Introduction

DeadLetter

DeadLetter is a censorship-resistant, identity-driven dead-drop communication system.

It allows senders to deliver encrypted messages to recipients without knowing where they are, while recipients can safely fetch, decrypt and acknowledge messages using strong cryptography.

No accounts. No metadata. No central trust beyond cryptographic verification.

Core properties

• Zero knowledge backend — servers never see plaintext
• Post-quantum-safe hybrid crypto design (X25519 + Ed25519 + AES-GCM + HKDF)
• Device trust pinning
• ESP32 hardware dead-drop nodes
• CLI inbox with offline decryption
• Fully self-hostable