/// <summary>
/// Decrypts the contents of the provided PacketStream instance.
/// </summary>
/// <param name="EncryptedPacket">An encrypted PacketStream instance.</param>
/// <param name="DecryptionArgs">A DecryptionArgsContainer instance.</param>
/// <returns>A MemoryStream instance with the decrypted data.</returns>
public override MemoryStream DecryptPacket(PacketStream EncryptedPacket, DecryptionArgsContainer DecryptionArgs)
{
byte[] EncryptedData = new byte[EncryptedPacket.Length - (int)PacketHeaders.ENCRYPTED];
EncryptedPacket.Read(EncryptedData, 0, EncryptedData.Length);
byte[] DecryptedData = StaticStaticDiffieHellman.Decrypt(m_PrivateKey,
ECDiffieHellmanCngPublicKey.FromByteArray(m_PublicKey, CngKeyBlobFormat.EccPublicBlob),
m_NOnce, EncryptedData);
return(new MemoryStream(DecryptedData));
}
/// <summary>
/// Constructs an encrypted packet.
/// </summary>
/// <param name="PacketID">The ID of the packet.</param>
/// <param name="PacketData">The data to encrypt.</param>
/// <returns>A byte array containing the ID, length of the encrypted data and the encrypted data.</returns>
public override byte[] FinalizePacket(byte PacketID, byte[] PacketData)
{
MemoryStream PacketStream = new MemoryStream();
BinaryWriter PacketWriter = new BinaryWriter(PacketStream);
PacketWriter.Write(PacketID);
byte[] EncryptedData = StaticStaticDiffieHellman.Encrypt(m_PrivateKey,
ECDiffieHellmanCngPublicKey.FromByteArray(m_PublicKey, CngKeyBlobFormat.EccPublicBlob),
m_NOnce, PacketData);
//The length of the encrypted data can be longer or smaller than the original length,
//so write the length of the encrypted data.
PacketWriter.Write((uint)(PacketHeaders.ENCRYPTED + EncryptedData.Length));
//Also write the length of the unencrypted data.
PacketWriter.Write(PacketData.Length);
PacketWriter.Flush();
PacketWriter.Write(EncryptedData);
PacketWriter.Flush();
return(PacketStream.ToArray());
}
