Traits & External Types

OpenMLS defines several traits that have to be implemented to use OpenMLS. The main goal is to allow OpenMLS to use different implementations for its cryptographic primitives, persistence, and random number generation. This should make it possible to plug in anything from WebCrypto to secure enclaves.

• Traits
• External Types

Using storage

The store is probably one of the most interesting traits because applications that use OpenMLS will interact with it. See the StorageProvider trait description for details.

In the following examples, we have a ciphersuite and a provider (OpenMlsProvider).

    // First we generate a credential and key package for our user.
    let credential = BasicCredential::new(b"User ID".to_vec());
    let signature_keys = SignatureKeyPair::new(ciphersuite.into()).unwrap();

    // This key package includes the private init and encryption key as well.
    // See [`KeyPackageBundle`].
    let key_package = KeyPackage::builder()
        .build(
            ciphersuite,
            provider,
            &signature_keys,
            CredentialWithKey {
                credential: credential.into(),
                signature_key: signature_keys.to_public_vec().into(),
            },
        )
        .unwrap();

Retrieving a value from the store is as simple as calling read. The retrieved key package bundles the private keys for the init and encryption keys as well.

    // Read the key package
    let read_key_package: Option<KeyPackageBundle> = provider
        .storage()
        .key_package(&hash_ref)
        .expect("Error reading key package");
    assert_eq!(
        read_key_package.unwrap().key_package(),
        key_package.key_package()
    );

The delete is called with the identifier to delete a value.

    // Delete the key package
    let hash_ref = key_package
        .key_package()
        .hash_ref(provider.crypto())
        .unwrap();
    provider
        .storage()
        .delete_key_package(&hash_ref)
        .expect("Error deleting key package");