Why is a System.ArgumentException occurring on the second or third iteration of a cryptographic line of code?

Question

I'm getting the following error after executing code that deals with cryptography:

An unhandled exception of type 'System.ArgumentException' occurred in mscorlib.dll Additional information: Object of type 'System.Int64' cannot be converted to type 'System.UInt32'.

A few sources (e.g. http://truncatedcodr.wordpress.com/2012/06/20/fix-sitecore-and-net-framework-4-5/ ) where a similar error occurred say to change a value to the following in Web.config (pardon the space after the "less than" sign):

< setting name=”Login.RememberLastLoggedInUserName” value=”false” />

I have never used a Web.config file before, so this could be the solution. However, my project doesn't have one (I'm not sure if it could have one since I don't think it has a web site name) and I don't know why there were apparent successes in the previous iteration(s). Anyway, here is the portion of my code that contains the problem (I took out some irrelevant code):

Dim stream As IO.FileStream Dim dataOffset As Int64 Dim dataSize As Int64 Dim del2 As New ChangeProgress2Delegate(AddressOf ChangeProgress2)

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
    Dim fileDialog As New OpenFileDialog()
    fileDialog.ShowDialog()
    stream = New IO.FileStream(fileDialog.FileName, IO.FileMode.Open, IO.FileAccess.ReadWrite)
    Dim t As New Threading.Tasks.Task(AddressOf Perform)
    t.Start()
End Sub

Public Sub Perform()
    Dim Key(15) As [Byte]
    Dim Bytes(15) As [Byte]
    Dim IV(15) As [Byte]
    Dim userData(31743) As [Byte]
    Dim encryption2 As Security.Cryptography.Aes
    Dim decryptor2 As Security.Cryptography.ICryptoTransform
    Dim msDecrypt2 As IO.MemoryStream
    Dim csDecrypt2 As Security.Cryptography.CryptoStream
    For i As UInt32 = 0 To 3
        .
        .
        .
        For j As UInt32 = 0 To (numPartitions - 1)
            .
            .
            .
            dataOffset = Convert.ToUInt32((Convert.ToUInt64(stream.ReadByte()) << 24) + (Convert.ToUInt64(stream.ReadByte()) << 16) + (Convert.ToUInt64(stream.ReadByte()) << 8) + Convert.ToUInt64(stream.ReadByte())) >> 2
            dataSize = Convert.ToUInt32((Convert.ToUInt64(stream.ReadByte()) << 24) + (Convert.ToUInt64(stream.ReadByte()) << 16) + (Convert.ToUInt64(stream.ReadByte()) << 8) + Convert.ToUInt64(stream.ReadByte())) >> 2
            stream.Position = dataOffset
            For k = 0 To ((dataSize / 32768) - 1)
                stream.Position += 976
                stream.Read(IV, 0, 16)
                stream.Position += 32
                stream.Read(userData, 0, 31744)
                encryption2 = Security.Cryptography.Aes.Create()
                encryption2.Key = Key
                encryption2.IV = IV
                encryption2.Padding = Security.Cryptography.PaddingMode.None
                decryptor2 = encryption2.CreateDecryptor(encryption2.Key, encryption2.IV)
                msDecrypt2 = New IO.MemoryStream(userData)
                csDecrypt2 = New Security.Cryptography.CryptoStream(msDecrypt2, decryptor2, Security.Cryptography.CryptoStreamMode.Read)
                csDecrypt2.Read(userData, 0, 31744)
                stream.Position -= 31744
                stream.Write(userData, 0, 31744)
                Debugger.Break()
                Me.BeginInvoke(del2, {i + 1, j + 1, numPartitions})
            Next
        Next
    Next
End Sub

Public Sub ChangeProgress2(ByVal partitionOrder As UInt32, ByVal partitionNum As UInt32, ByVal numPartitions As UInt32)
    Progress.Value = ((stream.Position - dataOffset) / dataSize) * 100
End Sub

Public Delegate Sub ChangeProgress2Delegate(ByVal partitionOrder As UInt32, ByVal partitionNum As UInt32, ByVal numPartitions As UInt32)

In the code above, the error has been firing somewhat randomly between these three lines of code on the second or third iteration:

decryptor2 = encryption2.CreateDecryptor(encryption2.Key, encryption2.IV) msDecrypt2 = New IO.MemoryStream(userData) csDecrypt2 = New Security.Cryptography.CryptoStream(msDecrypt2, decryptor2, Security.Cryptography.CryptoStreamMode.Read)

Answer 1

I found the error. It didn't have to do with any cryptography even though the exception was firing around those lines of code. At the BeginInvoke line, I needed to convert the parameters into UInt32 so that code looked like:

Me.BeginInvoke(del2, {Convert.ToUInt32(i + 1), Convert.ToUInt32(j + 1), Convert.ToUInt32(numPartitions)})

I had to do this even though i was a UInt32, j was a UInt32, and numPartitions was a UInt32.