLen As Integer = Upper.Length + Lower.Length + Numeric.Length + Special.Length
        Private _PasswordLength As Integer
        Public Password As String
        Private _MustHave As PasswordMustHave
        Private _dupCharsAllowed As Boolean = True

        <FlagsAttribute> _
        Public Enum PasswordMustHave
            none = 0
            upper = 1 << 0
            lower = 1 << 1
            number = 1 << 2
            special = 1 << 3
            all = PasswordMustHave.upper Or PasswordMustHave.lower Or PasswordMustHave.number Or PasswordMustHave.special
        End Enum

        Public Sub New(Optional Length As Integer = 8, Optional MustHave As PasswordMustHave = PasswordMustHave.all, Optional DupCharsAllowed As Boolean = True)
            If Length > 0 AndAlso Length < AllChsLen Then
                Me._PasswordLength = Length
            Else
                Me._PasswordLength = 8
            End If
            Me._MustHave = MustHave
            Me._dupCharsAllowed = DupCharsAllowed
            Me.Generate() 'generate a password on creation
        End Sub

        Public Function Generate() As String

            Dim passWD As New System.Text.StringBuilder
            Dim ie As IEnumerable(Of Char)
            Dim idx As Integer
            'contruct all if needed
            If AllChs.Length <> AllChsLen Then
                AllChs.Length = 0
                AllChs.Append(Upper)
                AllChs.Append(Lower)
                AllChs.Append(Numeric)
                AllChs.Append(Special)
            End If

            passWD.Append(Me.MustHaveThese) 'add must have chars

            If Not Me._dupCharsAllowed Then 'allow dups
                'strip nulls added by Me.MustHaveThese
                For idx = AllChs.Length - 1 To 0 Step -1
                    If AllChs(idx) = ControlChars.NullChar Then
                        AllChs.Remove(idx, 1)
                    End If
                Next
            End If

            Do While passWD.Length < Me._PasswordLength 'add random chars
                idx = prng.Next(AllChs.Length)
                passWD.Append(AllChs(idx))
                If Not Me._dupCharsAllowed Then
                    'no dups
                    AllChs.Remove(idx, 1)
                End If
            Loop

            ie = From c In passWD.ToString Select c

            ' idx = ie.Count

            'shuffle and create password
            Me.Password = (From ch In ie Select ch Order By prng.Next Take Me._PasswordLength).ToArray
            Return Me.Password
        End Function

        Private Function MustHaveThese() As String
            Dim rv As New System.Text.StringBuilder
            If (Me._MustHave And PasswordMustHave.upper) = PasswordMustHave.upper Then
                rv.Append(Me.AddFrom(Upper))
            End If

            If (Me._MustHave And PasswordMustHave.lower) = PasswordMustHave.lower Then
                rv.Append(Me.AddFrom(Lower))
            End If

            If (Me._MustHave And PasswordMustHave.number) = PasswordMustHave.number Then
                rv.Append(Me.AddFrom(Numeric))
            End If

            If (Me._MustHave And PasswordMustHave.special) = PasswordMustHave.special Then
                rv.Append(Me.AddFrom(Special))
            End If

            Return rv.ToString
        End Function

        Private Function AddFrom(item As String) As Char
            Dim rv As Char = item(prng.Next(item.Length))
            If Not Me._dupCharsAllowed Then
                AllChs.Replace(rv, ControlChars.NullChar)
            End If
            Return rv
        End Function
    End Class

Here it is being used to construct 10 passwords

        Dim passwdGen As New PasswordGenerator()
        Dim lisPasswd As New List(Of String)

        For x As Integer = 1 To 10
            lisPasswd.Add(passwdGen.Password)
            passwdGen.Generate()
        Next

[ITdaz]

Thanks a lot for all the replies, I eventually went with the Private Shuffle function. I really appreciate all the help.

[ITdaz]

Here is a password generator class, take some time to understand what is going on with it. It gives you some options, see the constructor.

    Public Class PasswordGenerator
        Private Shared prng As New Random
        Private Shared ReadOnly Upper As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        Private Shared ReadOnly Lower As String = "abcdefghijklmnopqrstuvwxyz"
        Private Shared ReadOnly Numeric As String = "0123456789"
        Private Shared ReadOnly Special As String = "?!£$%^&*()_+[];'#,./?><~@:}{\|"
        Private Shared AllChs As New System.Text.StringBuilder
        Private Shared ReadOnly AllChsLen As Integer = Upper.Length + Lower.Length + Numeric.Length + Special.Length
        Private _PasswordLength As Integer
        Public Password As String
        Private _MustHave As PasswordMustHave
        Private _dupCharsAllowed As Boolean = True

        <FlagsAttribute> _
        Public Enum PasswordMustHave
            none = 0
            upper = 1 << 0
            lower = 1 << 1
            number = 1 << 2
            special = 1 << 3
            all = PasswordMustHave.upper Or PasswordMustHave.lower Or PasswordMustHave.number Or PasswordMustHave.special
        End Enum

        Public Sub New(Optional Length As Integer = 8, Optional MustHave As PasswordMustHave = PasswordMustHave.all, Optional DupCharsAllowed As Boolean = True)
            If Length > 0 AndAlso Length < AllChsLen Then
                Me._PasswordLength = Length
            Else
                Me._PasswordLength = 8
            End If
            Me._MustHave = MustHave
            Me._dupCharsAllowed = DupCharsAllowed
            Me.Generate() 'generate a password on creation
        End Sub

        Public Function Generate() As String

            Dim passWD As New System.Text.StringBuilder
            Dim ie As IEnumerable(Of Char)
            Dim idx As Integer
            'contruct all if needed
            If AllChs.Length <> AllChsLen Then
                AllChs.Length = 0
                AllChs.Append(Upper)
                AllChs.Append(Lower)
                AllChs.Append(Numeric)
                AllChs.Append(Special)
            End If

            passWD.Append(Me.MustHaveThese) 'add must have chars

            If Not Me._dupCharsAllowed Then 'allow dups
                'strip nulls added by Me.MustHaveThese
                For idx = AllChs.Length - 1 To 0 Step -1
                    If AllChs(idx) = ControlChars.NullChar Then
                        AllChs.Remove(idx, 1)
                    End If
                Next
            End If

            Do While passWD.Length < Me._PasswordLength 'add random chars
                idx = prng.Next(AllChs.Length)
                passWD.Append(AllChs(idx))
                If Not Me._dupCharsAllowed Then
                    'no dups
                    AllChs.Remove(idx, 1)
                End If
            Loop

            ie = From c In passWD.ToString Select c

            ' idx = ie.Count

            'shuffle and create password
            Me.Password = (From ch In ie Select ch Order By prng.Next Take Me._PasswordLength).ToArray
            Return Me.Password
        End Function

        Private Function MustHaveThese() As String
            Dim rv As New System.Text.StringBuilder
            If (Me._MustHave And PasswordMustHave.upper) = PasswordMustHave.upper Then
                rv.Append(Me.AddFrom(Upper))
            End If

            If (Me._MustHave And PasswordMustHave.lower) = PasswordMustHave.lower Then
                rv.Append(Me.AddFrom(Lower))
            End If

            If (Me._MustHave And PasswordMustHave.number) = PasswordMustHave.number Then
                rv.Append(Me.AddFrom(Numeric))
            End If

            If (Me._MustHave And PasswordMustHave.special) = PasswordMustHave.special Then
                rv.Append(Me.AddFrom(Special))
            End If

            Return rv.ToString
        End Function

        Private Function AddFrom(item As String) As Char
            Dim rv As Char = item(prng.Next(item.Length))
            If Not Me._dupCharsAllowed Then
                AllChs.Replace(rv, ControlChars.NullChar)
            End If
            Return rv
        End Function
    End Class

Here it is being used to construct 10 passwords

        Dim passwdGen As New PasswordGenerator()
        Dim lisPasswd As New List(Of String)

        For x As Integer = 1 To 10
            lisPasswd.Add(passwdGen.Password)
            passwdGen.Generate()
        Next

This Is brilliant!

[ident]

Public Class form1
    Private Sub GeneratePassword(allowed)
        Dim password = String.Empty
        Dim valid = Function(n)
                        Return System.Text.RegularExpressions.Regex.IsMatch(n, "^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*(_|[^\w])).+$")
                    End Function
 
        Do
            password = New String((allowed.OrderBy(Function(c) Guid.NewGuid).Take(10)).ToArray())
        Loop While Not valid(password)
 
 
        MessageBox.Show(password)
    End Sub
End Class

[ident]

Actually, if you are really looking for security, random character passwords that no one can remember are actually less secure than reasonable length pass phrases that cannot be guessed or easily brute forced but that users can remember. Passwords that you can't remember tend to get written down on post-it notes, so unless you are also using something like KeePass, this might be an issue.

so a 10 digit password i dont know is less secure than a 10 digit One i do?

[jdc2000]

so a 10 digit password i dont know is less secure than a 10 digit One i do?

Not sure what you are meaning by this. However, a password you don't know is always more secure, since if you don't know it chances are no one else does either.

My point is that a 128 character password that you have to write down is less secure than a 16 character password that you can remember. No one can read your mind (yet), but there is the potential that they might see or steal your password from a post-it note. Even electronic password "vaults" have potential issues if they get hacked, and some have been.

[ident]

Not sure what you are meaning by this. However, a password you don't know is always more secure, since if you don't know it chances are no one else does either.

My point is that a 128 character password that you have to write down is less secure than a 16 character password that you can remember. No one can read your mind (yet), but there is the potential that they might see or steal your password from a post-it note. Even electronic password "vaults" have potential issues if they get hacked, and some have been.

I was actually thinking you was suggesting a random password is less secure. How ever. .....

You can't suggest a known password is less secure because it's written down is secure over a random One because that's adding an unfair condition.

My last pass master password is 52 chars long. I know it off by heart. There is no pattern it's random. It's never been written down so how is that less secure than One i don't know? It is not. But this is not for this thread as off topic.

[Sitten Spynne]

The last few posts, expressed in comic form:

[ident]

and your point is