Anthropic-Cybersecurity-Skills/skills/implementing-end-to-end-encryption-for-messaging/references/standards.md

Standards and References - End-to-End Encryption for Messaging

Signal Protocol Specifications

The Double Ratchet Algorithm

• URL: https://signal.org/docs/specifications/doubleratchet/
• Description: Core key management algorithm for E2EE messaging

The X3DH Key Agreement Protocol

• URL: https://signal.org/docs/specifications/x3dh/
• Description: Initial key exchange using Extended Triple Diffie-Hellman

The Sesame Algorithm

• URL: https://signal.org/docs/specifications/sesame/
• Description: Multi-device session management

Cryptographic Standards

RFC 7748 - Elliptic Curves for Security (X25519)

• URL: https://www.rfc-editor.org/rfc/rfc7748
• Description: X25519 Diffie-Hellman key exchange

RFC 5869 - HKDF (HMAC-based Key Derivation Function)

• URL: https://www.rfc-editor.org/rfc/rfc5869
• Description: Key derivation for chain key updates

RFC 8032 - Edwards-Curve Digital Signature Algorithm (Ed25519)

• URL: https://www.rfc-editor.org/rfc/rfc8032
• Description: Identity key signatures

NIST SP 800-38D - AES-GCM

• URL: https://csrc.nist.gov/publications/detail/sp/800-38d/final
• Description: Authenticated encryption for messages

Python Libraries

cryptography

• X25519: cryptography.hazmat.primitives.asymmetric.x25519
• HKDF: cryptography.hazmat.primitives.kdf.hkdf
• AES-GCM: cryptography.hazmat.primitives.ciphers.aead.AESGCM