Awesome Secure Messaging

A curated collection of links for secure messaging. Part of the "Awesome X" series.

The list is periodically updated with new links. Click "Watch" in the right top corner to follow.

Your contributions are welcomed.

Table of Contents

• Fundamentals
• Messaging
• Anonymity
• Censorship Resistance
• Coercion Resistance
• Attacks
• Applications

Fundamentals

• SoK: Secure Messaging - evaluation of current secure messaging solutions based on security, usability and adoption

• Viewing Privacy as a Security Property - presentation by George Danezis that tells the story of privacy as security, informational self-determination

Messaging

• Double Ratchet - two-party protocol to exchange encrypted messages based on shared key

• Bramble Transport Protocol - transport layer security protocol for delay-tolerant networks, provides secure channel between two endpoints

• Bramble Synchronisation Protocol - data synchronisation protocol for delay-tolerant networks

• TreeKEM - Asynchronous Decentralized Key Management for Large Dynamic Groups - efficient way of establishing shared key for large groups with asynchronous group modification perations; proposal for Messaging Layer Security protocol (MLS); similar to Asynchronous Ratcheting Trees (ART) and an evolution thereof

• On Ends-to-Ends Encryption - Asynchronous Group Messaging with Strong Security Guarantees using Asynchronous Ratcheting Trees

• Messaging Layer Security Architecture - IETF draft of security layer for group messaging applications with a large number of participants

Trust establishment

• X3DH - two-party asynchronous key agreement protocol

• Bramble QR Code Protocol - in-person key agreement protocol to establish a shared secret

Session management

• Sesame - session management for async and-multi device setting

Anonymity

• The Differences Between Onion Routing and Mix Networks - brief comparison

• Anonymity Trilemma: Strong Anonymity, Low Bandwidth Overhead, Low Latency—Choose Two - on fundamental tradeoff for anonymous communication protocols

• Selected Papers in Anonymity - meta-list of selected papers in anonymity since 1977

• Sphinx: A Compact and Provably Secure Mix Format - paper on secure and compact message format for mix networks

• Sphinx Mix Network Cryptographic Packet Format Specification - specification for Sphinx mix network packet format

• Introducing Anonymous Communications slides - notes by George Danezis on properties, threat models, systems & attacks

• Anonymous Communications slides at CCC - another overview of anonymous communication systems by George Danezis

• What is a Remailer? - anonyomus remailers tutorial building up from basics

• Cwtch: Privacy Preserving Infrastructure for Asynchronous,Decentralized, Multi-Party and Metadata Resistant Applications - extension of the Ricochet protocol that provides asynchronous, offline and multi-party metadata resistant messaging

Censorship Resistance

• Pluggable Transport - specification initiative to allow applications being used as transports to make network traffic harder to distinguish and block, origins in Tor

• So you want to write a Tor pluggable transport (video) - lightning talk about how to write a pluggable transport for Tor

• Selected Research Papers in Internet Censorship - meta-list of papers on censorship and resistance thereof

Cocercion Resistance

• Coercion-Resistance and Receipt-Freeness in Electronic Voting - academic paper that outlines ways to provide coercion-resistance for electronic voting

• Coercion-Resistant Electronic Elections - paper on coercion resistance and trusted setup requirement

• On-Chain Vote Buying and the Rise of Dark DAOs - on problems of user generated keys and electronic voting

Attacks

• The Sybil Attack - attack on p2p systems from cheap identity generation, requiring some form of logically centralized authority

• Tagging Attacks - adversary recognizing traffic by modfiying it in acceptable fashion

Applications

• Briar - messaging app employing several censorship-resitance techniques, like direct device-to-device comms (bluetooth, wifi), Tor routing

• Signal - widely used security-based messaging app with intermediate server and phone based registration, includes voice calls