public static MessageModel EncryptMessage(this MessageModel message)
{
if (message.Recipient != null && message.Recipient.PublicKey == null)
{
return(message);
}
// Serialize the message
MemoryStream stream = new MemoryStream();
ProtoBuf.Serializer.Serialize <MessageModel>(stream, message);
// Encrypt it using AES
byte[] aesKey;
byte[] encryptedSerializedMessage = AesEncryption.EncryptMessage(stream.ToArray(), out aesKey);
// Encrypt the AES key using sender's Public Key and recipient's public key
byte[] senderEncryptedKey = RsaEncryption.EncryptMessage(aesKey, message.Sender.PublicKey);
byte[] recipientEncryptedKey = RsaEncryption.EncryptMessage(aesKey, message.Recipient.PublicKey);
// Put them together to create an encrypted message
MemoryStream encryptedMessageBytes = new MemoryStream();
encryptedMessageBytes.WriteBlob(recipientEncryptedKey);
encryptedMessageBytes.WriteBlob(senderEncryptedKey);
encryptedMessageBytes.WriteBlob(encryptedSerializedMessage);
// Copy only the minimal amount of data
MessageModel encryptedMessage = new MessageModel();
encryptedMessage.EncryptedMessage = encryptedMessageBytes.ToArray();
encryptedMessage.MessageFlags = MessageFlags.EncryptedMessage;
message.CopyNonEncryptedProperties(encryptedMessage);
encryptedMessage.ClientMessageId = message.ClientMessageId;
return(encryptedMessage);
}