Implementing End-to-End Encryption for Messaging

Overview

End-to-end encryption (E2EE) ensures that only the communicating parties can read messages, with no intermediary (including the server) able to decrypt them. This skill implements a simplified version of the Signal Protocol's Double Ratchet algorithm, using X25519 for key exchange, HKDF for key derivation, and AES-256-GCM for message encryption.

When to Use

• When deploying or configuring implementing end to end encryption for messaging capabilities in your environment
• When establishing security controls aligned to compliance requirements
• When building or improving security architecture for this domain
• When conducting security assessments that require this implementation

Prerequisites

• Familiarity with cryptography concepts and tools
• Access to a test or lab environment for safe execution
• Python 3.8+ with required dependencies installed
• Appropriate authorization for any testing activities

Objectives

• Implement X25519 Diffie-Hellman key exchange for session establishment
• Build the Double Ratchet key management algorithm
• Encrypt and decrypt messages with per-message keys
• Implement forw…