openmls/group/mls_group/
mod.rs

1//! MLS Group
2//!
3//! This module contains [`MlsGroup`] and its submodules.
4//!
5
6use past_secrets::MessageSecretsStore;
7use proposal_store::ProposalQueue;
8use serde::{Deserialize, Serialize};
9use tls_codec::Serialize as _;
10
11#[cfg(test)]
12use crate::treesync::node::leaf_node::TreePosition;
13
14use super::proposal_store::{ProposalStore, QueuedProposal};
15use crate::{
16    binary_tree::array_representation::LeafNodeIndex,
17    ciphersuite::{hash_ref::ProposalRef, signable::Signable},
18    credentials::Credential,
19    error::LibraryError,
20    extensions::Extensions,
21    framing::{mls_auth_content::AuthenticatedContent, *},
22    group::{
23        CreateGroupContextExtProposalError, DeletePastEpochSecretsError, Extension, ExtensionType,
24        ExternalPubExtension, GroupContext, GroupEpoch, GroupId, MlsGroupJoinConfig,
25        MlsGroupStateError, OutgoingWireFormatPolicy, PublicGroup, RatchetTreeExtension,
26        RequiredCapabilitiesExtension, SetPastEpochDeletionPolicyError, StagedCommit,
27    },
28    key_packages::KeyPackageBundle,
29    messages::{
30        group_info::{GroupInfo, GroupInfoTBS, VerifiableGroupInfo},
31        proposals::*,
32        ConfirmationTag, GroupSecrets, Welcome,
33    },
34    schedule::{
35        message_secrets::MessageSecrets,
36        psk::{load_psks, store::ResumptionPskStore, PskSecret},
37        GroupEpochSecrets, JoinerSecret, KeySchedule,
38    },
39    storage::{OpenMlsProvider, StorageProvider},
40    treesync::{
41        node::{encryption_keys::EncryptionKeyPair, leaf_node::LeafNode},
42        RatchetTree, TreeSync,
43    },
44    versions::ProtocolVersion,
45};
46use openmls_traits::{signatures::Signer, storage::StorageProvider as _, types::Ciphersuite};
47
48#[cfg(feature = "extensions-draft-08")]
49use crate::schedule::{application_export_tree::ApplicationExportTree, ApplicationExportSecret};
50
51// Private
52mod application;
53mod exporting;
54mod updates;
55
56use config::*;
57
58// Crate
59pub(crate) mod builder;
60pub(crate) mod commit_builder;
61pub(crate) mod config;
62pub(crate) mod creation;
63pub(crate) mod errors;
64pub(crate) mod membership;
65pub(crate) mod past_secrets;
66pub(crate) mod processing;
67pub(crate) mod proposal;
68pub(crate) mod proposal_store;
69pub(crate) mod staged_commit;
70
71#[cfg(feature = "extensions-draft-08")]
72pub(crate) mod app_ephemeral;
73
74// Tests
75#[cfg(test)]
76pub(crate) mod tests_and_kats;
77
78#[derive(Debug)]
79pub(crate) struct CreateCommitResult {
80    pub(crate) commit: AuthenticatedContent,
81    pub(crate) welcome_option: Option<Welcome>,
82    pub(crate) staged_commit: StagedCommit,
83    pub(crate) group_info: Option<GroupInfo>,
84}
85
86/// A member in the group is identified by this [`Member`] struct.
87#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
88pub struct Member {
89    /// The member's leaf index in the ratchet tree.
90    pub index: LeafNodeIndex,
91    /// The member's credential.
92    pub credential: Credential,
93    /// The member's public HPHKE encryption key.
94    pub encryption_key: Vec<u8>,
95    /// The member's public signature key.
96    pub signature_key: Vec<u8>,
97}
98
99impl Member {
100    /// Create new member.
101    pub fn new(
102        index: LeafNodeIndex,
103        encryption_key: Vec<u8>,
104        signature_key: Vec<u8>,
105        credential: Credential,
106    ) -> Self {
107        Self {
108            index,
109            encryption_key,
110            signature_key,
111            credential,
112        }
113    }
114}
115
116/// Pending Commit state. Differentiates between Commits issued by group members
117/// and External Commits.
118#[derive(Debug, Serialize, Deserialize)]
119#[cfg_attr(any(test, feature = "test-utils"), derive(Clone, PartialEq))]
120pub enum PendingCommitState {
121    /// Commit from a group member
122    Member(StagedCommit),
123    /// Commit from an external joiner
124    External(StagedCommit),
125}
126
127impl PendingCommitState {
128    /// Returns a reference to the [`StagedCommit`] contained in the
129    /// [`PendingCommitState`] enum.
130    pub(crate) fn staged_commit(&self) -> &StagedCommit {
131        match self {
132            PendingCommitState::Member(pc) => pc,
133            PendingCommitState::External(pc) => pc,
134        }
135    }
136}
137
138impl From<PendingCommitState> for StagedCommit {
139    fn from(pcs: PendingCommitState) -> Self {
140        match pcs {
141            PendingCommitState::Member(pc) => pc,
142            PendingCommitState::External(pc) => pc,
143        }
144    }
145}
146
147/// [`MlsGroupState`] determines the state of an [`MlsGroup`]. The different
148/// states and their transitions are as follows:
149///
150/// * [`MlsGroupState::Operational`]: This is the main state of the group, which
151///   allows access to all of its functionality, (except merging pending commits,
152///   see the [`MlsGroupState::PendingCommit`] for more information) and it's the
153///   state the group starts in (except when created via
154///   [`MlsGroup::external_commit_builder()`], see the functions documentation for
155///   more information). From this `Operational`, the group state can either
156///   transition to [`MlsGroupState::Inactive`], when it processes a commit that
157///   removes this client from the group, or to [`MlsGroupState::PendingCommit`],
158///   when this client creates a commit.
159///
160/// * [`MlsGroupState::Inactive`]: A group can enter this state from any other
161///   state when it processes a commit that removes this client from the group.
162///   This is a terminal state that the group can not exit from. If the clients
163///   wants to re-join the group, it can either be added by a group member or it
164///   can join via external commit.
165///
166/// * [`MlsGroupState::PendingCommit`]: This state is split into two possible
167///   sub-states, one for each Commit type:
168///   [`PendingCommitState::Member`] and [`PendingCommitState::External`]:
169///
170///   * If the client creates a commit for this group, the `PendingCommit` state
171///     is entered with [`PendingCommitState::Member`] and with the [`StagedCommit`] as
172///     additional state variable. In this state, it can perform the same
173///     operations as in the [`MlsGroupState::Operational`], except that it cannot
174///     create proposals or commits. However, it can merge or clear the stored
175///     [`StagedCommit`], where both actions result in a transition to the
176///     [`MlsGroupState::Operational`]. Additionally, if a commit from another
177///     group member is processed, the own pending commit is also cleared and
178///     either the `Inactive` state is entered (if this client was removed from
179///     the group as part of the processed commit), or the `Operational` state is
180///     entered.
181///
182///   * A group can enter the [`PendingCommitState::External`] sub-state only as
183///     the initial state when the group is created via
184///     [`MlsGroup::external_commit_builder()`]. In contrast to the
185///     [`PendingCommitState::Member`] `PendingCommit` state, the only possible
186///     functionality that can be used is the [`MlsGroup::merge_pending_commit()`]
187///     function, which merges the pending external commit and transitions the
188///     state to [`MlsGroupState::PendingCommit`]. For more information on the
189///     external commit process, see [`MlsGroup::external_commit_builder()`] or
190///     Section 11.2.1 of the MLS specification.
191#[derive(Debug, Serialize, Deserialize)]
192#[cfg_attr(any(test, feature = "test-utils"), derive(Clone, PartialEq))]
193pub enum MlsGroupState {
194    /// There is currently a pending Commit that hasn't been merged yet.
195    PendingCommit(Box<PendingCommitState>),
196    /// The group state is in an opertaional state, where new messages and Commits can be created.
197    Operational,
198    /// The group is inactive because the member has been removed.
199    Inactive,
200}
201
202/// A `MlsGroup` represents an MLS group with a high-level API. The API exposes
203/// high level functions to manage a group by adding/removing members, get the
204/// current member list, etc.
205///
206/// The API is modeled such that it can serve as a direct interface to the
207/// Delivery Service. Functions that modify the public state of the group will
208/// return a `Vec<MLSMessageOut>` that can be sent to the Delivery Service
209/// directly. Conversely, incoming messages from the Delivery Service can be fed
210/// into [process_message()](`MlsGroup::process_message()`).
211///
212/// An `MlsGroup` has an internal queue of pending proposals that builds up as
213/// new messages are processed. When creating proposals, those messages are not
214/// automatically appended to this queue, instead they have to be processed
215/// again through [process_message()](`MlsGroup::process_message()`). This
216/// allows the Delivery Service to reject them (e.g. if they reference the wrong
217/// epoch).
218///
219/// If incoming messages or applied operations are semantically or syntactically
220/// incorrect, an error event will be returned with a corresponding error
221/// message and the state of the group will remain unchanged.
222///
223/// An `MlsGroup` has an internal state variable determining if it is active or
224/// inactive, as well as if it has a pending commit. See [`MlsGroupState`] for
225/// more information.
226#[derive(Debug)]
227#[cfg_attr(feature = "test-utils", derive(Clone, PartialEq))]
228pub struct MlsGroup {
229    /// The group configuration. See [`MlsGroupJoinConfig`] for more information.
230    mls_group_config: MlsGroupJoinConfig,
231    /// The public state of the group.
232    public_group: PublicGroup,
233    /// Epoch-specific secrets of the group.
234    group_epoch_secrets: GroupEpochSecrets,
235    /// The own leaf index in the ratchet tree.
236    own_leaf_index: LeafNodeIndex,
237    /// A [`MessageSecretsStore`] that stores message secrets.
238    /// By default this store has the length of 1, i.e. only the [`MessageSecrets`]
239    /// of the current epoch is kept.
240    /// If more secrets from past epochs should be kept in order to be
241    /// able to decrypt application messages from previous epochs, the size of
242    /// the store must be increased through [`max_past_epochs()`].
243    message_secrets_store: MessageSecretsStore,
244    // Resumption psk store. This is where the resumption psks are kept in a rollover list.
245    resumption_psk_store: ResumptionPskStore,
246    // Own [`LeafNode`]s that were created for update proposals and that
247    // are needed in case an update proposal is committed by another group
248    // member. The vector is emptied after every epoch change.
249    own_leaf_nodes: Vec<LeafNode>,
250    // Additional authenticated data (AAD) for the next outgoing message. This
251    // is ephemeral and will be reset by every API call that successfully
252    // returns an [`MlsMessageOut`].
253    aad: Vec<u8>,
254    // A variable that indicates the state of the group. See [`MlsGroupState`]
255    // for more information.
256    group_state: MlsGroupState,
257    /// The state of the Application Exporter. See the MLS Extensions Draft 08
258    /// for more information. This is `None` if an old OpenMLS group state was
259    /// loaded and has not yet merged a commit.
260    #[cfg(feature = "extensions-draft-08")]
261    application_export_tree: Option<ApplicationExportTree>,
262}
263
264impl MlsGroup {
265    // === Configuration ===
266
267    /// Returns the configuration.
268    pub fn configuration(&self) -> &MlsGroupJoinConfig {
269        &self.mls_group_config
270    }
271
272    /// Sets the configuration.
273    pub fn set_configuration<Storage: StorageProvider>(
274        &mut self,
275        storage: &Storage,
276        mls_group_config: &MlsGroupJoinConfig,
277    ) -> Result<(), Storage::Error> {
278        self.mls_group_config = mls_group_config.clone();
279        storage.write_mls_join_config(self.group_id(), mls_group_config)
280    }
281
282    /// Sets the additional authenticated data (AAD) for the next outgoing
283    /// message. This is ephemeral and will be reset by every API call that
284    /// successfully returns an [`MlsMessageOut`].
285    pub fn set_aad(&mut self, aad: Vec<u8>) {
286        self.aad = aad;
287    }
288
289    /// Returns the additional authenticated data (AAD) for the next outgoing
290    /// message.
291    pub fn aad(&self) -> &[u8] {
292        &self.aad
293    }
294
295    // === Advanced functions ===
296
297    /// Returns the group's ciphersuite.
298    pub fn ciphersuite(&self) -> Ciphersuite {
299        self.public_group.ciphersuite()
300    }
301
302    /// Get confirmation tag.
303    pub fn confirmation_tag(&self) -> &ConfirmationTag {
304        self.public_group.confirmation_tag()
305    }
306
307    /// Returns whether the own client is still a member of the group or if it
308    /// was already evicted
309    pub fn is_active(&self) -> bool {
310        !matches!(self.group_state, MlsGroupState::Inactive)
311    }
312
313    /// Returns own credential. If the group is inactive, it returns a
314    /// `UseAfterEviction` error.
315    pub fn credential(&self) -> Result<&Credential, MlsGroupStateError> {
316        if !self.is_active() {
317            return Err(MlsGroupStateError::UseAfterEviction);
318        }
319        self.public_group
320            .leaf(self.own_leaf_index())
321            .map(|node| node.credential())
322            .ok_or_else(|| LibraryError::custom("Own leaf node missing").into())
323    }
324
325    /// Returns the leaf index of the client in the tree owning this group.
326    pub fn own_leaf_index(&self) -> LeafNodeIndex {
327        self.own_leaf_index
328    }
329
330    /// Returns the leaf node of the client in the tree owning this group.
331    pub fn own_leaf_node(&self) -> Option<&LeafNode> {
332        self.public_group().leaf(self.own_leaf_index())
333    }
334
335    /// Returns the group ID.
336    pub fn group_id(&self) -> &GroupId {
337        self.public_group.group_id()
338    }
339
340    /// Returns the epoch.
341    pub fn epoch(&self) -> GroupEpoch {
342        self.public_group.group_context().epoch()
343    }
344
345    /// Returns an `Iterator` over pending proposals.
346    pub fn pending_proposals(&self) -> impl Iterator<Item = &QueuedProposal> {
347        self.proposal_store().proposals()
348    }
349
350    /// Returns the current tree state of the group, in the form of a [`TreeSync`].
351    pub fn treesync(&self) -> &TreeSync {
352        self.public_group.treesync()
353    }
354
355    /// Returns a reference to the [`StagedCommit`] of the most recently created
356    /// commit. If there was no commit created in this epoch, either because
357    /// this commit or another commit was merged, it returns `None`.
358    pub fn pending_commit(&self) -> Option<&StagedCommit> {
359        match self.group_state {
360            MlsGroupState::PendingCommit(ref pending_commit_state) => {
361                Some(pending_commit_state.staged_commit())
362            }
363            MlsGroupState::Operational => None,
364            MlsGroupState::Inactive => None,
365        }
366    }
367
368    /// Sets the `group_state` to [`MlsGroupState::Operational`], thus clearing
369    /// any potentially pending commits.
370    ///
371    /// Note that this has no effect if the group was created through an external commit and
372    /// the resulting external commit has not been merged yet. For more
373    /// information, see [`MlsGroup::external_commit_builder()`].
374    ///
375    /// Use with caution! This function should only be used if it is clear that
376    /// the pending commit will not be used in the group. In particular, if a
377    /// pending commit is later accepted by the group, this client will lack the
378    /// key material to encrypt or decrypt group messages.
379    pub fn clear_pending_commit<Storage: StorageProvider>(
380        &mut self,
381        storage: &Storage,
382    ) -> Result<(), Storage::Error> {
383        match self.group_state {
384            MlsGroupState::PendingCommit(ref pending_commit_state) => {
385                if let PendingCommitState::Member(_) = **pending_commit_state {
386                    self.group_state = MlsGroupState::Operational;
387                    storage.write_group_state(self.group_id(), &self.group_state)
388                } else {
389                    Ok(())
390                }
391            }
392            MlsGroupState::Operational | MlsGroupState::Inactive => Ok(()),
393        }
394    }
395
396    /// Clear the pending proposals, if the proposal store is not empty.
397    ///
398    /// Warning: Once the pending proposals are cleared it will be impossible to process
399    /// a Commit message that references those proposals. Only use this
400    /// function as a last resort, e.g. when a call to
401    /// `MlsGroup::commit_to_pending_proposals` fails.
402    pub fn clear_pending_proposals<Storage: StorageProvider>(
403        &mut self,
404        storage: &Storage,
405    ) -> Result<(), Storage::Error> {
406        // If the proposal store is not empty...
407        if !self.proposal_store().is_empty() {
408            // Empty the proposal store
409            self.proposal_store_mut().empty();
410
411            // Clear proposals in storage
412            storage.clear_proposal_queue::<GroupId, ProposalRef>(self.group_id())?;
413        }
414
415        Ok(())
416    }
417
418    /// Get a reference to the group context [`Extensions`] of this [`MlsGroup`].
419    pub fn extensions(&self) -> &Extensions<GroupContext> {
420        self.public_group().group_context().extensions()
421    }
422
423    /// Returns the index of the sender of a staged, external commit.
424    pub fn ext_commit_sender_index(
425        &self,
426        commit: &StagedCommit,
427    ) -> Result<LeafNodeIndex, LibraryError> {
428        self.public_group().ext_commit_sender_index(commit)
429    }
430
431    // === Storage Methods ===
432
433    /// Loads the state of the group with given id from persisted state.
434    pub fn load<Storage: crate::storage::StorageProvider>(
435        storage: &Storage,
436        group_id: &GroupId,
437    ) -> Result<Option<MlsGroup>, Storage::Error> {
438        let public_group = PublicGroup::load(storage, group_id)?;
439        let group_epoch_secrets = storage.group_epoch_secrets(group_id)?;
440        let own_leaf_index = storage.own_leaf_index(group_id)?;
441        let message_secrets_store = storage.message_secrets(group_id)?;
442        let resumption_psk_store = storage.resumption_psk_store(group_id)?;
443        let mls_group_config = storage.mls_group_join_config(group_id)?;
444        let own_leaf_nodes = storage.own_leaf_nodes(group_id)?;
445        let group_state = storage.group_state(group_id)?;
446        #[cfg(feature = "extensions-draft-08")]
447        let application_export_tree = storage.application_export_tree(group_id)?;
448
449        let build = || -> Option<Self> {
450            Some(Self {
451                public_group: public_group?,
452                group_epoch_secrets: group_epoch_secrets?,
453                own_leaf_index: own_leaf_index?,
454                message_secrets_store: message_secrets_store?,
455                resumption_psk_store: resumption_psk_store?,
456                mls_group_config: mls_group_config?,
457                own_leaf_nodes,
458                aad: vec![],
459                group_state: group_state?,
460                #[cfg(feature = "extensions-draft-08")]
461                application_export_tree,
462            })
463        };
464
465        Ok(build())
466    }
467
468    /// Remove the persisted state of this group from storage. Note that
469    /// signature key material is not managed by OpenMLS and has to be removed
470    /// from the storage provider separately (if desired).
471    pub fn delete<Storage: crate::storage::StorageProvider>(
472        &mut self,
473        storage: &Storage,
474    ) -> Result<(), Storage::Error> {
475        PublicGroup::delete(storage, self.group_id())?;
476        storage.delete_own_leaf_index(self.group_id())?;
477        storage.delete_group_epoch_secrets(self.group_id())?;
478        storage.delete_message_secrets(self.group_id())?;
479        storage.delete_all_resumption_psk_secrets(self.group_id())?;
480        storage.delete_group_config(self.group_id())?;
481        storage.delete_own_leaf_nodes(self.group_id())?;
482        storage.delete_group_state(self.group_id())?;
483        storage.clear_proposal_queue::<GroupId, ProposalRef>(self.group_id())?;
484
485        #[cfg(feature = "extensions-draft-08")]
486        storage.delete_application_export_tree::<_, ApplicationExportTree>(self.group_id())?;
487
488        self.proposal_store_mut().empty();
489        storage.delete_encryption_epoch_key_pairs(
490            self.group_id(),
491            &self.epoch(),
492            self.own_leaf_index().u32(),
493        )?;
494
495        Ok(())
496    }
497
498    // === Extensions ===
499
500    /// Exports the Ratchet Tree.
501    pub fn export_ratchet_tree(&self) -> RatchetTree {
502        self.public_group().export_ratchet_tree()
503    }
504}
505
506// Crate-public functions
507impl MlsGroup {
508    /// Get the required capabilities extension of this group.
509    pub(crate) fn required_capabilities(&self) -> Option<&RequiredCapabilitiesExtension> {
510        self.public_group.required_capabilities()
511    }
512
513    /// Get a reference to the group epoch secrets from the group
514    pub(crate) fn group_epoch_secrets(&self) -> &GroupEpochSecrets {
515        &self.group_epoch_secrets
516    }
517
518    /// Get a reference to the message secrets from a group
519    pub(crate) fn message_secrets(&self) -> &MessageSecrets {
520        self.message_secrets_store.message_secrets()
521    }
522
523    /// Sets the size of the [`MessageSecretsStore`], i.e. the number of past
524    /// epochs to keep.
525    /// This allows application messages from previous epochs to be decrypted.
526    pub(crate) fn resize_message_secrets_store(&mut self, policy: &PastEpochDeletionPolicy) {
527        self.message_secrets_store.resize(policy);
528    }
529
530    /// Get the past epoch secret deletion policy for the group.
531    pub fn past_epoch_deletion_policy(&self) -> &PastEpochDeletionPolicy {
532        self.mls_group_config.past_epoch_deletion_policy()
533    }
534
535    /// Set the past epoch secret deletion policy for the group.
536    pub fn set_past_epoch_deletion_policy<Provider: OpenMlsProvider>(
537        &mut self,
538        provider: &Provider,
539        policy: PastEpochDeletionPolicy,
540    ) -> Result<(), SetPastEpochDeletionPolicyError<Provider::StorageError>> {
541        // resize the store
542        self.resize_message_secrets_store(&policy);
543
544        // set the policy on the join config
545        self.mls_group_config.past_epoch_deletion_policy = policy;
546
547        // persist the join config
548        provider
549            .storage()
550            .write_mls_join_config(self.group_id(), &self.mls_group_config)?;
551
552        // update the message secrets store in storage
553        provider
554            .storage()
555            .write_message_secrets(self.group_id(), &self.message_secrets_store)?;
556
557        Ok(())
558    }
559
560    /// Get the message secrets. Either from the secrets store or from the group.
561    pub(crate) fn message_secrets_for_epoch_mut(
562        &mut self,
563        epoch: GroupEpoch,
564    ) -> Result<&mut MessageSecrets, SecretTreeError> {
565        if epoch < self.context().epoch() {
566            self.message_secrets_store
567                .secrets_for_epoch_mut(epoch)
568                .ok_or(SecretTreeError::TooDistantInThePast)
569        } else {
570            Ok(self.message_secrets_store.message_secrets_mut())
571        }
572    }
573
574    /// Get the message secrets. Either from the secrets store or from the group.
575    pub(crate) fn message_secrets_for_epoch(
576        &self,
577        epoch: GroupEpoch,
578    ) -> Result<&MessageSecrets, SecretTreeError> {
579        if epoch < self.context().epoch() {
580            self.message_secrets_store
581                .secrets_for_epoch(epoch)
582                .ok_or(SecretTreeError::TooDistantInThePast)
583        } else {
584            Ok(self.message_secrets_store.message_secrets())
585        }
586    }
587
588    /// Get the message secrets and leaves for the given epoch. Either from the
589    /// secrets store or from the group.
590    ///
591    /// Note that the leaves vector is empty for message secrets of the current
592    /// epoch. The caller can use treesync in this case.
593    pub(crate) fn message_secrets_and_leaves(
594        &self,
595        epoch: GroupEpoch,
596    ) -> Result<(&MessageSecrets, &[Member]), SecretTreeError> {
597        if epoch < self.context().epoch() {
598            self.message_secrets_store
599                .secrets_and_leaves_for_epoch(epoch)
600                .ok_or(SecretTreeError::TooDistantInThePast)
601        } else {
602            // No need for leaves here. The tree of the current epoch is
603            // available to the caller.
604            Ok((self.message_secrets_store.message_secrets(), &[]))
605        }
606    }
607
608    /// Create a new group context extension proposal
609    pub(crate) fn create_group_context_ext_proposal<Provider: OpenMlsProvider>(
610        &self,
611        framing_parameters: FramingParameters,
612        extensions: Extensions<GroupContext>,
613        signer: &impl Signer,
614    ) -> Result<AuthenticatedContent, CreateGroupContextExtProposalError<Provider::StorageError>>
615    {
616        // Ensure that the group supports all the extensions that are wanted.
617        let required_extension = extensions
618            .iter()
619            .find(|extension| extension.extension_type() == ExtensionType::RequiredCapabilities);
620        if let Some(required_extension) = required_extension {
621            let required_capabilities = required_extension.as_required_capabilities_extension()?;
622            // Ensure we support all the capabilities.
623            self.own_leaf_node()
624                .ok_or_else(|| LibraryError::custom("Tree has no own leaf."))?
625                .capabilities()
626                .supports_required_capabilities(required_capabilities)?;
627
628            // Ensure that all other leaf nodes support all the required
629            // extensions as well.
630            self.public_group()
631                .check_extension_support(required_capabilities.extension_types())?;
632        }
633        let proposal = GroupContextExtensionProposal::new(extensions);
634        let proposal = Proposal::GroupContextExtensions(Box::new(proposal));
635        AuthenticatedContent::member_proposal(
636            framing_parameters,
637            self.own_leaf_index(),
638            proposal,
639            self.context(),
640            signer,
641        )
642        .map_err(|e| e.into())
643    }
644
645    // Encrypt an AuthenticatedContent into an PrivateMessage
646    pub(crate) fn encrypt<Provider: OpenMlsProvider>(
647        &mut self,
648        public_message: AuthenticatedContent,
649        provider: &Provider,
650    ) -> Result<PrivateMessage, MessageEncryptionError<Provider::StorageError>> {
651        let padding_size = self.configuration().padding_size();
652        let msg = PrivateMessage::try_from_authenticated_content(
653            provider.crypto(),
654            provider.rand(),
655            &public_message,
656            self.ciphersuite(),
657            self.message_secrets_store.message_secrets_mut(),
658            padding_size,
659        )?;
660
661        provider
662            .storage()
663            .write_message_secrets(self.group_id(), &self.message_secrets_store)
664            .map_err(MessageEncryptionError::StorageError)?;
665
666        Ok(msg)
667    }
668
669    /// Group framing parameters
670    pub(crate) fn framing_parameters(&self) -> FramingParameters<'_> {
671        FramingParameters::new(
672            &self.aad,
673            self.mls_group_config.wire_format_policy().outgoing(),
674        )
675    }
676
677    /// Delete all past epoch secrets.
678    ///
679    /// For more information on the arguments to this method, see [`PastEpochDeletion`].
680    pub fn delete_past_epoch_secrets<Provider: OpenMlsProvider>(
681        &mut self,
682        provider: &Provider,
683        policy: PastEpochDeletion,
684    ) -> Result<(), DeletePastEpochSecretsError<Provider::StorageError>> {
685        // delete past epoch secrets in memory
686        self.message_secrets_store.delete_past_epoch_secrets(policy);
687        // update the message secrets store in storage
688        provider
689            .storage()
690            .write_message_secrets(self.group_id(), &self.message_secrets_store)?;
691
692        Ok(())
693    }
694
695    /// Returns a reference to the proposal store.
696    pub fn proposal_store(&self) -> &ProposalStore {
697        self.public_group.proposal_store()
698    }
699
700    /// Returns a mutable reference to the proposal store.
701    pub(crate) fn proposal_store_mut(&mut self) -> &mut ProposalStore {
702        self.public_group.proposal_store_mut()
703    }
704
705    /// Get the group context
706    pub(crate) fn context(&self) -> &GroupContext {
707        self.public_group.group_context()
708    }
709
710    /// Get the MLS version used in this group.
711    pub(crate) fn version(&self) -> ProtocolVersion {
712        self.public_group.version()
713    }
714
715    /// Resets the AAD.
716    #[inline]
717    pub(crate) fn reset_aad(&mut self) {
718        self.aad.clear();
719    }
720
721    /// Returns a reference to the public group.
722    pub fn public_group(&self) -> &PublicGroup {
723        &self.public_group
724    }
725}
726
727// Private methods of MlsGroup
728impl MlsGroup {
729    /// Store the given [`EncryptionKeyPair`]s in the `provider`'s key store
730    /// indexed by this group's [`GroupId`] and [`GroupEpoch`].
731    ///
732    /// Returns an error if access to the key store fails.
733    pub(super) fn store_epoch_keypairs<Storage: StorageProvider>(
734        &self,
735        store: &Storage,
736        keypair_references: &[EncryptionKeyPair],
737    ) -> Result<(), Storage::Error> {
738        store.write_encryption_epoch_key_pairs(
739            self.group_id(),
740            &self.context().epoch(),
741            self.own_leaf_index().u32(),
742            keypair_references,
743        )
744    }
745
746    /// Read the [`EncryptionKeyPair`]s of this group and its current
747    /// [`GroupEpoch`] from the `provider`'s storage.
748    ///
749    /// Returns an error if the lookup in the [`StorageProvider`] fails.
750    pub(super) fn read_epoch_keypairs<Storage: StorageProvider>(
751        &self,
752        store: &Storage,
753    ) -> Result<Vec<EncryptionKeyPair>, Storage::Error> {
754        store.encryption_epoch_key_pairs(
755            self.group_id(),
756            &self.context().epoch(),
757            self.own_leaf_index().u32(),
758        )
759    }
760
761    /// Delete the [`EncryptionKeyPair`]s from the previous [`GroupEpoch`] from
762    /// the `provider`'s key store.
763    ///
764    /// Returns an error if access to the key store fails.
765    pub(super) fn delete_previous_epoch_keypairs<Storage: StorageProvider>(
766        &self,
767        store: &Storage,
768    ) -> Result<(), Storage::Error> {
769        store.delete_encryption_epoch_key_pairs(
770            self.group_id(),
771            &GroupEpoch::from(self.context().epoch().as_u64() - 1),
772            self.own_leaf_index().u32(),
773        )
774    }
775
776    /// Stores the state of this group. Only to be called from constructors to
777    /// store the initial state of the group.
778    pub(super) fn store<Storage: crate::storage::StorageProvider>(
779        &self,
780        storage: &Storage,
781    ) -> Result<(), Storage::Error> {
782        self.public_group.store(storage)?;
783        storage.write_group_epoch_secrets(self.group_id(), &self.group_epoch_secrets)?;
784        storage.write_own_leaf_index(self.group_id(), &self.own_leaf_index)?;
785        storage.write_message_secrets(self.group_id(), &self.message_secrets_store)?;
786        storage.write_resumption_psk_store(self.group_id(), &self.resumption_psk_store)?;
787        storage.write_mls_join_config(self.group_id(), &self.mls_group_config)?;
788        storage.write_group_state(self.group_id(), &self.group_state)?;
789        #[cfg(feature = "extensions-draft-08")]
790        if let Some(application_export_tree) = &self.application_export_tree {
791            storage.write_application_export_tree(self.group_id(), application_export_tree)?;
792        }
793
794        Ok(())
795    }
796
797    /// Converts PublicMessage to MlsMessage. Depending on whether handshake
798    /// message should be encrypted, PublicMessage messages are encrypted to
799    /// PrivateMessage first.
800    fn content_to_mls_message(
801        &mut self,
802        mls_auth_content: AuthenticatedContent,
803        provider: &impl OpenMlsProvider,
804    ) -> Result<MlsMessageOut, LibraryError> {
805        let msg = match self.configuration().wire_format_policy().outgoing() {
806            OutgoingWireFormatPolicy::AlwaysPlaintext => {
807                let mut plaintext: PublicMessage = mls_auth_content.into();
808                // Set the membership tag only if the sender type is `Member`.
809                if plaintext.sender().is_member() {
810                    plaintext.set_membership_tag(
811                        provider.crypto(),
812                        self.ciphersuite(),
813                        self.message_secrets().membership_key(),
814                        self.message_secrets().serialized_context(),
815                    )?;
816                }
817                plaintext.into()
818            }
819            OutgoingWireFormatPolicy::AlwaysCiphertext => {
820                let ciphertext = self
821                    .encrypt(mls_auth_content, provider)
822                    // We can be sure the encryption will work because the plaintext was created by us
823                    .map_err(|_| LibraryError::custom("Malformed plaintext"))?;
824                MlsMessageOut::from_private_message(ciphertext, self.version())
825            }
826        };
827        Ok(msg)
828    }
829
830    /// Check if the group is operational. Throws an error if the group is
831    /// inactive or if there is a pending commit.
832    fn is_operational(&self) -> Result<(), MlsGroupStateError> {
833        match self.group_state {
834            MlsGroupState::PendingCommit(_) => Err(MlsGroupStateError::PendingCommit),
835            MlsGroupState::Inactive => Err(MlsGroupStateError::UseAfterEviction),
836            MlsGroupState::Operational => Ok(()),
837        }
838    }
839}
840
841// Methods used in tests
842impl MlsGroup {
843    #[cfg(any(feature = "test-utils", test))]
844    pub fn export_group_context(&self) -> &GroupContext {
845        self.context()
846    }
847
848    #[cfg(any(feature = "test-utils", test))]
849    pub fn tree_hash(&self) -> &[u8] {
850        self.public_group().group_context().tree_hash()
851    }
852
853    #[cfg(any(feature = "test-utils", test))]
854    pub(crate) fn message_secrets_test_mut(&mut self) -> &mut MessageSecrets {
855        self.message_secrets_store.message_secrets_mut()
856    }
857
858    #[cfg(any(feature = "test-utils", test))]
859    pub fn print_ratchet_tree(&self, message: &str) {
860        println!("{}: {}", message, self.public_group().export_ratchet_tree());
861    }
862
863    #[cfg(any(feature = "test-utils", test))]
864    pub(crate) fn context_mut(&mut self) -> &mut GroupContext {
865        self.public_group.context_mut()
866    }
867
868    #[cfg(test)]
869    pub(crate) fn set_own_leaf_index(&mut self, own_leaf_index: LeafNodeIndex) {
870        self.own_leaf_index = own_leaf_index;
871    }
872
873    #[cfg(test)]
874    pub(crate) fn own_tree_position(&self) -> TreePosition {
875        TreePosition::new(self.group_id().clone(), self.own_leaf_index())
876    }
877
878    #[cfg(test)]
879    pub(crate) fn message_secrets_store(&self) -> &MessageSecretsStore {
880        &self.message_secrets_store
881    }
882
883    #[cfg(test)]
884    pub(crate) fn resumption_psk_store(&self) -> &ResumptionPskStore {
885        &self.resumption_psk_store
886    }
887
888    #[cfg(test)]
889    pub(crate) fn set_group_context(&mut self, group_context: GroupContext) {
890        self.public_group.set_group_context(group_context)
891    }
892
893    #[cfg(any(test, feature = "test-utils"))]
894    pub fn ensure_persistence(&self, storage: &impl StorageProvider) -> Result<(), LibraryError> {
895        let loaded = MlsGroup::load(storage, self.group_id())
896            .map_err(|_| LibraryError::custom("Failed to load group from storage"))?;
897        let other = loaded.ok_or_else(|| LibraryError::custom("Group not found in storage"))?;
898
899        if self != &other {
900            let mut diagnostics = Vec::new();
901
902            if self.mls_group_config != other.mls_group_config {
903                diagnostics.push(format!(
904                    "mls_group_config:\n  Current: {:?}\n  Loaded:  {:?}",
905                    self.mls_group_config, other.mls_group_config
906                ));
907            }
908            if self.public_group != other.public_group {
909                diagnostics.push(format!(
910                    "public_group:\n  Current: {:?}\n  Loaded:  {:?}",
911                    self.public_group, other.public_group
912                ));
913            }
914            if self.group_epoch_secrets != other.group_epoch_secrets {
915                diagnostics.push(format!(
916                    "group_epoch_secrets:\n  Current: {:?}\n  Loaded:  {:?}",
917                    self.group_epoch_secrets, other.group_epoch_secrets
918                ));
919            }
920            if self.own_leaf_index != other.own_leaf_index {
921                diagnostics.push(format!(
922                    "own_leaf_index:\n  Current: {:?}\n  Loaded:  {:?}",
923                    self.own_leaf_index, other.own_leaf_index
924                ));
925            }
926            if self.message_secrets_store != other.message_secrets_store {
927                diagnostics.push(format!(
928                    "message_secrets_store:\n  Current: {:?}\n  Loaded:  {:?}",
929                    self.message_secrets_store, other.message_secrets_store
930                ));
931            }
932            if self.resumption_psk_store != other.resumption_psk_store {
933                diagnostics.push(format!(
934                    "resumption_psk_store:\n  Current: {:?}\n  Loaded:  {:?}",
935                    self.resumption_psk_store, other.resumption_psk_store
936                ));
937            }
938            if self.own_leaf_nodes != other.own_leaf_nodes {
939                diagnostics.push(format!(
940                    "own_leaf_nodes:\n  Current: {:?}\n  Loaded:  {:?}",
941                    self.own_leaf_nodes, other.own_leaf_nodes
942                ));
943            }
944            if self.aad != other.aad {
945                diagnostics.push(format!(
946                    "aad:\n  Current: {:?}\n  Loaded:  {:?}",
947                    self.aad, other.aad
948                ));
949            }
950            if self.group_state != other.group_state {
951                diagnostics.push(format!(
952                    "group_state:\n  Current: {:?}\n  Loaded:  {:?}",
953                    self.group_state, other.group_state
954                ));
955            }
956            #[cfg(feature = "extensions-draft-08")]
957            if self.application_export_tree != other.application_export_tree {
958                diagnostics.push(format!(
959                    "application_export_tree:\n  Current: {:?}\n  Loaded:  {:?}",
960                    self.application_export_tree, other.application_export_tree
961                ));
962            }
963
964            log::error!(
965                "Loaded group does not match current group! Differing fields ({}):\n\n{}",
966                diagnostics.len(),
967                diagnostics.join("\n\n")
968            );
969
970            return Err(LibraryError::custom(
971                "Loaded group does not match current group",
972            ));
973        }
974
975        Ok(())
976    }
977}
978
979/// A [`StagedWelcome`] can be inspected and then turned into a [`MlsGroup`].
980/// This allows checking who authored the Welcome message.
981#[derive(Debug)]
982pub struct StagedWelcome {
983    // The group configuration. See [`MlsGroupJoinConfig`] for more information.
984    mls_group_config: MlsGroupJoinConfig,
985    public_group: PublicGroup,
986    group_epoch_secrets: GroupEpochSecrets,
987    own_leaf_index: LeafNodeIndex,
988
989    /// A [`MessageSecretsStore`] that stores message secrets.
990    /// By default this store has the length of 1, i.e. only the [`MessageSecrets`]
991    /// of the current epoch is kept.
992    /// If more secrets from past epochs should be kept in order to be
993    /// able to decrypt application messages from previous epochs, the size of
994    /// the store must be increased through [`max_past_epochs()`].
995    message_secrets_store: MessageSecretsStore,
996
997    /// A secret that is not stored as part of the [`MlsGroup`] after the group is created.
998    /// It can be used by the application to derive forward secure secrets.
999    #[cfg(feature = "extensions-draft-08")]
1000    application_export_secret: ApplicationExportSecret,
1001
1002    /// Resumption psk store. This is where the resumption psks are kept in a rollover list.
1003    resumption_psk_store: ResumptionPskStore,
1004
1005    /// The [`VerifiableGroupInfo`] from the [`Welcome`] message.
1006    verifiable_group_info: VerifiableGroupInfo,
1007
1008    /// The key package bundle used for this welcome.
1009    key_package_bundle: KeyPackageBundle,
1010
1011    /// If we got a path secret, these are the derived path keys.
1012    path_keypairs: Option<Vec<EncryptionKeyPair>>,
1013}
1014
1015/// A `Welcome` message that has been processed but not staged yet.
1016///
1017/// This may be used in order to retrieve information from the `Welcome` about
1018/// the ratchet tree and PSKs.
1019///
1020/// Use `into_staged_welcome` to stage it into a [`StagedWelcome`].
1021pub struct ProcessedWelcome {
1022    // The group configuration. See [`MlsGroupJoinConfig`] for more information.
1023    mls_group_config: MlsGroupJoinConfig,
1024
1025    // The following is the state after parsing the Welcome message, before actually
1026    // building the group.
1027    ciphersuite: Ciphersuite,
1028    group_secrets: GroupSecrets,
1029    key_schedule: crate::schedule::KeySchedule,
1030    verifiable_group_info: crate::messages::group_info::VerifiableGroupInfo,
1031    resumption_psk_store: crate::schedule::psk::store::ResumptionPskStore,
1032    key_package_bundle: KeyPackageBundle,
1033}
openmls/group/mls_group/mod.rs

openmls/group/mls_group/
mod.rs
