From 0b1ed3936a71430f005290957f34bdff2aeb1f22 Mon Sep 17 00:00:00 2001
From: Aviv Eyal <aviveyal07@gmail.com>
Date: Tue, 28 Nov 2017 12:28:40 +0200
Subject: [PATCH] Authenticate ping protocol messages

---
 examples/multipro/node.go | 39 +++++++++++++++++++++++++++++++++++----
 examples/multipro/ping.go | 24 ++++++++++++++++++++++--
 2 files changed, 57 insertions(+), 6 deletions(-)

diff --git a/examples/multipro/node.go b/examples/multipro/node.go
index 7771e1a4..4a633817 100644
--- a/examples/multipro/node.go
+++ b/examples/multipro/node.go
@@ -4,15 +4,44 @@ import (
 	host "gx/ipfs/QmRS46AyqtpJBsf1zmQdeizSDEzo1qkWR7rdEuPFAv8237/go-libp2p-host"
 	peer "gx/ipfs/QmXYjuNuxVzXKJCfWasQk1RqkhVLDM9jtUKhqc2WPQmFSB/go-libp2p-peer"
 	"github.com/gogo/protobuf/proto"
+
+	p2p "github.com/libp2p/go-libp2p/examples/multipro/pb"
+	"log"
 )
 
+func (n Node) authenticateMessage(message proto.Message, data *p2p.MessageData) bool {
+
+	// store a temp ref to sig and remove it from data
+	sign := data.Sign
+	data.Sign = ""
+
+	//log.Print("Signature: %s", []byte(sign))
+
+	// marshall data without the sig to binary format
+	bin, err := proto.Marshal(message)
+	if err != nil {
+		// todo: log
+		return false
+	}
+
+	// restore sig in message data (for possible future use)
+	data.Sign = sign
+
+	peerId, err := peer.IDB58Decode(data.NodeId)
+
+	if err != nil {
+		log.Fatal(err, "Failed to decode node id")
+		return false
+	}
+
+	return n.verifyData(bin, []byte(sign), peerId)
+}
+
 func (n Node) signProtoMessage(message proto.Message) ([]byte, error) {
-	// sign the data
 	data, err := proto.Marshal(message)
 	if err != nil {
 		return nil, err
 	}
-
 	return n.signData(data)
 }
 
@@ -22,8 +51,10 @@ func (n Node) signData(data []byte) ([]byte, error) {
 	return res, err
 }
 
-func (n Node) verifyData(data []byte, signature []byte, signerHostId peer.ID) bool {
-	key := n.Peerstore().PubKey(signerHostId)
+// precondition: we have info about the signer peer in the local peer store
+func (n Node) verifyData(data []byte, signature []byte, peerId peer.ID) bool {
+	key := n.Peerstore().PubKey(peerId)
+	//log.Print ("%s %s %s", peerId, key, peerId.String())
 	res, err := key.Verify(data, signature)
 	return res == true && err == nil
 }
diff --git a/examples/multipro/ping.go b/examples/multipro/ping.go
index 06d60d05..8e3bc7e7 100644
--- a/examples/multipro/ping.go
+++ b/examples/multipro/ping.go
@@ -12,6 +12,7 @@ import (
 	p2p "github.com/libp2p/go-libp2p/examples/multipro/pb"
 	protobufCodec "github.com/multiformats/go-multicodec/protobuf"
 	"gx/ipfs/QmRS46AyqtpJBsf1zmQdeizSDEzo1qkWR7rdEuPFAv8237/go-libp2p-host"
+	"gx/ipfs/QmXYjuNuxVzXKJCfWasQk1RqkhVLDM9jtUKhqc2WPQmFSB/go-libp2p-peer"
 )
 
 // pattern: /protocol-name/request-or-response-message/version
@@ -46,9 +47,19 @@ func (p PingProtocol) onPingRequest(s inet.Stream) {
 
 	log.Printf("%s: Received ping request from %s. Message: %s", s.Conn().LocalPeer(), s.Conn().RemotePeer(), data.Message)
 
+	valid := p.node.authenticateMessage(data, data.MessageData)
+
+	if !valid {
+		log.Fatal("Failed to authenticate message")
+		return
+	} else {
+		log.Print("Authenticated request content was generated by claimed node :-)")
+	}
+
 	// generate response message
 	log.Printf("%s: Sending ping response to %s. Message id: %s...", s.Conn().LocalPeer(), s.Conn().RemotePeer(), data.MessageData.Id)
-	resp := &p2p.PingResponse{MessageData: NewMessageData(p.node.ID().String(), data.MessageData.Id, false),
+
+	resp := &p2p.PingResponse{MessageData: NewMessageData(peer.IDB58Encode(p.node.ID()), data.MessageData.Id, false),
 		Message: fmt.Sprintf("Ping response from %s", p.node.ID())}
 
 	// sign the data
@@ -84,6 +95,15 @@ func (p PingProtocol) onPingResponse(s inet.Stream) {
 		return
 	}
 
+	valid := p.node.authenticateMessage(data, data.MessageData)
+
+	if !valid {
+		log.Fatal("Failed to authenticate message")
+		return
+	} else {
+		log.Print("Authenticated response content generated by claimed node :-)")
+	}
+
 	// locate request data and remove it if found
 	_, ok := p.requests[data.MessageData.Id]
 	if ok {
@@ -102,7 +122,7 @@ func (p PingProtocol) Ping(host host.Host) bool {
 	log.Printf("%s: Sending ping to: %s....", p.node.ID(), host.ID())
 
 	// create message data
-	req := &p2p.PingRequest{MessageData: NewMessageData(p.node.ID().String(), uuid.New().String(), false),
+	req := &p2p.PingRequest{MessageData: NewMessageData(peer.IDB58Encode(p.node.ID()), uuid.New().String(), false),
 		Message: fmt.Sprintf("Ping from %s", p.node.ID())}
 
 	// sign the data