Files
T
mukul975 efca3ec611 feat: add NIST CSF 2.0 nist_csf field to all 754 cybersecurity skills
Mapped every skill to NIST CSF 2.0 subcategory IDs (GV/ID/PR/DE/RS/RC functions)
based on subdomain and content analysis. Restores 11 skills corrupted during
prior rebase, re-enriching with ATLAS, D3FEND, NIST AI RMF, and CSF 2.0 fields.

All 754 skills now carry structured mappings for all 5 security frameworks:
- MITRE ATT&CK (in tags)
- MITRE ATLAS v5.5 (atlas_techniques)
- MITRE D3FEND v1.3 (d3fend_techniques)
- NIST AI RMF 1.0 (nist_ai_rmf)
- NIST CSF 2.0 (nist_csf)
2026-04-06 11:17:40 +02:00

3.1 KiB

name, description, domain, subdomain, tags, version, author, license, nist_csf
name description domain subdomain tags version author license nist_csf
implementing-end-to-end-encryption-for-messaging 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 cybersecurity cryptography
cryptography
encryption
e2e
messaging
signal-protocol
1.0 mahipal Apache-2.0
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