I forked the code and downloaded it and MD5.CS is missing from the project. The proj file has a reference but it is not been included.
Comments: The code for MD5.cs is available here: http://www.jeff.wilcox.name/2008/03/silverlight-2-md5/ Not sure if excluding it is by design (licensing issues?) or just mistake.
Comments: The code for MD5.cs is available here: http://www.jeff.wilcox.name/2008/03/silverlight-2-md5/ Not sure if excluding it is by design (licensing issues?) or just mistake.