to retrieve,
byte[] bs = (byte[])cacheManager.GetData(strKey);
//decrypt...
MemoryStream ms = new MemoryStream(bs);
DataSet ds = new DataSet();
ds.ReadXml(ms);
also, you might want to look into Enterprise Library
http://msdn.microsoft.com/library/en-us/dnpag2/html/entlib.asp?frame=true