Filesystem: Add GetChecksum

Modules.Filesystem/File.vb

@@ -1,4 +1,5 @@
 Imports System.IO
+Imports System.Security.Cryptography
 Imports System.Text.RegularExpressions
 Imports DigitalData.Modules.Logging
 
@@ -65,6 +66,14 @@ Public Class File
         Return oCleanName
     End Function
 
+    Public Function GetChecksum(FilePath As String) As String
+        Using oStream As New BufferedStream(IO.File.OpenRead(FilePath), 1200000)
+            Dim oSHA As New SHA256Managed()
+            Dim oChecksum() As Byte = oSHA.ComputeHash(oStream)
+            Return BitConverter.ToString(oChecksum).Replace("-", String.Empty)
+        End Using
+    End Function
+
     ''' <summary>
     ''' Adds fileversions to given filename `Destination` if that file already exists.
     ''' </summary>