Crate offline_protocol_mls 

MLS (Message Layer Security) integration for the Offline Protocol SDK.

This crate provides end-to-end encryption using the MLS protocol via OpenMLS. It supports both 1:1 encrypted messaging and group messaging with forward secrecy and post-compromise security.

Architecture

The crate is designed with a storage-agnostic approach:

• Apps implement the MlsStorage trait for platform-native secure storage
• The MlsManager handles all MLS operations (key generation, encryption, decryption)
• Groups are used for both 1:1 sessions (2-person groups) and multi-party chats

Example

use offline_protocol_mls::{MlsManager, MlsStorage};

// Implement MlsStorage for your platform (iOS Keychain, Android Keystore, etc.)
let storage = MyPlatformStorage::new();

// Create the MLS manager
let manager = MlsManager::new("user123", Box::new(storage))?;

// Generate a key package to share with others
let key_package = manager.generate_key_package()?;

// Create a 1:1 session and send an encrypted message
let ciphertext = manager.encrypt_for_user("bob", b"Hello, Bob!")?;

Re-exports

pub use error::LeafSource;

pub use error::MlsError;

pub use error::Result;

pub use manager::is_mls_framed;

pub use manager::MlsManager;

pub use manager::PushKeyPackage;

pub use manager::MAX_PUSH_KEY_PACKAGES;

pub use storage::MlsStorage;

pub use storage::StorageError;

pub use types::EncryptedMessage;

pub use types::GroupId;

pub use types::GroupInfo;

pub use types::GroupMetadata;

pub use types::GroupRole;

pub use types::KeyPackageBundle;

pub use types::MlsMessageType;

pub use types::ParseGroupRoleError;

pub use types::WelcomeMessage;

Modules

discovery

DiscoveryRecordV1: a signed, non-authoritative claim that a username points at an address.

error

Error types for MLS operations.

group

MLS group management.

invite

The invite payload: a self-verifying {address, pubkey, petname?, sig?} blob for QR codes and links.

manager

Main MLS manager - the primary interface for MLS operations.

provider

Custom OpenMLS provider implementation.

session

1:1 session management using MLS groups.

storage

Storage trait definitions for MLS key material.

types

Types for MLS operations.