Published May 19, 2017 © GPL3+

FAM

Super Secret Messaging with PocketCHIP!

IntermediateWork in progress2 hours2,704

Things used in this project

Hardware components

Pocket C.H.I.P.

C.H.I.P.

Raspberry Pi 1 Model B+

Story

The Idea

So I thought it would be cool to have a messaging service where there is kind of a decentralized server and where the message data cannot be decrypted by the server. It's kind of like a private messaging service for your family that only family members can be a part of.

I know I know, never implement your own crypto, but I had a lot of fun with this, and I think its pretty secure if you keep it running on your Local Area Network. Also, I know this is mostly a software hack, but I'm thinking in the future it could be cool to parse messages sent to the server that blinks a LED or something.

The code although functional is still being improved. There are prebuilt arm binaries to make it a little less painful to get going.

Anyway, blah blah, have fun!

Step 1

Setup Server on CHIP or Raspberry PI in HOME directory or your choice:

git clone  https://bobburns@gitlab.com/bobburns/fam-server-bin.git

Create server key and add users. How-to.

Step 2

Setup Clients on pocketCHIP:

git clone https://bobburns@gitlab.com/bobburns/fam-client-bin.git

Create keys and RSA key pair. How-to.

Step 3

Exchange keys. Server needs a copy of clients public key. Client needs a copy of server public key. Do this with USB or SCP.

Step 4

Start up server listening on port 16538:

./server &

Connect to Server from pocketChip:

./clientView <ip of server>:16538
username:
password:blabla

Key commands found here

Update

In fam-client-bin or fam-server-bin path:

git pull origin master

Code repositories:

https://gitlab.com/bobburns/fam

Packages if you want to build from source:

https://gitlab.com/bobburns/famsess

https://gitlab.com/bobburns/famdisp

https://gitlab.com/bobburns/message

You will also need tncardoso/gocurses that requires ncurses libraries:

take 1

server.go

package main

import (
	"bytes"
	"fmt"
	"gitlab.com/bobburns/famsess"
	"log"
	"net"
	"os"
)

func main() {
	service := ":16538"
	tcpAddr, err := net.ResolveTCPAddr("tcp4", service)
	checkError(err)

	listener, err := net.ListenTCP("tcp", tcpAddr)
	checkError(err)

	for {
		conn, err := listener.Accept()
		if err != nil {
			continue
		}
		defer conn.Close()
		fmt.Println("listening on port ", service)
		go handleClient(conn)
	}
}
func handleClient(conn net.Conn) {
	s := session.NewSession(conn)

	for {
		log.Println("main loop")
		err := s.ParseIncoming()
		if err != nil {
			log.Printf("Error ParseIncoming [%s]\n", err)
			break
		}

		switch {
		  
		case bytes.Equal(s.RecOp[0:4], session.SendMPre[0:4]):
			log.Println("got SENDMPRE")
			err = s.MessagePreRecv()
		case bytes.Equal(s.RecOp[0:4], session.SendMess[0:4]):
			err = s.MessageRecv()
		case bytes.Equal(s.RecOp[0:4], session.RetrMess[0:4]):
			err = s.MessageRetr()
		case bytes.Equal(s.RecOp[0:4], session.ClientAuth[0:4]):
			err = s.ServerAuth()
		case bytes.Equal(s.RecOp[0:4], session.MessInit[0:4]):
			err = s.MessageInit()
		case bytes.Equal(s.RecOp[0:4], session.ReqMeta[0:4]):
			err = s.ServMeta()
		case bytes.Equal(s.RecOp[0:4], session.DelMess[0:4]):
			err = s.MessageServDel()
		case bytes.Equal(s.RecOp[0:4], session.CChPass[0:4]):
			err = s.ServerChgPass()

		}
		if err != nil {
			// how to handle errors?
			log.Println(err)
		}
		fmt.Println(s.RecOp[0:4])
	}
}

func checkError(err error) {
	if err != nil {
		fmt.Printf("Error: %s\n", err)
		os.Exit(1)
	}
}

Credits

Bob Burns

1 project • 4 followers

Started programming again after 25? years.

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