Shorten a string containing data - vb.net

Question

I am creating an application to create a key that is unique to each computer. This info is derived from the OS serial number and processorID.
Is there a way to 'shorten' a string? Maybe by converting it to HEX or something else...
The reason is this: I used to use a VB6 section of code (http://www.planet-source-code.com/vb...48926&lngWId=1) that gets the details and the output is only 13 digits long. Mine is a lot longer, but gets the same info...
BTW, the link I posted above won multiple awards, but I am having huge trouble in converting it to .NET. Has anyone by any chance converted it, or know of someone who has? Or a tool that actually works?
Thanks
EDIT
Here is the full working link: http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=48926&lngWId=1

Answer 1

It sounds like you want a 'hashing algorithm' or 'hash function'. They are a common concept: http://en.wikipedia.org/wiki/Hash_function
Generally speaking you can simply write your own function to take a string and return a hashed number but there is some suitable code here that uses the .NET framework: http://support.microsoft.com/kb/301053

Answer 2

Here is a working example which retrieves the Processor ID, for the first Processor found, and the OS Serial Number; it concatenates these to strings together and then performs various encodings on them.
This is a simple VB.Net Console project. Be sure to reference the System.Management assembly in your project. Just copy and paste this code example into the main module, set a breakpoint at the end of Sub Main(), and look at the various results.
Module Module1
Sub Main()
Dim uniqueID As String = GetUniqueID()
' convert it to a base64 string
Dim encoding As New Text.ASCIIEncoding()
Dim result1 = Convert.ToBase64String(encoding.GetBytes(uniqueID))
' compress it
Dim result2 As String = CompressString(uniqueID)
Dim result3 As String = DecompressString(result2)
' encrypt it
Dim result4 As String = AES_Encrypt(uniqueID, "password")
Dim result5 As String = AES_Decrypt(result4, "password")
' hash it
Dim result6 As String = HashString(uniqueID)
End Sub
Private Function GetUniqueID() As String
Dim result As String = GetOSSerialNumber()
Dim processorIDs() As String = GetProcessorIDs()
If ((processorIDs IsNot Nothing) AndAlso (processorIDs.Count > 0)) Then
result &= processorIDs(0)
End If
Return result
End Function
Private Function GetProcessorIDs() As String()
Dim result As New List(Of String)
Dim searcher = New System.Management.ManagementObjectSearcher("Select ProcessorId from Win32_Processor")
For Each managementObj In searcher.Get()
result.Add(CStr(managementObj.Properties("ProcessorId").Value))
Next
Return result.ToArray()
End Function
Private Function GetOSSerialNumber() As String
Dim result As String = ""
Dim searcher = New System.Management.ManagementObjectSearcher("Select SerialNumber from Win32_OperatingSystem")
For Each managementObj In searcher.Get()
result = CStr(managementObj.Properties("SerialNumber").Value)
Next
Return result
End Function
Public Function CompressString(ByVal source As String) As String
Dim result As String = ""
Dim encoding As New Text.ASCIIEncoding()
Dim bytes() As Byte = encoding.GetBytes(source)
Using ms As New IO.MemoryStream
Using gzsw As New System.IO.Compression.GZipStream(ms, IO.Compression.CompressionMode.Compress)
gzsw.Write(bytes, 0, bytes.Length)
gzsw.Close()
result = Convert.ToBase64String(ms.ToArray)
End Using
End Using
Return result
End Function
Public Function DecompressString(ByVal source As String) As String
Dim result As String = ""
Dim bytes() As Byte = Convert.FromBase64String(source)
Using ms As New IO.MemoryStream(bytes)
Using gzsw As New System.IO.Compression.GZipStream(ms, IO.Compression.CompressionMode.Decompress)
Dim data(CInt(ms.Length)) As Byte
gzsw.Read(data, 0, CInt(ms.Length))
Dim encoding As New Text.ASCIIEncoding()
result = encoding.GetString(data)
End Using
End Using
Return result
End Function
Public Function AES_Encrypt(ByVal input As String, ByVal pass As String) As String
Dim AES As New System.Security.Cryptography.RijndaelManaged
Dim Hash_AES As New System.Security.Cryptography.MD5CryptoServiceProvider
Dim encrypted As String = ""
Try
Dim hash(31) As Byte
Dim temp As Byte() = Hash_AES.ComputeHash(System.Text.ASCIIEncoding.ASCII.GetBytes(pass))
Array.Copy(temp, 0, hash, 0, 16)
Array.Copy(temp, 0, hash, 15, 16)
AES.Key = hash
AES.Mode = Security.Cryptography.CipherMode.ECB
Dim DESEncrypter As System.Security.Cryptography.ICryptoTransform = AES.CreateEncryptor
Dim Buffer As Byte() = System.Text.ASCIIEncoding.ASCII.GetBytes(input)
encrypted = Convert.ToBase64String(DESEncrypter.TransformFinalBlock(Buffer, 0, Buffer.Length))
Catch ex As Exception
End Try
Return encrypted
End Function
Public Function AES_Decrypt(ByVal input As String, ByVal pass As String) As String
Dim AES As New System.Security.Cryptography.RijndaelManaged
Dim Hash_AES As New System.Security.Cryptography.MD5CryptoServiceProvider
Dim decrypted As String = ""
Try
Dim hash(31) As Byte
Dim temp As Byte() = Hash_AES.ComputeHash(System.Text.ASCIIEncoding.ASCII.GetBytes(pass))
Array.Copy(temp, 0, hash, 0, 16)
Array.Copy(temp, 0, hash, 15, 16)
AES.Key = hash
AES.Mode = Security.Cryptography.CipherMode.ECB
Dim DESDecrypter As System.Security.Cryptography.ICryptoTransform = AES.CreateDecryptor
Dim Buffer As Byte() = Convert.FromBase64String(input)
decrypted = System.Text.ASCIIEncoding.ASCII.GetString(DESDecrypter.TransformFinalBlock(Buffer, 0, Buffer.Length))
Catch ex As Exception
End Try
Return decrypted
End Function
Private Function HashString(ByVal source As String) As String
Dim encoding As New Text.ASCIIEncoding()
Dim bytes() As Byte = encoding.GetBytes(source)
Dim workingHash() As Byte = New System.Security.Cryptography.MD5CryptoServiceProvider().ComputeHash(bytes)
Dim result As String = ""
For Each b In workingHash
result = result & b.ToString("X2")
Next
Return result
End Function
End Module