feat(crypto-js): Implement `OlmMachine.export_room_keys` and `.import_room_keys`

feat(crypto-js): Implement `OlmMachine.export_room_keys` and `.import_room_keys`

bindings/matrix-sdk-crypto-js/src/machine.rs

@@ -2,9 +2,9 @@
 
 use std::collections::BTreeMap;
 
-use js_sys::{Array, Map, Promise, Set};
+use js_sys::{Array, Function, Map, Promise, Set};
 use ruma::{serde::Raw, DeviceKeyAlgorithm, OwnedTransactionId, UInt};
-use serde_json::Value as JsonValue;
+use serde_json::{json, Value as JsonValue};
 use wasm_bindgen::prelude::*;
 
 use crate::{
@@ -626,4 +626,106 @@ impl OlmMachine {
                 .map(|_| JsValue::UNDEFINED)?)
         }))
     }
+
+    /// Export the keys that match the given predicate.
+    ///
+    /// `predicate` is a closure that will be called for every known
+    /// `InboundGroupSession`, which represents a room key. If the closure
+    /// returns `true`, the `InboundGroupSession` will be included in the
+    /// export, otherwise it won't.
+    #[wasm_bindgen(js_name = "exportRoomKeys")]
+    pub fn export_room_keys(&self, predicate: Function) -> Promise {
+        let me = self.inner.clone();
+
+        future_to_promise(async move {
+            Ok(serde_json::to_string(
+                &me.export_room_keys(|session| {
+                    let session = session.clone();
+
+                    predicate
+                        .call1(&JsValue::NULL, &olm::InboundGroupSession::from(session).into())
+                        .expect("Predicate function passed to `export_room_keys` failed")
+                        .as_bool()
+                        .unwrap_or(false)
+                })
+                .await?,
+            )?)
+        })
+    }
+
+    /// Import the given room keys into our store.
+    ///
+    /// `exported_keys` is a list of previously exported keys that should be
+    /// imported into our store. If we already have a better version of a key,
+    /// the key will _not_ be imported.
+    ///
+    /// `progress_listener` is a closure that takes 2 arguments: `progress` and
+    /// `total`, and returns nothing.
+    #[wasm_bindgen(js_name = "importRoomKeys")]
+    pub fn import_room_keys(
+        &self,
+        exported_room_keys: &str,
+        progress_listener: Function,
+    ) -> Result<Promise, JsError> {
+        let me = self.inner.clone();
+        let exported_room_keys: Vec<matrix_sdk_crypto::olm::ExportedRoomKey> =
+            serde_json::from_str(exported_room_keys)?;
+
+        Ok(future_to_promise(async move {
+            let matrix_sdk_crypto::RoomKeyImportResult { imported_count, total_count, keys } = me
+                .import_room_keys(exported_room_keys, false, |progress, total| {
+                    let progress: u64 = progress.try_into().unwrap();
+                    let total: u64 = total.try_into().unwrap();
+
+                    progress_listener
+                        .call2(&JsValue::NULL, &JsValue::from(progress), &JsValue::from(total))
+                        .expect("Progress listener passed to `import_room_keys` failed");
+                })
+                .await?;
+
+            Ok(serde_json::to_string(&json!({
+                "imported_count": imported_count,
+                "total_count": total_count,
+                "keys": keys,
+            }))?)
+        }))
+    }
+
+    /// Encrypt the list of exported room keys using the given passphrase.
+    ///
+    /// `exported_room_keys` is a list of sessions that should be encrypted
+    /// (it's generally returned by `export_room_keys`). `passphrase` is the
+    /// passphrase that will be used to encrypt the exported room keys. And
+    /// `rounds` is the number of rounds that should be used for the key
+    /// derivation when the passphrase gets turned into an AES key. More rounds
+    /// are increasingly computationnally intensive and as such help against
+    /// brute-force attacks. Should be at least `10_000`, while values in the
+    /// `100_000` ranges should be preferred.
+    #[wasm_bindgen(js_name = "encryptExportedRoomKeys")]
+    pub fn encrypt_exported_room_keys(
+        exported_room_keys: &str,
+        passphrase: &str,
+        rounds: u32,
+    ) -> Result<String, JsError> {
+        let exported_room_keys: Vec<matrix_sdk_crypto::olm::ExportedRoomKey> =
+            serde_json::from_str(exported_room_keys)?;
+
+        Ok(matrix_sdk_crypto::encrypt_room_key_export(&exported_room_keys, passphrase, rounds)?)
+    }
+
+    /// Try to decrypt a reader into a list of exported room keys.
+    ///
+    /// `encrypted_exported_room_keys` is the result from
+    /// `encrypt_exported_room_keys`. `passphrase` is the passphrase that was
+    /// used when calling `encrypt_exported_room_keys`.
+    #[wasm_bindgen(js_name = "decryptExportedRoomKeys")]
+    pub fn decrypt_exported_room_keys(
+        encrypted_exported_room_keys: &str,
+        passphrase: &str,
+    ) -> Result<String, JsError> {
+        Ok(serde_json::to_string(&matrix_sdk_crypto::decrypt_room_key_export(
+            encrypted_exported_room_keys.as_bytes(),
+            passphrase,
+        )?)?)
+    }
 }

bindings/matrix-sdk-crypto-js/src/olm.rs

@@ -2,7 +2,7 @@
 
 use wasm_bindgen::prelude::*;
 
-use crate::impl_from_to_inner;
+use crate::{identifiers, impl_from_to_inner};
 
 /// Struct representing the state of our private cross signing keys,
 /// it shows which private cross signing keys we have locally stored.
@@ -36,3 +36,37 @@ impl CrossSigningStatus {
         self.inner.has_user_signing
     }
 }
+
+/// Inbound group session.
+///
+/// Inbound group sessions are used to exchange room messages between a group of
+/// participants. Inbound group sessions are used to decrypt the room messages.
+#[wasm_bindgen]
+#[derive(Debug)]
+pub struct InboundGroupSession {
+    inner: matrix_sdk_crypto::olm::InboundGroupSession,
+}
+
+impl_from_to_inner!(matrix_sdk_crypto::olm::InboundGroupSession => InboundGroupSession);
+
+#[wasm_bindgen]
+impl InboundGroupSession {
+    /// The room where this session is used in.
+    #[wasm_bindgen(getter, js_name = "roomId")]
+    pub fn room_id(&self) -> identifiers::RoomId {
+        self.inner.room_id().to_owned().into()
+    }
+
+    /// Returns the unique identifier for this session.
+    #[wasm_bindgen(getter, js_name = "sessionId")]
+    pub fn session_id(&self) -> String {
+        self.inner.session_id().to_owned()
+    }
+
+    /// Has the session been imported from a file or server-side backup? As
+    /// opposed to being directly received as an `m.room_key` event.
+    #[wasm_bindgen(js_name = "hasBeenImported")]
+    pub fn has_been_imported(&self) -> bool {
+        self.inner.has_been_imported()
+    }
+}

bindings/matrix-sdk-crypto-js/tests/device.test.js

@@ -28,7 +28,6 @@ const {
     QrCode,
     QrCodeScan,
 } = require('../pkg/matrix_sdk_crypto_js');
-const { LoggerLevel, Tracing } = require('../pkg/matrix_sdk_crypto_js');
 const { zip, addMachineToMachine } = require('./helper');
 
 describe('LocalTrust', () => {

bindings/matrix-sdk-crypto-js/tests/machine.test.js

@@ -5,6 +5,7 @@ const {
     DeviceKeyId,
     DeviceLists,
     EncryptionSettings,
+    InboundGroupSession,
     KeysClaimRequest,
     KeysQueryRequest,
     KeysUploadRequest,
@@ -19,6 +20,7 @@ const {
     VerificationRequest,
     VerificationState,
 } = require('../pkg/matrix_sdk_crypto_js');
+const { addMachineToMachine } = require('./helper');
 require('fake-indexeddb/auto');
 
 describe(OlmMachine.name, () => {
@@ -491,4 +493,77 @@ describe(OlmMachine.name, () => {
 
         expect(isTrusted).toStrictEqual(false);
     });
+
+    describe('can export/import room keys', () => {
+        let m;
+        let exportedRoomKeys;
+
+        test('can export room keys', async () => {
+            m = await machine();
+            await m.shareRoomKey(room, [new UserId('@bob:example.org')], new EncryptionSettings());
+
+            exportedRoomKeys = await m.exportRoomKeys(session => {
+                expect(session).toBeInstanceOf(InboundGroupSession);
+                expect(session.roomId.toString()).toStrictEqual(room.toString());
+                expect(session.sessionId).toBeDefined();
+                expect(session.hasBeenImported()).toStrictEqual(false);
+
+                return true;
+            });
+
+            const roomKeys = JSON.parse(exportedRoomKeys);
+            expect(roomKeys).toHaveLength(1);
+            expect(roomKeys[0]).toMatchObject({
+                algorithm: expect.any(String),
+                room_id: room.toString(),
+                sender_key: expect.any(String),
+                session_id: expect.any(String),
+                session_key: expect.any(String),
+                sender_claimed_keys: {
+                    ed25519: expect.any(String),
+                },
+                forwarding_curve25519_key_chain: [],
+            });
+        });
+
+        let encryptedExportedRoomKeys;
+        let encryptionPassphrase = 'Hello, Matrix!';
+
+        test('can encrypt the exported room keys', () => {
+            encryptedExportedRoomKeys = OlmMachine.encryptExportedRoomKeys(
+                exportedRoomKeys,
+                encryptionPassphrase,
+                100_000,
+            );
+
+            expect(encryptedExportedRoomKeys).toMatch(/^-----BEGIN MEGOLM SESSION DATA-----/);
+        });
+
+        test('can decrypt the exported room keys', () => {
+            const decryptedExportedRoomKeys = OlmMachine.decryptExportedRoomKeys(
+                encryptedExportedRoomKeys,
+                encryptionPassphrase,
+            );
+
+            expect(decryptedExportedRoomKeys).toStrictEqual(exportedRoomKeys);
+        });
+
+        test('can import room keys', async () => {
+            const progressListener = (progress, total) => {
+                expect(progress).toBeLessThan(total);
+
+                // Since it's called only once, let's be crazy.
+                expect(progress).toStrictEqual(0n);
+                expect(total).toStrictEqual(1n);
+            };
+
+            const result = JSON.parse(await m.importRoomKeys(exportedRoomKeys, progressListener));
+
+            expect(result).toMatchObject({
+                imported_count: expect.any(Number),
+                total_count: expect.any(Number),
+                keys: expect.any(Object),
+            });
+        });
+    });
 });