Case Study: ECHO

Building the World's First Post-Quantum Secure Messenger

The Problem

The messaging landscape is more fragile than it appears, with critical gaps most users haven’t fully recognized yet. Telegram still doesn’t enable end-to-end encryption by default. WhatsApp continues to collect and share metadata within the Meta ecosystem. Signal, while strong on privacy, falls short on usability features like cloud sync, large-scale group support, and broader platform flexibility. More importantly, none of these platforms are truly prepared for what many cryptographers warn is coming within the next decade: quantum computers capable of breaking today’s encryption standards.

This isn’t a distant or hypothetical risk. Nation-state actors are already carrying out strategies capturing encrypted communications today and storing them until quantum capabilities make decryption feasible. That means conversations assumed to be private now could be exposed years down the line, turning current security gaps into future liabilities.

The shift to post-quantum security is already underway. NIST finalized its post-quantum cryptography standards in August 2024, signaling a clear direction for the industry. Google has set a 2029 target to transition its systems, and companies like IBM are actively working with secure messaging platforms such as Signal and Threema to develop quantum-resistant protocols. The window to build a truly quantum-safe messaging system from the ground up rather than retrofitting legacy infrastructure is rapidly narrowing.

The Approach

Xymera didn’t retrofit security onto an existing system, Echo was built from the ground up on a single premise: adversaries have unlimited time and future technology. Every architectural choice follows from that.

Its encryption uses a hybrid approach (PQXDH), combining X25519 with post-quantum ML-KEM-768. Compromising it would require breaking both layers, which remains infeasible even in a quantum setting. This isn’t optional or experimental, it’s the default and only mode of operation.

The server functions purely as a zero-knowledge relay: it holds encrypted data it can’t read, uses sealed sender mechanisms to conceal who sent messages, and stores files it cannot decrypt. By design, it never has access to message content—even under legal pressure.

Identity is completely independent of phone numbers. Users authenticate with cryptographic key pairs, verified through QR-based fingerprint checks and a transparent, append-only key log rather than telecom systems.

When the internet is unavailable or compromised, Echo can fall back to Bluetooth Low Energy mesh networking. Messages hop between nearby devices without servers, supporting communication during outages, protests, disasters, and on-the-ground operations.

The Result

Echo stands apart as the only messaging platform that brings together a full stack of advanced security and scalability features in one place. It delivers hybrid post-quantum encryption by default, paired with a zero-knowledge server design and sealed sender protections that minimize metadata exposure.

On top of that, it removes reliance on phone numbers entirely, supports encrypted cloud sync, enables massive groups of up to 500,000 members, allows file transfers up to 5GB, and includes BLE-based offline mesh networking for use when the internet is unavailable. The platform also integrates a sandboxed bot ecosystem, cryptographically enforced disappearing messages, and a publicly verifiable key transparency log all while remaining fully open source.

No existing platform matches this breadth. Telegram still lacks default end-to-end encryption and any post-quantum capabilities. Signal has begun adopting post-quantum elements but doesn’t offer cloud sync, large-scale group support, or offline mesh networking. WhatsApp, meanwhile, lacks post-quantum encryption entirely, does not provide meaningful metadata protection, and remains tied to phone-number-based identity.