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;
}