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// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// Copyright by contributors to this project.
// SPDX-License-Identifier: (Apache-2.0 OR MIT)
use mls_rs::{
client_builder::MlsConfig,
error::MlsError,
external_client::{
builder::MlsConfig as ExternalMlsConfig, ExternalClient, ExternalReceivedMessage,
ExternalSnapshot,
},
group::{CachedProposal, ReceivedMessage},
identity::{
basic::{BasicCredential, BasicIdentityProvider},
SigningIdentity,
},
CipherSuite, CipherSuiteProvider, Client, CryptoProvider, ExtensionList, MlsMessage,
};
use mls_rs_core::crypto::SignatureSecretKey;
const CIPHERSUITE: CipherSuite = CipherSuite::CURVE25519_AES128;
fn cipher_suite_provider() -> impl CipherSuiteProvider {
crypto_provider()
.cipher_suite_provider(CIPHERSUITE)
.unwrap()
}
fn crypto_provider() -> impl CryptoProvider + Clone {
mls_rs_crypto_openssl::OpensslCryptoProvider::default()
}
#[derive(Default)]
struct BasicServer {
group_state: Vec<u8>,
cached_proposals: Vec<Vec<u8>>,
message_queue: Vec<Vec<u8>>,
}
impl BasicServer {
// Client uploads group data after creating the group
fn create_group(group_info: &[u8]) -> Result<Self, MlsError> {
let server = make_server();
let group_info = MlsMessage::from_bytes(group_info)?;
let group = server.observe_group(group_info, None)?;
Ok(Self {
group_state: group.snapshot().to_bytes()?,
..Default::default()
})
}
// Client uploads a proposal. This doesn't change the server's group state, so clients can
// upload prposals without synchronization (`cached_proposals` and `message_queue` collect
// all proposals in any order).
fn upload_proposal(&mut self, proposal: Vec<u8>) -> Result<(), MlsError> {
let server = make_server();
let group_state = ExternalSnapshot::from_bytes(&self.group_state)?;
let mut group = server.load_group(group_state)?;
let proposal_msg = MlsMessage::from_bytes(&proposal)?;
let res = group.process_incoming_message(proposal_msg)?;
let ExternalReceivedMessage::Proposal(proposal_desc) = res else {
panic!("expected proposal message!")
};
self.cached_proposals
.push(proposal_desc.cached_proposal().to_bytes()?);
self.message_queue.push(proposal);
Ok(())
}
// Client uploads a commit. This changes the server's group state, so in a real application,
// it must be synchronized. That is, only one `upload_commit` operation can succeed.
fn upload_commit(&mut self, commit: Vec<u8>) -> Result<(), MlsError> {
let server = make_server();
let group_state = ExternalSnapshot::from_bytes(&self.group_state)?;
let mut group = server.load_group(group_state)?;
for p in &self.cached_proposals {
group.insert_proposal(CachedProposal::from_bytes(p)?);
}
let commit_msg = MlsMessage::from_bytes(&commit)?;
let res = group.process_incoming_message(commit_msg)?;
let ExternalReceivedMessage::Commit(_commit_desc) = res else {
panic!("expected commit message!")
};
self.cached_proposals = Vec::new();
self.group_state = group.snapshot().to_bytes()?;
self.message_queue.push(commit);
Ok(())
}
pub fn download_messages(&self, i: usize) -> &[Vec<u8>] {
&self.message_queue[i..]
}
}
fn make_server() -> ExternalClient<impl ExternalMlsConfig> {
ExternalClient::builder()
.identity_provider(BasicIdentityProvider)
.crypto_provider(crypto_provider())
.build()
}
fn make_client(name: &str) -> Result<Client<impl MlsConfig>, MlsError> {
let (secret, signing_identity) = make_identity(name);
Ok(Client::builder()
.identity_provider(BasicIdentityProvider)
.crypto_provider(crypto_provider())
.signing_identity(signing_identity, secret, CIPHERSUITE)
.build())
}
fn make_identity(name: &str) -> (SignatureSecretKey, SigningIdentity) {
let cipher_suite = cipher_suite_provider();
let (secret, public) = cipher_suite.signature_key_generate().unwrap();
// Create a basic credential for the session.
// NOTE: BasicCredential is for demonstration purposes and not recommended for production.
// X.509 credentials are recommended.
let basic_identity = BasicCredential::new(name.as_bytes().to_vec());
let identity = SigningIdentity::new(basic_identity.into_credential(), public);
(secret, identity)
}
fn main() -> Result<(), MlsError> {
// Create clients for Alice and Bob
let alice = make_client("alice")?;
let bob = make_client("bob")?;
// Alice creates a group with bob
let mut alice_group = alice.create_group(ExtensionList::default())?;
let bob_key_package = bob.generate_key_package_message()?;
let welcome = &alice_group
.commit_builder()
.add_member(bob_key_package)?
.build()?
.welcome_messages[0];
let (mut bob_group, _) = bob.join_group(None, welcome)?;
alice_group.apply_pending_commit()?;
// Server starts observing Alice's group
let group_info = alice_group.group_info_message(true)?.to_bytes()?;
let mut server = BasicServer::create_group(&group_info)?;
// Bob uploads a proposal
let proposal = bob_group
.propose_group_context_extensions(ExtensionList::new(), Vec::new())?
.to_bytes()?;
server.upload_proposal(proposal)?;
// Alice downloads all messages and commits
for m in server.download_messages(0) {
alice_group.process_incoming_message(MlsMessage::from_bytes(m)?)?;
}
let commit = alice_group
.commit(b"changing extensions".to_vec())?
.commit_message
.to_bytes()?;
server.upload_commit(commit)?;
// Alice waits for an ACK from the server and applies the commit
alice_group.apply_pending_commit()?;
// Bob downloads the commit
let message = server.download_messages(1).first().unwrap();
let res = bob_group.process_incoming_message(MlsMessage::from_bytes(message)?)?;
let ReceivedMessage::Commit(commit_desc) = res else {
panic!("expected commit message")
};
assert_eq!(&commit_desc.authenticated_data, b"changing extensions");
Ok(())
}