matrix_sdk_crypto/olm/group_sessions/
mod.rs

1// Copyright 2020 The Matrix.org Foundation C.I.C.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use ruma::{DeviceKeyAlgorithm, OwnedRoomId};
16use serde::{Deserialize, Serialize};
17
18mod forwarder_data;
19mod inbound;
20mod outbound;
21mod sender_data;
22pub(crate) mod sender_data_finder;
23
24pub use forwarder_data::ForwarderData;
25pub use inbound::{InboundGroupSession, PickledInboundGroupSession};
26pub(crate) use outbound::ShareState;
27pub use outbound::{
28    EncryptionSettings, OutboundGroupSession, OutboundGroupSessionEncryptionResult,
29    PickledOutboundGroupSession, ShareInfo,
30};
31pub use sender_data::{KnownSenderData, SenderData, SenderDataType};
32use thiserror::Error;
33pub use vodozemac::megolm::{ExportedSessionKey, SessionKey};
34use vodozemac::{Curve25519PublicKey, megolm::SessionKeyDecodeError};
35
36#[cfg(feature = "experimental-algorithms")]
37use crate::types::events::forwarded_room_key::ForwardedMegolmV2AesSha2Content;
38use crate::types::{
39    EventEncryptionAlgorithm, RoomKeyExport, SigningKey, SigningKeys, deserialize_curve_key,
40    deserialize_curve_key_vec,
41    events::forwarded_room_key::{ForwardedMegolmV1AesSha2Content, ForwardedRoomKeyContent},
42    serialize_curve_key, serialize_curve_key_vec,
43};
44
45/// An error type for the creation of group sessions.
46#[derive(Debug, Error)]
47pub enum SessionCreationError {
48    /// The provided algorithm is not supported.
49    #[error("The provided algorithm is not supported: {0}")]
50    Algorithm(EventEncryptionAlgorithm),
51    /// The room key key couldn't be decoded.
52    #[error(transparent)]
53    Decode(#[from] SessionKeyDecodeError),
54}
55
56/// An error type for the export of inbound group sessions.
57///
58/// Exported inbound group sessions will be either uploaded as backups, sent as
59/// `m.forwarded_room_key`s, or exported into a file backup.
60#[derive(Debug, Error)]
61pub enum SessionExportError {
62    /// The provided algorithm is not supported.
63    #[error("The provided algorithm is not supported: {0}")]
64    Algorithm(EventEncryptionAlgorithm),
65    /// The session export is missing a claimed Ed25519 sender key.
66    #[error("The provided room key export is missing a claimed Ed25519 sender key")]
67    MissingEd25519Key,
68}
69
70/// An exported version of an [`InboundGroupSession`].
71///
72/// This can be used to share the `InboundGroupSession` in an exported file.
73///
74/// See <https://spec.matrix.org/v1.13/client-server-api/#key-export-format>.
75#[derive(Deserialize, Serialize)]
76#[allow(missing_debug_implementations)]
77pub struct ExportedRoomKey {
78    /// The encryption algorithm that the session uses.
79    pub algorithm: EventEncryptionAlgorithm,
80
81    /// The room where the session is used.
82    pub room_id: OwnedRoomId,
83
84    /// The Curve25519 key of the device which initiated the session originally.
85    #[serde(deserialize_with = "deserialize_curve_key", serialize_with = "serialize_curve_key")]
86    pub sender_key: Curve25519PublicKey,
87
88    /// The ID of the session that the key is for.
89    pub session_id: String,
90
91    /// The key for the session.
92    pub session_key: ExportedSessionKey,
93
94    /// The Ed25519 key of the device which initiated the session originally.
95    #[serde(default)]
96    pub sender_claimed_keys: SigningKeys<DeviceKeyAlgorithm>,
97
98    /// Chain of Curve25519 keys through which this session was forwarded, via
99    /// m.forwarded_room_key events.
100    #[serde(
101        default,
102        deserialize_with = "deserialize_curve_key_vec",
103        serialize_with = "serialize_curve_key_vec"
104    )]
105    pub forwarding_curve25519_key_chain: Vec<Curve25519PublicKey>,
106
107    /// Whether this [`ExportedRoomKey`] can be shared with users who are
108    /// invited to the room in the future, allowing access to history, as
109    /// defined in [MSC3061].
110    ///
111    /// [MSC3061]: https://github.com/matrix-org/matrix-spec-proposals/pull/3061
112    #[serde(default, rename = "org.matrix.msc3061.shared_history")]
113    pub shared_history: bool,
114}
115
116impl ExportedRoomKey {
117    /// Create an `ExportedRoomKey` from a `BackedUpRoomKey`.
118    ///
119    /// This can be used when importing the keys from a backup into the store.
120    pub fn from_backed_up_room_key(
121        room_id: OwnedRoomId,
122        session_id: String,
123        room_key: BackedUpRoomKey,
124    ) -> Self {
125        let BackedUpRoomKey {
126            algorithm,
127            sender_key,
128            session_key,
129            sender_claimed_keys,
130            forwarding_curve25519_key_chain,
131            shared_history,
132        } = room_key;
133
134        Self {
135            algorithm,
136            room_id,
137            sender_key,
138            session_id,
139            session_key,
140            sender_claimed_keys,
141            forwarding_curve25519_key_chain,
142            shared_history,
143        }
144    }
145}
146
147impl RoomKeyExport for &ExportedRoomKey {
148    fn room_id(&self) -> &ruma::RoomId {
149        &self.room_id
150    }
151
152    fn session_id(&self) -> &str {
153        &self.session_id
154    }
155
156    fn sender_key(&self) -> Curve25519PublicKey {
157        self.sender_key
158    }
159}
160
161/// A backed up version of an [`InboundGroupSession`].
162///
163/// This can be used to back up the [`InboundGroupSession`] to the server using
164/// [server-side key backups].
165///
166/// See <https://spec.matrix.org/v1.13/client-server-api/#definition-backedupsessiondata>.
167///
168/// [server-side key backups]: https://spec.matrix.org/v1.13/client-server-api/#server-side-key-backups
169#[derive(Deserialize, Serialize)]
170#[allow(missing_debug_implementations)]
171pub struct BackedUpRoomKey {
172    /// The encryption algorithm that the session uses.
173    pub algorithm: EventEncryptionAlgorithm,
174
175    /// The Curve25519 key of the device which initiated the session originally.
176    #[serde(deserialize_with = "deserialize_curve_key", serialize_with = "serialize_curve_key")]
177    pub sender_key: Curve25519PublicKey,
178
179    /// The key for the session.
180    pub session_key: ExportedSessionKey,
181
182    /// The Ed25519 key of the device which initiated the session originally.
183    pub sender_claimed_keys: SigningKeys<DeviceKeyAlgorithm>,
184
185    /// Chain of Curve25519 keys through which this session was forwarded, via
186    /// `m.forwarded_room_key` events.
187    #[serde(
188        default,
189        deserialize_with = "deserialize_curve_key_vec",
190        serialize_with = "serialize_curve_key_vec"
191    )]
192    pub forwarding_curve25519_key_chain: Vec<Curve25519PublicKey>,
193
194    /// Whether this [`BackedUpRoomKey`] can be shared with users who are
195    /// invited to the room in the future, allowing access to history, as
196    /// defined in [MSC3061].
197    ///
198    /// [MSC3061]: https://github.com/matrix-org/matrix-spec-proposals/pull/3061
199    #[serde(default, rename = "org.matrix.msc3061.shared_history")]
200    pub shared_history: bool,
201}
202
203impl TryFrom<ExportedRoomKey> for ForwardedRoomKeyContent {
204    type Error = SessionExportError;
205
206    /// Convert an exported room key into a content for a forwarded room key
207    /// event.
208    ///
209    /// This will fail if the exported room key doesn't contain an Ed25519
210    /// claimed sender key.
211    fn try_from(room_key: ExportedRoomKey) -> Result<ForwardedRoomKeyContent, Self::Error> {
212        match room_key.algorithm {
213            EventEncryptionAlgorithm::MegolmV1AesSha2 => {
214                // The forwarded room key content only supports a single claimed sender
215                // key and it requires it to be a Ed25519 key. This here will be lossy
216                // conversion since we're dropping all other key types.
217                //
218                // This was fixed by the megolm v2 content. Hopefully we'll deprecate megolm v1
219                // before we have multiple signing keys.
220                if let Some(SigningKey::Ed25519(claimed_ed25519_key)) =
221                    room_key.sender_claimed_keys.get(&DeviceKeyAlgorithm::Ed25519)
222                {
223                    Ok(ForwardedRoomKeyContent::MegolmV1AesSha2(
224                        ForwardedMegolmV1AesSha2Content {
225                            room_id: room_key.room_id,
226                            session_id: room_key.session_id,
227                            session_key: room_key.session_key,
228                            claimed_sender_key: room_key.sender_key,
229                            claimed_ed25519_key: *claimed_ed25519_key,
230                            forwarding_curve25519_key_chain: room_key
231                                .forwarding_curve25519_key_chain
232                                .clone(),
233                            other: Default::default(),
234                        }
235                        .into(),
236                    ))
237                } else {
238                    Err(SessionExportError::MissingEd25519Key)
239                }
240            }
241            #[cfg(feature = "experimental-algorithms")]
242            EventEncryptionAlgorithm::MegolmV2AesSha2 => {
243                Ok(ForwardedRoomKeyContent::MegolmV2AesSha2(
244                    ForwardedMegolmV2AesSha2Content {
245                        room_id: room_key.room_id,
246                        session_id: room_key.session_id,
247                        session_key: room_key.session_key,
248                        claimed_sender_key: room_key.sender_key,
249                        claimed_signing_keys: room_key.sender_claimed_keys,
250                        other: Default::default(),
251                    }
252                    .into(),
253                ))
254            }
255            _ => Err(SessionExportError::Algorithm(room_key.algorithm)),
256        }
257    }
258}
259
260impl From<ExportedRoomKey> for BackedUpRoomKey {
261    fn from(value: ExportedRoomKey) -> Self {
262        let ExportedRoomKey {
263            algorithm,
264            room_id: _,
265            sender_key,
266            session_id: _,
267            session_key,
268            sender_claimed_keys,
269            forwarding_curve25519_key_chain,
270            shared_history,
271        } = value;
272
273        Self {
274            algorithm,
275            sender_key,
276            session_key,
277            sender_claimed_keys,
278            forwarding_curve25519_key_chain,
279            shared_history,
280        }
281    }
282}
283
284impl TryFrom<ForwardedRoomKeyContent> for ExportedRoomKey {
285    type Error = SessionExportError;
286
287    /// Convert the content of a forwarded room key into a exported room key.
288    fn try_from(forwarded_key: ForwardedRoomKeyContent) -> Result<Self, Self::Error> {
289        let algorithm = forwarded_key.algorithm();
290
291        match forwarded_key {
292            ForwardedRoomKeyContent::MegolmV1AesSha2(content) => {
293                let mut sender_claimed_keys = SigningKeys::new();
294                sender_claimed_keys
295                    .insert(DeviceKeyAlgorithm::Ed25519, content.claimed_ed25519_key.into());
296
297                Ok(Self {
298                    algorithm,
299                    room_id: content.room_id,
300                    session_id: content.session_id,
301                    forwarding_curve25519_key_chain: content.forwarding_curve25519_key_chain,
302                    sender_claimed_keys,
303                    sender_key: content.claimed_sender_key,
304                    session_key: content.session_key,
305                    shared_history: false,
306                })
307            }
308            #[cfg(feature = "experimental-algorithms")]
309            ForwardedRoomKeyContent::MegolmV2AesSha2(content) => Ok(Self {
310                algorithm,
311                room_id: content.room_id,
312                session_id: content.session_id,
313                forwarding_curve25519_key_chain: Default::default(),
314                sender_claimed_keys: content.claimed_signing_keys,
315                sender_key: content.claimed_sender_key,
316                session_key: content.session_key,
317                shared_history: false,
318            }),
319            ForwardedRoomKeyContent::Unknown(c) => Err(SessionExportError::Algorithm(c.algorithm)),
320        }
321    }
322}
323
324#[cfg(test)]
325mod tests {
326    use serde_json::json;
327
328    use super::BackedUpRoomKey;
329
330    #[test]
331    fn test_deserialize_backed_up_key() {
332        let data = json!({
333                "algorithm": "m.megolm.v1.aes-sha2",
334                "room_id": "!room:id",
335                "sender_key": "FOvlmz18LLI3k/llCpqRoKT90+gFF8YhuL+v1YBXHlw",
336                "session_id": "/2K+V777vipCxPZ0gpY9qcpz1DYaXwuMRIu0UEP0Wa0",
337                "session_key": "AQAAAAAclzWVMeWBKH+B/WMowa3rb4ma3jEl6n5W4GCs9ue65CruzD3ihX+85pZ9hsV9Bf6fvhjp76WNRajoJYX0UIt7aosjmu0i+H+07hEQ0zqTKpVoSH0ykJ6stAMhdr6Q4uW5crBmdTTBIsqmoWsNJZKKoE2+ldYrZ1lrFeaJbjBIY/9ivle++74qQsT2dIKWPanKc9Q2Gl8LjESLtFBD9Fmt",
338                "sender_claimed_keys": {
339                    "ed25519": "F4P7f1Z0RjbiZMgHk1xBCG3KC4/Ng9PmxLJ4hQ13sHA"
340                },
341                "forwarding_curve25519_key_chain": ["DBPC2zr6c9qimo9YRFK3RVr0Two/I6ODb9mbsToZN3Q", "bBc/qzZFOOKshMMT+i4gjS/gWPDoKfGmETs9yfw9430"]
342        });
343
344        let backed_up_room_key: BackedUpRoomKey = serde_json::from_value(data)
345            .expect("We should be able to deserialize the backed up room key.");
346        assert_eq!(
347            backed_up_room_key.forwarding_curve25519_key_chain.len(),
348            2,
349            "The number of forwarding Curve25519 chains should be two."
350        );
351    }
352}
matrix_sdk_crypto/olm/group_sessions/mod.rs

matrix_sdk_crypto/olm/group_sessions/
mod.rs
