/// <summary>
/// Method for decrypting an extracted watermark.
/// </summary>
/// <param name="password">The password that was used during encryption.</param>
public Watermark Decrypt(string password)
{
bytes = new Rfc2898DeriveBytes(password, salt);
this.key = bytes.GetBytes(Algorithm.KeySize / 8);
Algorithm.Key = key;
int ivLength = BitConverter.ToInt32(cryptedData, 0);
byte[] iv = new byte[ivLength];
Array.Copy(cryptedData, 4, iv, 0, ivLength);
Algorithm.IV = iv;
int cryptDataLength = BitConverter.ToInt32(cryptedData, 4 + ivLength);
byte[] cryptedData2 = new byte[cryptDataLength];
Array.Copy(cryptedData, 4 + ivLength + 4, cryptedData2, 0, cryptDataLength);
byte[] decrypted = Decrypt(cryptedData2, Algorithm);
byte markType = decrypted[0];
int markDataLength = BitConverter.ToInt32(decrypted, 1);
byte[] markData = new byte[markDataLength];
Array.Copy(decrypted, 5, markData, 0, markDataLength);
Watermark decryptedMark = null;
switch (markType)
{
case 1:
decryptedMark = TextWatermark.LoadFromBytes(markData);
break;
case 2:
decryptedMark = FileWatermark.LoadFromBytes(markData);
break;
case 3:
decryptedMark = BinaryWatermark.LoadFromBytes(markData);
break;
case 4:
decryptedMark = CompositeWatermark.LoadFromBytes(markData);
break;
case 9:
decryptedMark = EncryptedWatermark.LoadFromBytes(markData);
break;
}
return(decryptedMark);
}
internal static EncryptedWatermark LoadFromBytes(byte[] data)
{
int saltLength = BitConverter.ToInt32(data, 0);
byte[] salt = new byte[saltLength];
Array.Copy(data, 4, salt, 0, saltLength);
int cryptedChunkLength = BitConverter.ToInt32(data, 4 + saltLength);
byte[] cryptedChunk = new byte[cryptedChunkLength];
Array.Copy(data, 4 + saltLength + 4, cryptedChunk, 0, cryptedChunkLength);
EncryptedWatermark mark = new EncryptedWatermark(cryptedChunk, salt);
return(mark);
}
internal static CompositeWatermark LoadFromBytes(byte[] data)
{
CompositeWatermark comp = new CompositeWatermark();
MemoryStream ms = new MemoryStream(data);
byte[] type = new byte[1];
byte[] dword = new byte[4];
byte[] markData;
while (ms.Position < ms.Length)
{
ms.Read(type, 0, 1);
ms.Read(dword, 0, 4);
markData = new byte[BitConverter.ToInt32(dword, 0)];
ms.Read(markData, 0, markData.Length);
Watermark mark = null;
switch (type[0])
{
case 1:
mark = TextWatermark.LoadFromBytes(markData);
break;
case 2:
mark = FileWatermark.LoadFromBytes(markData);
break;
case 3:
mark = BinaryWatermark.LoadFromBytes(markData);
break;
case 4:
mark = CompositeWatermark.LoadFromBytes(markData);
break;
case 9:
mark = EncryptedWatermark.LoadFromBytes(markData);
break;
}
comp.watermarks.Add(mark);
}
return(comp);
}