Claude 24f816b6a3
Consolidate 22 sibling repos into layered organism structure
Place useful parts of the surrounding repos into sica-fondt by layer, per the
body model (Ada = membrane; brain/endocrine/capabilities/knowledge non-Ada):

- brain/        LLM reasoning + providers (dapr, hermes, MoMoA)
- capabilities/ REPRAG sidecars: hermes tools/skills, dapr tools, parallel
                dispatch, A51 channels, and the OSINT cluster
- knowledge/    LORAG corpus: 754 cyber-skills, agency personas, secure-coding,
                MITRE ATT&CK data
- reference/    defensive threat-reference (C3, shhbruh doc) + AdaYaml parser

License handling: AGPL sources (worldosint, advanced_evolution, mercury,
Reticulum) and GPL DeTTECT are SPEC-only clean-room/port descriptions — no
copyleft code copied. MIT/Apache/data parts copied as working trees.

Safety: shhbruh escape/persistence material and C3 covert-C2 kept as reference
only, not wired into the running organism. See CONSOLIDATION.md.

https://claude.ai/code/session_01UehUqEXXJJCsHoA4voCU5c
2026-06-10 06:53:01 +00:00

83 lines
3.1 KiB
Markdown

---
name: implementing-end-to-end-encryption-for-messaging
description: 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
domain: cybersecurity
subdomain: cryptography
tags:
- cryptography
- encryption
- e2e
- messaging
- signal-protocol
version: '1.0'
author: mahipal
license: Apache-2.0
nist_csf:
- PR.DS-01
- PR.DS-02
- PR.DS-10
---
# 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 forward secrecy (compromise of current key does not reveal past messages)
- Handle out-of-order message delivery
- Implement key agreement using X3DH (Extended Triple Diffie-Hellman)
## Key Concepts
### Signal Protocol Components
| Component | Purpose | Algorithm |
|-----------|---------|-----------|
| X3DH | Initial key agreement | X25519 |
| Double Ratchet | Ongoing key management | X25519 + HKDF + AES-GCM |
| Sending Chain | Per-message encryption keys | HMAC-SHA256 chain |
| Receiving Chain | Per-message decryption keys | HMAC-SHA256 chain |
| Root Chain | Derives new chain keys on DH ratchet | HKDF |
### Forward Secrecy
Each message uses a unique encryption key derived from a ratcheting chain. After a key is used, it is deleted, ensuring that compromise of the current state does not reveal previously sent/received messages.
## Security Considerations
- Delete message keys immediately after decryption
- Implement message ordering and replay protection
- Use authenticated encryption (AES-GCM) for all messages
- Protect identity keys with device-level security
- Verify identity keys out-of-band (safety numbers)
## Validation Criteria
- [ ] X25519 key exchange produces shared secret
- [ ] Messages encrypt and decrypt correctly between two parties
- [ ] Different messages produce different ciphertexts
- [ ] Forward secrecy: old keys cannot decrypt new messages
- [ ] Out-of-order messages can be decrypted
- [ ] Tampered messages are rejected by authentication