Model

---

Architecture Overview

SecureComm follows a client-centric security architecture.

Components

• Client Applications
  Responsible for key generation, encryption, and decryption.

• Relay Server
  Facilitates message delivery without access to plaintext or cryptographic keys.

Trust Boundaries

The relay server is treated as an untrusted intermediary.

All cryptographic trust exists exclusively between clients.

Security Model

SecureComm enforces security at the application layer.

Key Principles

• End-to-end encryption by default
• No server-side access to plaintext
• No server-side key storage
• Minimal metadata handling

Security is enforced by design rather than operational policy.

Threat Model

SecureComm considers the following adversaries:

• Network-level attackers
• Malicious or compromised relay servers
• Passive traffic observers
• Unauthorized clients

Out of Scope

• Compromised client devices
• User behavior risks
• Physical access attacks

Cryptographic Design

SecureComm uses established cryptographic primitives and libraries.

Design Principles

• No custom cryptography
• Ephemeral key material where feasible
• Client-side encryption and decryption
• Secure randomness sources

Cryptographic implementation details may evolve over time and are documented accordingly.

Limitations and Assumptions

Assumptions

• Client devices are trusted
• Browsers correctly implement cryptographic APIs
• Users safeguard their own environments

Limitations

• No protection against endpoint compromise
• No message recovery
• No anonymity guarantees against traffic analysis

---