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

matrix_sdk_crypto/olm/group_sessions/
mod.rs
