Courier279

A secure end-to-end encrypted messaging and sharing app with an immersive 3-D UI

https://www.c279.ml

Team:

• Alexander Tam
  • Frontend
  • 3D Environment
• Tony Wu
  • Backend/DB
  • E2E Crypto
  • DevOps

What is Courier279?

A secure and trustless messaging and sharing application that respects the privacy of its users.

• End-to-end encryption for direct messages, group messages, and files
• Seamless crypto code handles everything from encryption to key management, no special user actions required
• Files utilize seperated volume/header encryption, allowing rapid sharing with any number of users
• Trustless security model ensures the server never has access to users' private data
• Create and manage contacts, and configure sharing permissions among contacts

Courier279 offers a unique 3-D user experience:

• Centers on an immersive first-person 3-D operating environment
• Interactions such as viewing messages, contacts, group messages, etc. will be done in this 3-D environment
• Simple, minimalistic design enables users to focus on the environment created by their conversations.

Features

• 3D environment used for secure messaging between users

• Contact list to manage communications with other users

• Secure file sharing with flexible permissions, encryption transparent to the user

• Manage encrypted group chats and sharing

• Smart updating of contact messages

• Quickly cycle through contacts and group sessions using keybinds alone - no standard button elements used

Technologies

• Frontend use of the TweetNaCL crypto library for end-to-end encryption

  • NaCL box format (ECDH) for direct messages
  • NaCL secretbox format (shared secret key) for group messages and files, key distribution via NaCL box

• Trustless end-to-end encryption and key management

  • Each user has a client-generated EC keypair, created upon signup
    • Private key is encrypted with Scrypt digest of user password, before leaving the client
    • Independent hash of password sent for server authenication, preseving secrecy of the Scrypt digest
    • Private key is restored in the client upon subsequent logins
  • Group message sessions use unique client-generated symmetric keys
    • Symmetric keys re-encrypted with group members' public keys for secure distribution
  • Files use client-side seperate-header encryption for flexible sharing
    • Only symmetric key needs to be re-encrypted for sharing, eliminating unnecessary downloads

• Frontend use of React to manage client state, server communication, and the main 3-D UI

• The UI centers around a 3-D three.js canvas to provide an unique user experience

• Backend composed of an Express server with a MySQL database for data storage

  • Caching via Memcached
  • Uses Long Polling for seamless updates between users

• Automated deployment via Docker, static files served by Nginx with reverse-proxy to Express servers