private MemoryStream GetStreamFromPackage(IStorage storage, ExcelEncryption encryption)
        {
            MemoryStream ret=null;        
            comTypes.STATSTG statstg;
            
            storage.Stat(out statstg, (uint)STATFLAG.STATFLAG_DEFAULT);

            IEnumSTATSTG pIEnumStatStg = null;
            storage.EnumElements(0, IntPtr.Zero, 0, out pIEnumStatStg);

            comTypes.STATSTG[] regelt = { statstg };
            uint fetched = 0;
            uint res = pIEnumStatStg.Next(1, regelt, out fetched);

            //if (regelt[0].pwcsName == "DataSpaces")
            //{
            //    PrintStorage(storage, regelt[0],"");
            //}
            if (res == 0)
            {
                byte[] data;
                EncryptionInfo encryptionInfo = null;
                while (res != 1)
                {
                    switch (statstg.pwcsName)
                    {
                        case "EncryptionInfo":
                            data = GetOleStream(storage, statstg);
                            //File.WriteAllBytes(@"c:\temp\EncInfo1.bin", data);
                            encryptionInfo = new EncryptionInfo();
                            encryptionInfo.ReadBinary(data);

                            encryption.Algorithm = encryptionInfo.Header.AlgID == AlgorithmID.AES128 ? 
                                EncryptionAlgorithm.AES128 :
                            encryptionInfo.Header.AlgID == AlgorithmID.AES192 ? 
                                EncryptionAlgorithm.AES192 : 
                                EncryptionAlgorithm.AES256;
                            break;
                        case "EncryptedPackage":
                            data = GetOleStream(storage, statstg);
                            ret = DecryptDocument(data, encryptionInfo, encryption.Password);
                            break;
                    }

                    if ((res = pIEnumStatStg.Next(1, regelt, out fetched)) != 1)
                    {
                        statstg = regelt[0];
                    }
                }
            }
            Marshal.ReleaseComObject(pIEnumStatStg);
            return ret;
        }