private void FinishEncryption()
{
TEncryptionParameters EncParams = GetEncryptionParams(Protection);
AesManaged EncEngine = TEncryptionUtils.CreateEngine(EncParams);
TAgileEncryptionKey DataKey = TAgileEncryptionKey.CreateForWriting(null, EncEngine.KeySize / 8);
DataKey.Key = TEncryptionUtils.GetRandom(DataKey.KeySizeInBytes);
TAgileEncryptionKey KeyKey = TAgileEncryptionKey.CreateForWriting(Protection.OpenPassword, EncEngine.KeySize / 8);
byte[] WorkLen = new byte[8];
BitOps.SetCardinal(WorkLen, 0, WorkingStream.Length - WorkStreamZeroPos);
EncryptStream(EncEngine, DataKey, WorkLen);
using (MemoryStream ms = new MemoryStream())
{
using (TOle2File Ole2File = new TOle2File(GetEmptyEncryptedFile()))
{
Ole2File.PrepareForWrite(ms, XlsxConsts.EncryptionInfoString, new string[0]);
CreateInfoStream(Ole2File, EncEngine, EncParams, KeyKey, DataKey);
}
ms.Position = 0;
using (TOle2File Ole2File = new TOle2File(ms))
{
Ole2File.PrepareForWrite(TargetStream, XlsxConsts.ContentString, new string[0]);
WorkingStream.Position = 0;
TEncryptionUtils.CopyStream(WorkingStream, Ole2File);
}
}
}
public static TAgileEncryptionKey CreateForWriting(string aPassword, int KeySizeInBytes)
{
const int SaltSize = 16;
TAgileEncryptionKey Result = new TAgileEncryptionKey();
Result.SpinCount = 100000;
Result.BlockSize = 16;
Result.KeySizeInBytes = KeySizeInBytes;
Result.Salt = TEncryptionUtils.GetRandom(SaltSize);
if (aPassword != null)
{
Result.Password = Encoding.Unicode.GetBytes(aPassword);
Result.PreCalcKey();
}
return(Result);
}
private static Stream ReadAgileEncryptionInfo(TOle2File DataStream, TEncryptionData Encryption)
{
byte[] Enc = new byte[DataStream.Length - DataStream.Position];
DataStream.Read(Enc, Enc.Length);
TEncryptionParameters DataEncParams = new TEncryptionParameters();
TAgileEncryptionKey DataKey = new TAgileEncryptionKey();
TAgileEncryptionVerifier KeyVerifier = new TAgileEncryptionVerifier();
TEncryptionParameters KeyEncParams = new TEncryptionParameters();
TAgileEncryptionKey KeyKey = new TAgileEncryptionKey();
using (MemoryStream ms = new MemoryStream(Enc))
{
using (XmlReader xml = XmlReader.Create(ms))
{
xml.ReadStartElement("encryption"); //goes to keyData
ReadAgileCipherParams(xml, DataEncParams, DataKey);
xml.ReadStartElement("keyData"); //goes to dataIntegrity
//We are not checking data integrity at the moment.
//DataIntegrity.EncryptedHMacKey = Convert.FromBase64String(xml.GetAttribute("encryptedHmacKey"));
//DataIntegrity.EncryptedHmacValue = Convert.FromBase64String(xml.GetAttribute("encryptedHmacValue"));
xml.ReadStartElement("dataIntegrity"); //goes to keyEncryptors
xml.ReadStartElement("keyEncryptors"); //goes to keyEncryptor
xml.ReadStartElement("keyEncryptor"); //goes to encryptedKey
KeyKey.SpinCount = Convert.ToInt32(xml.GetAttribute("spinCount"), CultureInfo.InvariantCulture);
ReadAgileCipherParams(xml, KeyEncParams, KeyKey);
KeyVerifier.EncryptedVerifierHashInput = Convert.FromBase64String(xml.GetAttribute("encryptedVerifierHashInput"));
KeyVerifier.EncryptedVerifierHashValue = Convert.FromBase64String(xml.GetAttribute("encryptedVerifierHashValue"));
KeyVerifier.EncryptedKeyValue = Convert.FromBase64String(xml.GetAttribute("encryptedKeyValue"));
}
}
CheckPassword(Encryption, KeyVerifier, KeyEncParams, KeyKey);
DataKey.Key = KeyKey.Key;
DataKey.Password = KeyKey.Password;
DataKey.CalcDataIV(0);
return(DecryptStream(DataStream, DataEncParams, DataKey));
}
private static void WriteAgileCipherParams(XmlWriter xml, TEncryptionParameters EncParams, TAgileEncryptionKey Key)
{
xml.WriteAttributeString("saltSize", Convert.ToString(Key.Salt.Length, CultureInfo.InvariantCulture));
xml.WriteAttributeString("blockSize", Convert.ToString(Key.BlockSize, CultureInfo.InvariantCulture));
xml.WriteAttributeString("keyBits", Convert.ToString(Key.KeySizeInBytes * 8, CultureInfo.InvariantCulture));
xml.WriteAttributeString("hashSize", Convert.ToString(Key.HashSizeBytes(), CultureInfo.InvariantCulture)); //sha1 hash size
xml.WriteAttributeString("cipherAlgorithm", "AES");
switch (EncParams.ChainingMode)
{
case CipherMode.CBC:
xml.WriteAttributeString("cipherChaining", "ChainingModeCBC");
break;
case CipherMode.CFB:
xml.WriteAttributeString("cipherChaining", "ChainingModeCFB");
break;
case CipherMode.CTS:
case CipherMode.ECB:
case CipherMode.OFB:
default:
XlsMessages.ThrowException(XlsErr.ErrNotSupportedEncryption); break;
}
xml.WriteAttributeString("hashAlgorithm", "SHA1");
xml.WriteAttributeString("saltValue", Convert.ToBase64String(Key.Salt));
}
private byte[] GetInfoStreamXml(AesManaged EncEngine, TEncryptionParameters EncParams, TAgileEncryptionKey KeyKey, TAgileEncryptionKey DataKey)
{
const string KeyEncryptorPasswordNamespace = "http://schemas.microsoft.com/office/2006/keyEncryptor/password";
using (MemoryStream ms = new MemoryStream())
{
XmlWriterSettings Settings = new XmlWriterSettings();
Settings.Encoding = new System.Text.UTF8Encoding(false);
using (XmlWriter xml = XmlWriter.Create(ms, Settings))
{
xml.WriteStartDocument(true);
xml.WriteStartElement("encryption", "http://schemas.microsoft.com/office/2006/encryption");
xml.WriteAttributeString("xmlns", "p", null, KeyEncryptorPasswordNamespace);
xml.WriteStartElement("keyData");
WriteAgileCipherParams(xml, EncParams, DataKey);
xml.WriteEndElement();
xml.WriteStartElement("dataIntegrity");
byte[] HMacKeyBlockKey = new byte[] { 0x5f, 0xb2, 0xad, 0x01, 0x0c, 0xb9, 0xe1, 0xf6 };
DataKey.CalcDataIV(HMacKeyBlockKey);
byte[] HMacKey = TEncryptionUtils.GetRandom((int)DataKey.HashSizeBytes());
using (ICryptoTransform Encryptor = EncEngine.CreateEncryptor(DataKey.Key, DataKey.IV))
{
byte[] EncryptedHMacKey = TAgileEncryptionVerifier.EncryptBytes(HMacKey, Encryptor, DataKey.BlockSize);
xml.WriteAttributeString("encryptedHmacKey", Convert.ToBase64String(EncryptedHMacKey));
}
HMAC HMacCalc = new HMACSHA1(HMacKey);
WorkingStream.Position = 0;
byte[] HMac = HMacCalc.ComputeHash(WorkingStream);
byte[] HMacValBlockKey = new byte[] { 0xa0, 0x67, 0x7f, 0x02, 0xb2, 0x2c, 0x84, 0x33 };
DataKey.CalcDataIV(HMacValBlockKey);
using (ICryptoTransform Encryptor = EncEngine.CreateEncryptor(DataKey.Key, DataKey.IV))
{
byte[] EncryptedHMacValue = TAgileEncryptionVerifier.EncryptBytes(HMac, Encryptor, DataKey.BlockSize);
xml.WriteAttributeString("encryptedHmacValue", Convert.ToBase64String(EncryptedHMacValue));
}
xml.WriteEndElement();
xml.WriteStartElement("keyEncryptors");
xml.WriteStartElement("keyEncryptor");
xml.WriteAttributeString("uri", KeyEncryptorPasswordNamespace);
xml.WriteStartElement("encryptedKey", KeyEncryptorPasswordNamespace);
xml.WriteAttributeString("spinCount", Convert.ToString(KeyKey.SpinCount, CultureInfo.InvariantCulture));
WriteAgileCipherParams(xml, EncParams, KeyKey);
byte[] RandData = TEncryptionUtils.GetRandom(KeyKey.Salt.Length);
KeyKey.CalcKey(TAgileEncryptionKey.VerifierHashInputBlockKey, null);
using (ICryptoTransform Encryptor = EncEngine.CreateEncryptor(KeyKey.Key, KeyKey.IV))
{
byte[] EncryptedVerifierHashInput = TAgileEncryptionVerifier.EncryptBytes(RandData, Encryptor, KeyKey.BlockSize);
xml.WriteAttributeString("encryptedVerifierHashInput", Convert.ToBase64String(EncryptedVerifierHashInput));
}
KeyKey.CalcKey(TAgileEncryptionKey.VerifierHashValueBlockKey, null);
using (ICryptoTransform Encryptor = EncEngine.CreateEncryptor(KeyKey.Key, KeyKey.IV))
{
byte[] EncryptedVerifierHashValue = TAgileEncryptionVerifier.EncryptBytes(KeyKey.Hash(RandData), Encryptor, KeyKey.BlockSize);
xml.WriteAttributeString("encryptedVerifierHashValue", Convert.ToBase64String(EncryptedVerifierHashValue));
}
KeyKey.CalcKey(TAgileEncryptionKey.VerifierKeyValueBlockKey, null);
using (ICryptoTransform Encryptor = EncEngine.CreateEncryptor(KeyKey.Key, KeyKey.IV))
{
byte[] EncryptedKeyValue = TAgileEncryptionVerifier.EncryptBytes(DataKey.Key, Encryptor, KeyKey.BlockSize);
xml.WriteAttributeString("encryptedKeyValue", Convert.ToBase64String(EncryptedKeyValue));
}
xml.WriteEndElement();
xml.WriteEndElement();
xml.WriteEndElement();
xml.WriteEndElement();
xml.WriteEndDocument();
}
return(ms.ToArray());
}
}
private void CreateInfoStream(TOle2File DataStream, AesManaged EncEngine, TEncryptionParameters EncParams, TAgileEncryptionKey KeyKey, TAgileEncryptionKey DataKey)
{
DataStream.Write16(0x0004);
DataStream.Write16(0x0004);
DataStream.Write32(0x00040);
byte[] InfoStreamXml = GetInfoStreamXml(EncEngine, EncParams, KeyKey, DataKey);
DataStream.Write(InfoStreamXml, InfoStreamXml.Length);
byte[] pad = new byte[4098 - InfoStreamXml.Length]; //Our Ole2 implementation will fill a sector with 0 so it doesn't go to the ministream. Those 0 will confuse Excel, so we will write spaces.
for (int i = 0; i < pad.Length; i++)
{
pad[i] = 32;
}
DataStream.Write(pad, pad.Length);
}
