Programming Forums > Application Development > Visual Basic .NET

emdiesse · Jan 6th, 2006, 4:26 PM

Hello.

I would like to MD5 a value of two text box's.
txtOne
txtTwo

So I would like to make the two textboxes into a variable.

(Toggle Plain Text)

Dim Text As String
String = txtOne + txtTwo

I believe that would be how

Then MD5 the variable.
I am not sure how I do this but I have found this, which to me, appears to be relative.

(Toggle Plain Text)

    Function getMd5Hash(ByVal input As String) As String
        ' Create a new instance of the MD5 object.
        Dim md5Hasher As MD5 = MD5.Create()

        ' Convert the input string to a byte array and compute the hash.
        Dim data As Byte() = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input))

        ' Create a new Stringbuilder to collect the bytes
        ' and create a string.
        Dim sBuilder As New StringBuilder()

        ' Loop through each byte of the hashed data 
        ' and format each one as a hexadecimal string.
        Dim i As Integer
        For i = 0 To data.Length - 1
            sBuilder.Append(data(i).ToString("x2"))
        Next i

        ' Return the hexadecimal string.
        Return sBuilder.ToString()

    End Function

Please can someone help me to make this work how I would like it to work

Polyphemus_ · Jan 6th, 2006, 5:41 PM

Please tell us what doesn't work, or what works wrong. We are quite good at programming, but we fail miserably at mind reading.

emdiesse · Jan 6th, 2006, 6:29 PM

Quote:

Originally Posted by Polyphemus_

Please tell us what doesn't work, or what works wrong. We are quite good at programming, but we fail miserably at mind reading.

Sorry. I thought I had but after reading it I have realised I missed out some vital Info.

The second bit of code is something I have found on the internet concerning strings and MD5. I am tring to convert this to something that will change a value of a variable (string variable) to MD5, but I am unsure as to how I would do this.

I got the code from here:
http://msdn2.microsoft.com/en-us/lib...aphy.md5.aspx#

Rory · Jan 7th, 2006, 1:48 PM

OK, just a few things about that code: Firstly the data should be passed as a reference type to prevent needless duplication of memory, which is important if you're hashing a relatively large amount of data.

Secondly, however, if you're using this to hash entire files, you should use System.Security.Cryptography.MD5.ComputeHash with a filestream instead, and wrapper this in a callback thread so that your application does not "freeze" while the hash is being calculated, perhaps even giving user feedback.

Then again if the reliability and speed are important, you might want to look for an open source optimised ASM library like OpenSSL instead, as the .NET FW's routines are written in CLR and are appallingly slow.

Anyway here's your function:

(Toggle Plain Text)

Public Function getMd5Hash(ByRef Data As String) As String
        Dim md5Hasher As System.Security.Cryptography.MD5 = System.Security.Cryptography.MD5.Create()

        Dim Hash As Byte() = md5Hasher.ComputeHash(System.Text.Encoding.ASCII.GetBytes(Data))

        Dim sBuilder As System.Text.StringBuilder = New System.Text.StringBuilder(32)

        For I As Integer = 0 To Hash.Length - 1
            sBuilder.Append(Hash(I).ToString("x2"))
        Next I

        Return sBuilder.ToString()

    End Function

emdiesse · Feb 9th, 2006, 11:45 AM

Quote:

Originally Posted by Rory

Anyway here's your function:

(Toggle Plain Text)

Public Function getMd5Hash(ByRef Data As String) As String
        Dim md5Hasher As System.Security.Cryptography.MD5 = System.Security.Cryptography.MD5.Create()

        Dim Hash As Byte() = md5Hasher.ComputeHash(System.Text.Encoding.ASCII.GetBytes(Data))

        Dim sBuilder As System.Text.StringBuilder = New System.Text.StringBuilder(32)

        For I As Integer = 0 To Hash.Length - 1
            sBuilder.Append(Hash(I).ToString("x2"))
        Next I

        Return sBuilder.ToString()

    End Function

Thanks for the hints and the code

I have made the amendments to my code and I have this as the code:

(Toggle Plain Text)

Imports System
Imports System.Security.Cryptography
Imports System.Text



Module Generate
    ' Hash an input string and return the hash as
    ' a 32 character hexadecimal string.
    Public Function getMd5Hash(ByRef Data As String) As String
        Dim md5Hasher As System.Security.Cryptography.MD5 = System.Security.Cryptography.MD5.Create()

        Dim Hash As Byte() = md5Hasher.ComputeHash(System.Text.Encoding.ASCII.GetBytes(Data))

        Dim sBuilder As System.Text.StringBuilder = New System.Text.StringBuilder(32)

        For I As Integer = 0 To Hash.Length - 1
            sBuilder.Append(Hash(I).ToString("x2"))
        Next I

        Return sBuilder.ToString()
    End Function



    Sub Main()
        Dim source As String
        Dim frmMd5 As New frmMd5
        source = frmMd5.txtOne.Text & frmMd5.txtApp.Text
        Dim hash As String = getMd5Hash(source)
        frmMd5.txtEncryptedText.Text = hash
    End Sub

End Module



Public Class frmMd5
    Inherits System.Windows.Forms.Form



    Private Sub btnGen_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGen.Click
            Main()  'Run Sub Main(), Generates md5

I get this error when I click generate:

(Toggle Plain Text)

An unhandled exception of type 'System.InvalidOperationException' occurred in system.windows.forms.dll

Additional information: It is invalid to start a second message loop on a single thread. Use Application.RunDialog or Form.ShowDialog instead.

It also highlights the text "frmMd5" in green. I have also highlighted this bit in green in the code.

Please help

emdiesse · Feb 11th, 2006, 3:48 PM

Ahah. Done it.

I would now like to know how to change the length of the the output of my Md5 hash. I would like it to be possible to make it longer or shorter by the use of another text box.

How do I do this?
Do the numbers have to be base 2 (2,4,8,16,32,64,etc), or can they be any integer?

I have changed the code to this:

(Toggle Plain Text)

Imports System
Imports System.Security.Cryptography
Imports System.Text
Module Generate
    Public Function getMd5Hash(ByRef Data As String) As String
        Dim md5Hasher As System.Security.Cryptography.MD5 = System.Security.Cryptography.MD5.Create()

        Dim Hash As Byte() = md5Hasher.ComputeHash(System.Text.Encoding.ASCII.GetBytes(Data))

        Dim sBuilder As System.Text.StringBuilder = New System.Text.StringBuilder(32)

        For I As Integer = 0 To Hash.Length - 1
            sBuilder.Append(Hash(I).ToString("x2"))
        Next I

        Return sBuilder.ToString()

    End Function
End Module



Public Class frmMd5
    Inherits System.Windows.Forms.Form

    Private Sub btnGen_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGen.Click
            Dim source As String
            source = txtOne.Text & txtTwo.Text
            Dim hash As String = getMd5Hash(source)
            txtEnc.Text = hash
    End Sub
End Class

Thanks.

Jan 6th, 2006, 4:26 PM	#1
emdiesse Programmer Join Date: Jul 2004 Location: Hampshire Posts: 56 Rep Power: 5	Md5 Hello. I would like to MD5 a value of two text box's. txtOne txtTwo So I would like to make the two textboxes into a variable. (Toggle Plain Text) Dim Text As String String = txtOne + txtTwo Dim Text As String String = txtOne + txtTwo I believe that would be how Then MD5 the variable. I am not sure how I do this but I have found this, which to me, appears to be relative. (Toggle Plain Text) Function getMd5Hash(ByVal input As String) As String ' Create a new instance of the MD5 object. Dim md5Hasher As MD5 = MD5.Create() ' Convert the input string to a byte array and compute the hash. Dim data As Byte() = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input)) ' Create a new Stringbuilder to collect the bytes ' and create a string. Dim sBuilder As New StringBuilder() ' Loop through each byte of the hashed data ' and format each one as a hexadecimal string. Dim i As Integer For i = 0 To data.Length - 1 sBuilder.Append(data(i).ToString("x2")) Next i ' Return the hexadecimal string. Return sBuilder.ToString() End Function Function getMd5Hash(ByVal input As String) As String ' Create a new instance of the MD5 object. Dim md5Hasher As MD5 = MD5.Create() ' Convert the input string to a byte array and compute the hash. Dim data As Byte() = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input)) ' Create a new Stringbuilder to collect the bytes ' and create a string. Dim sBuilder As New StringBuilder() ' Loop through each byte of the hashed data ' and format each one as a hexadecimal string. Dim i As Integer For i = 0 To data.Length - 1 sBuilder.Append(data(i).ToString("x2")) Next i ' Return the hexadecimal string. Return sBuilder.ToString() End Function Please can someone help me to make this work how I would like it to work

Jan 7th, 2006, 1:48 PM	#4
Rory Expert Programmer Join Date: Jan 2005 Location: London Posts: 542 Rep Power: 4	OK, just a few things about that code: Firstly the data should be passed as a reference type to prevent needless duplication of memory, which is important if you're hashing a relatively large amount of data. Secondly, however, if you're using this to hash entire files, you should use System.Security.Cryptography.MD5.ComputeHash with a filestream instead, and wrapper this in a callback thread so that your application does not "freeze" while the hash is being calculated, perhaps even giving user feedback. Then again if the reliability and speed are important, you might want to look for an open source optimised ASM library like OpenSSL instead, as the .NET FW's routines are written in CLR and are appallingly slow. Anyway here's your function: (Toggle Plain Text) Public Function getMd5Hash(ByRef Data As String) As String Dim md5Hasher As System.Security.Cryptography.MD5 = System.Security.Cryptography.MD5.Create() Dim Hash As Byte() = md5Hasher.ComputeHash(System.Text.Encoding.ASCII.GetBytes(Data)) Dim sBuilder As System.Text.StringBuilder = New System.Text.StringBuilder(32) For I As Integer = 0 To Hash.Length - 1 sBuilder.Append(Hash(I).ToString("x2")) Next I Return sBuilder.ToString() End Function Public Function getMd5Hash(ByRef Data As String) As String Dim md5Hasher As System.Security.Cryptography.MD5 = System.Security.Cryptography.MD5.Create() Dim Hash As Byte() = md5Hasher.ComputeHash(System.Text.Encoding.ASCII.GetBytes(Data)) Dim sBuilder As System.Text.StringBuilder = New System.Text.StringBuilder(32) For I As Integer = 0 To Hash.Length - 1 sBuilder.Append(Hash(I).ToString("x2")) Next I Return sBuilder.ToString() End Function

Feb 11th, 2006, 3:48 PM	#6
emdiesse Programmer Join Date: Jul 2004 Location: Hampshire Posts: 56 Rep Power: 5	Ahah. Done it. I would now like to know how to change the length of the the output of my Md5 hash. I would like it to be possible to make it longer or shorter by the use of another text box. How do I do this? Do the numbers have to be base 2 (2,4,8,16,32,64,etc), or can they be any integer? I have changed the code to this: (Toggle Plain Text) Imports System Imports System.Security.Cryptography Imports System.Text Module Generate Public Function getMd5Hash(ByRef Data As String) As String Dim md5Hasher As System.Security.Cryptography.MD5 = System.Security.Cryptography.MD5.Create() Dim Hash As Byte() = md5Hasher.ComputeHash(System.Text.Encoding.ASCII.GetBytes(Data)) Dim sBuilder As System.Text.StringBuilder = New System.Text.StringBuilder(32) For I As Integer = 0 To Hash.Length - 1 sBuilder.Append(Hash(I).ToString("x2")) Next I Return sBuilder.ToString() End Function End Module Public Class frmMd5 Inherits System.Windows.Forms.Form Private Sub btnGen_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGen.Click Dim source As String source = txtOne.Text & txtTwo.Text Dim hash As String = getMd5Hash(source) txtEnc.Text = hash End Sub End Class Imports System Imports System.Security.Cryptography Imports System.Text Module Generate Public Function getMd5Hash(ByRef Data As String) As String Dim md5Hasher As System.Security.Cryptography.MD5 = System.Security.Cryptography.MD5.Create() Dim Hash As Byte() = md5Hasher.ComputeHash(System.Text.Encoding.ASCII.GetBytes(Data)) Dim sBuilder As System.Text.StringBuilder = New System.Text.StringBuilder(32) For I As Integer = 0 To Hash.Length - 1 sBuilder.Append(Hash(I).ToString("x2")) Next I Return sBuilder.ToString() End Function End Module Public Class frmMd5 Inherits System.Windows.Forms.Form Private Sub btnGen_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGen.Click Dim source As String source = txtOne.Text & txtTwo.Text Dim hash As String = getMd5Hash(source) txtEnc.Text = hash End Sub End Class Thanks.

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Jan 6th, 2006, 5:41 PM	#2
Polyphemus_ Expert Programmer Join Date: Aug 2005 Location: Rotterdam, the Netherlands Posts: 942 Rep Power: 4	Please tell us what doesn't work, or what works wrong. We are quite good at programming, but we fail miserably at mind reading.

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