Adding inner symetric encryption

client/peer.go

@@ -73,6 +73,7 @@ func (p *Peer) GetMyContact() *meowlib.ContactCard {
 	c.InvitationId = p.InvitationId
 	c.InvitationMessage = p.InvitationMessage
 	c.Name = p.MyName
+	c.SymetricKey = p.MySymKey
 	return &c
 }
 
@@ -199,6 +200,24 @@ func (p *Peer) DeserializeUserMessage(data []byte) (*meowlib.UserMessage, error)
 	return &msg, nil
 }
 
+// SymEncryptPayload applies the shared symmetric key over already-encrypted data.
+// If MySymKey is empty, data is returned unchanged (peer has no symkey configured).
+func (p *Peer) SymEncryptPayload(data []byte) ([]byte, error) {
+	if p.MySymKey == "" {
+		return data, nil
+	}
+	return meowlib.SymEncrypt(p.MySymKey, data)
+}
+
+// SymDecryptPayload removes the outer symmetric encryption layer.
+// If MySymKey is empty, data is returned unchanged.
+func (p *Peer) SymDecryptPayload(data []byte) ([]byte, error) {
+	if p.MySymKey == "" {
+		return data, nil
+	}
+	return meowlib.SymDecrypt(p.MySymKey, data)
+}
+
 // AsymEncryptMessage prepares a message to send to a specific peer contact
 func (p *Peer) AsymEncryptMessage(Message []byte) (*meowlib.EncryptedMessage, error) {
 	var enc *meowlib.EncryptedMessage
@@ -259,19 +278,29 @@ func (p *Peer) ProcessOutboundUserMessage(usermessage *meowlib.UserMessage) (*me
 	if err != nil {
 		return nil, err
 	}
-	// Encrypting it
+	// Asymmetric encryption + signature (inner layer)
 	enc, err := p.AsymEncryptMessage(serializedMessage)
 	if err != nil {
 		return nil, err
 	}
+	// Symmetric encryption (outer layer, if symkey is configured)
+	symEncrypted, err := p.SymEncryptPayload(enc.Data)
+	if err != nil {
+		return nil, err
+	}
 	// Packing it
-	packedMsg := p.PackUserMessage(enc.Data, enc.Signature)
+	packedMsg := p.PackUserMessage(symEncrypted, enc.Signature)
 	return packedMsg, nil
 }
 
 // ProcessInboundUserMessage is a helper function that decrypts and deserializes a user message
 func (p *Peer) ProcessInboundUserMessage(message []byte, signature []byte) (*meowlib.UserMessage, error) {
-	dec, err := p.AsymDecryptMessage(message, signature)
+	// Symmetric decryption (outer layer, if symkey is configured)
+	symDecrypted, err := p.SymDecryptPayload(message)
+	if err != nil {
+		return nil, err
+	}
+	dec, err := p.AsymDecryptMessage(symDecrypted, signature)
 	if err != nil {
 		return nil, err
 	}