Visual Basic

    Private Const ALG_CLASS_HASH As Long = 32768             ' (4 < 13)
    Private Const ALG_TYPE_ANY As Long = 0
    Private Const ALG_SID_MD5 As Long = 3
    Private Const CALG_MD5 As Long = ALG_CLASS_HASH Or ALG_TYPE_ANY Or ALG_SID_MD5

    ....

    Private Declare Function CryptAcquireContext Lib "advapi32.dll" Alias "CryptAcquireContextA" _
    (ByRef phProv As Long, _
    ByVal pszContainer As String, _
    ByVal pszProvider As String, _
    ByVal dwProvType As Long, _
    ByVal dwFlags As Long) As Long

Private Declare Function CryptCreateHash Lib "advapi32.dll" _
    (ByVal hProv As Long, _
    ByVal algID As Long, _
    ByVal hKey As Long, _
    ByVal dwFlags As Long, _
    ByRef phHash As Long) As Long
    ...

    'CryptAcquireContext works fine
    lResult = CryptAcquireContext(m_lProvider, sKeyRoot, CRYPTO_PROVIDER, PROV_RSA_FULL, 0)
    If lResult = 0 Then
        lResult = CryptAcquireContext(m_lProvider, sKeyRoot, CRYPTO_PROVIDER, PROV_RSA_FULL, CRYPT_NEWKEYSET)
        If lResult = 0 Then
            MsgBox(ERROR_AQUIRING_CONTEXT)
        End If
    End If


    'Now this is where I get zero
    ' Create a handle to a hash object  using the MD5 algorithm
    lResult = CryptCreateHash(m_lProvider, CALG_MD5, 0, 0, lHash)
    If lResult = 0 Then
        Dim a As Long = Err.LastDllError
        MsgBox(ERROR_CREATING_HASH)
        Return ""
    End If

<StructLayout(LayoutKind.Sequential, Pack:=1)> _
 Public Structure FILEHEADER
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=4)> Dim magic As String
    Dim offset As UInt32
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=8)> Dim version As String
    Dim fileSize As UInt32
    Dim dittoKey As UInt32
    Dim genericSize As UInt32
    Dim industrySize As UInt32
    Dim userSize As UInt32
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=100)> Dim fileName As String
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=24)> Dim timedate As String
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=100)> Dim creator As String
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=200)> Dim project As String
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=200)> Dim copyright As String
    Dim encryptKey As UInt32
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=104)> Dim Reserved As String
End Structure

Sub Main()
    Dim fh As FILEHEADER = New FILEHEADER
    ByteArray = GetBytesFromFile(myFile)
    Dim MyGC As GCHandle = GCHandle.Alloc(ByteArray, GCHandleType.Pinned)
    fh = DirectCast(Marshal.PtrToStructure(MyGC.AddrOfPinnedObject, GetType(FILEHEADER)), FILEHEADER)
    MyGC.Free()

    Console.WriteLine("Magic:" & fh.magic)
    Console.WriteLine("Offset:" & fh.offset)
    Console.WriteLine("Version:" & fh.version)
    Console.WriteLine("File Size:" & fh.fileSize)
    Console.WriteLine("Ditto Key:" & fh.dittoKey)
    Console.WriteLine("Generic Size:" & fh.genericSize)
    Console.WriteLine("Industry Size:" & fh.industrySize)
    Console.WriteLine("User Size:" & fh.userSize)
    Console.WriteLine("File Name:" & fh.fileName)
    Console.WriteLine("Time-Date:" & fh.timedate)
    Console.WriteLine("Creator:" & fh.creator)
    Console.WriteLine("Project:" & fh.project)
    Console.WriteLine("Copyright:" & fh.copyright)
    Console.WriteLine("Encrypt Key:" & fh.encryptKey)
    Console.WriteLine("Reserved:" & fh.Reserved)
    Console.WriteLine(StrDup(30, "-"))
    'Console.WriteLine("actFlatAct:" & String.Concat((From s In fh.ActFlatAct Select s.ToString("f2") & " ").ToArray))
    Console.WriteLine("FILEHEADER size:" & Marshal.SizeOf(fh))
    Console.ReadKey()

End Sub