Beechat Network for Android

Android version of the open source, encrypted, peer-to-peer, Beechat app.

Introduction

Beechat is an open source system which allows people to securely communicate over encrypted peer-to-peer, mesh, radio connections, and without relying on commercial infrastructure.

• No SIM cards, no Internet required.
• No shady tracking.
• We all fully own the system, this way, no one can destroy it.

If you want to send a message to someone outside your range, people in between you two can act as a bridge, without ever knowing the contents of the encrypted message.

Download Android APK

Code

• Java:

  1. MainActivity.java contains code for displaying and interacting with the main application window. At startup, it scans and displays a list of devices available for communication. You can also refresh the list of available devices using the "Refresh" button.
  2. ChatActivity.java contains code for connecting to an available device from the main window and organizing a text chat. The screen contains information about the connection and the ability to return to the main application window. The corresponding XML files are responsible for the design and structure of the activity elements: activity_main.xml and activity_chat.xml.

• client_message_box.xml and server_message_box.xml files are responsible for displaying message boxes between the sending and receiving parties.

• The digi_icon.png file is the application icon.

• The strings.xml file is designed to save strings of constant strings displayed in the application.

• The styles.xml file is for setting colors inside the application.

• The AndroidManifest.xml file is intended for grouping files into one structure and the ability to add permissions within the application.

• The app/build.gradle and project/build.gradle files are intended for building libraries and applications, respectively.

• The settings.gradle, local.properties and gradle.properties files contain different settings for gradle and project.

• The application consists of the following directories:

• BeechatNetwork. Main project directory.
  • BeechatNetwork/app. Main app directory.
    • BeechatNetwork/app/src/main/java. Source code directory.
    • BeechatNetwork/app/main/java/res. Styles code directory.
  • BeechatNetwork/xbee_android_library. Directory contains code of Xbee Library for Android.
  • BeechatNetwork/gradle. Gradle settings directory.

Timeline

• Alpha: basic demo radio chat app without encryption.
• Beta: adding secure encryption & signature layer to the app - production ready.
• Launch: Authenticated, unbannable broadcasts, multiple identities per user, and secure file sending implemented.

Threat model

• MITM Attacks: we assume an intermediary node could spoof the 64 bit hardware address (HWAddr) of both Alice’s and Bob’s radios. The bad actor can then conduct a man in the middle attack. Solution: Alice uses her hash of the Dilithium public key as her address. Any subsequent Kyber encryption keys must be signed by that Dilithium key, even if the bad actor spoofs the HWAddr, they will not be able to see contents of the message as they do not have the private key to decrypt the message.

• DoS attack: an attacker can spam the network and flood it with packets by modifying the open source app and creating an infinite loop sending packets. Attack limits: the bad actor’s packets will only reach 20 hops or less in case the network has fewer nodes. Solution: unknown. One possibility would be automatic agreement on channel switching based on high congestion.

• Harvest and decrypt attack: encrypted messages exchanged between Alice and Bob could be harvested and decrypted with a sufficiently powerful quantum computer through Shor’s Algorithm. Solution: by implementing post-quantum cryptography, not even a quantum computer can decrypt the messages as a discrete logarithm attack is not possible.

Features

Alpha Features

Feature	Description
Basic radio chat	(Complete) Select from nodes in your network and start a chat

Beta Features Q3 2021

Category	Feature	Description
UX	Notifications	(Complete) add system notifications for messages received when the device is locked or in another app.
Security	Extended error catching and debug log system	(Complete) add better error catching to prevent unexpected hang-ups.
Optimisations	Separate thread for listnodes	(Complete) run listnodes method on a separate thread to prevent app hang-up.
UX	Splash screen	(Complete) add a splash screen on startup with progress bar.
Misc.	SQLite DB	(Complete) add database file to be able to save conversations with and other data persistently.
UX	Saved conversations window	(Complete) add a new window containing saved conversations & broadcasts.
UX	Settings window	(Complete) baud rate slider, language, dark mode, wipe database.
UX	Refresh animation	(Complete) show a loading animation when clicking on the refresh button.
Misc.	Receipts	(Complete) Sent & read receipts as well as timestamped messages.
Security	kyber-JNI implementation	(Complete) implementing asymmetric encryption of messages utilising our kyber-JNI repo.
Security	dilithium-JNI implementation	(Complete) implementing digital signature scheme authenticated messages utilising our dilithium-JNI repo.

Public launch (Q1 2022)

Category	Feature	Description
Security	Multiple identities	(Complete) switch between different kyber-dilithium keypairs within the application.
Misc.	Signed broadcasts with dilithium-JNI	allow subscriber nodes to subscribe to publisher nodes. Publisher nodes can then send signed public messages to their subscribers.
Misc.	File sending	(Complete) allow sending of images, docx, pdf and other files in an encrypted manner.

License Information

The hardware is released under the GNU General Public License, version 3.

Distributed as-is; no warranty is given.