public static TemporaryFile SecureFileUncrypt( this ICakeContext context, FilePath file, string secret )
{
string extension = file.GetExtension();
if( extension == "enc" ) extension = file.GetFilenameWithoutExtension().GetExtension();
var f = new TemporaryFile( extension );
RijndaelCrypt.Decrypt( file.FullPath, f.Path, secret );
return f;
}