Module pqxdh 

PQXDH (Post-Quantum Extended Diffie-Hellman) inbox types and cryptographic helpers

This module implements the PQXDH protocol for asynchronous secure communication, based on Signal’s PQXDH specification. It provides:

• Prekey bundle generation and management
• PQXDH key agreement protocol
• Inbox types for different protocols (RPC, messaging, etc.)

Security

PQXDH provides:

• Post-quantum forward secrecy via ML-KEM (using libcrux-ml-kem)
• Classical security via X25519 ECDH
• Authentication via ML-DSA signatures
• Perfect forward secrecy through one-time prekeys

Re-exports

pub use pqxdh_crypto::*;

Modules

pqxdh_crypto

PQXDH cryptographic operations

Structs

PqxdhInbox

PQXDH inbox for connecting to a user

PqxdhInitialMessage

PQXDH initial message sent to establish secure communication (Phase 2)

PqxdhInitialPayload

Initial payload structure for PQXDH sessions

PqxdhPrekeyBundle

PQXDH prekey bundle containing both classical and post-quantum keys

PqxdhPrivateKeys

Private key material for PQXDH operations

PqxdhSessionMessage

PQXDH session message for ongoing communication (Phase 3)

PqxdhSharedSecret

Result of PQXDH key agreement

Enums

InboxType

Inbox type indicating expected responsiveness and access control

PqxdhError

Errors that can occur during PQXDH operations