The purpose of this change is to prevent loading a defunct MD4 implementation, which exists in the Mono library in all versions prior to this path (july 2010): http://github.com/mono/mono/commit/6be3c20a61d4c9937d4b9f1e95783a6203f9f9c7 The drawback is that IF the system has a native MD4 library, it is not used. That is of course a negative thing, but so far I have not seen any stock windows/linux system with native MD4 support. git-svn-id: https://duplicati.googlecode.com/svn/trunk@481 59da171f-624f-0410-aa54-27559c288bec