Expose the support to import and export a secrets bundle

Author: poljar

CHANGELOG.md

@@ -1,5 +1,9 @@
 # UNRELEASED
 
+-   Add `OlmMachine.importSecretsBundle()` and `OlmMachine.exportSecretsBundle()`
+    methods as well as the `SecretsBundle` class to import end-to-end encryption
+    secrets in a bundled manner.
+
 -   Expose the vodozemac ECIES support, which can be used to establish the secure
     channel required for QR code login described in [MSC4108](https://github.com/matrix-org/matrix-spec-proposals/pull/4108).
 

src/machine.rs

@@ -534,6 +534,49 @@ impl OlmMachine {
         })
     }
 
+    /// Export all the secrets we have in the store into a [`SecretsBundle`].
+    ///
+    /// This method will export all the private cross-signing keys and, if
+    /// available, the private part of a backup key and its accompanying
+    /// version.
+    ///
+    /// The method will fail if we don't have all three private cross-signing
+    /// keys available.
+    ///
+    /// **Warning**: Only export this and share it with a trusted recipient,
+    /// i.e. if an existing device is sharing this with a new device.
+    #[wasm_bindgen(js_name = "exportSecretsBundle")]
+    pub fn export_secrets_bundle(&self) -> Promise {
+        let me = self.inner.clone();
+
+        future_to_promise(async move {
+            Ok(me.store().export_secrets_bundle().await.map(store::SecretsBundle::from)?)
+        })
+    }
+
+    /// Import and persists secrets from a [`SecretsBundle`].
+    ///
+    /// This method will import all the private cross-signing keys and, if
+    /// available, the private part of a backup key and its accompanying
+    /// version into the store.
+    ///
+    /// **Warning**: Only import this from a trusted source, i.e. if an existing
+    /// device is sharing this with a new device. The imported cross-signing
+    /// keys will create a [`OwnUserIdentity`] and mark it as verified.
+    ///
+    /// The backup key will be persisted in the store and can be enabled using
+    /// the [`BackupMachine`].
+    #[wasm_bindgen(js_name = "importSecretsBundle")]
+    pub fn import_secrets_bundle(&self, bundle: store::SecretsBundle) -> Promise {
+        let me = self.inner.clone();
+
+        future_to_promise(async move {
+            me.store().import_secrets_bundle(&bundle.inner).await?;
+
+            Ok(JsValue::null())
+        })
+    }
+
     /// Export all the private cross signing keys we have.
     ///
     /// The export will contain the seeds for the ed25519 keys as

src/store.rs

@@ -2,7 +2,10 @@
 
 use std::sync::Arc;
 
-use matrix_sdk_crypto::store::{DynCryptoStore, IntoCryptoStore, MemoryStore};
+use matrix_sdk_crypto::{
+    store::{DynCryptoStore, IntoCryptoStore, MemoryStore},
+    types::BackupSecrets,
+};
 use wasm_bindgen::prelude::*;
 
 use crate::{
@@ -170,3 +173,69 @@ impl RoomKeyInfo {
         self.inner.session_id.clone()
     }
 }
+
+/// Struct containing the bundle of secrets to fully activate a new devices for
+/// end-to-end encryption.
+#[derive(Debug)]
+#[wasm_bindgen]
+pub struct SecretsBundle {
+    pub(super) inner: matrix_sdk_crypto::types::SecretsBundle,
+}
+
+/// The backup-specific parts of a secrets bundle.
+#[derive(Debug)]
+#[wasm_bindgen(getter_with_clone)]
+pub struct BackupSecretsBundle {
+    /// The backup decryption key.
+    pub key: String,
+    /// The backup version which this backup decryption key is used with.
+    pub backup_version: String,
+}
+
+#[wasm_bindgen]
+impl SecretsBundle {
+    /// The seed of the master key encoded as unpadded base64.
+    #[wasm_bindgen(getter, js_name = "masterKey")]
+    pub fn master_key(&self) -> String {
+        self.inner.cross_signing.master_key.clone()
+    }
+
+    /// The seed of the self signing key encoded as unpadded base64.
+    #[wasm_bindgen(getter, js_name = "selfSigningKey")]
+    pub fn self_signing_key(&self) -> String {
+        self.inner.cross_signing.self_signing_key.clone()
+    }
+
+    /// The seed of the user signing key encoded as unpadded base64.
+    #[wasm_bindgen(getter, js_name = "userSigningKey")]
+    pub fn user_signing_key(&self) -> String {
+        self.inner.cross_signing.user_signing_key.clone()
+    }
+
+    /// The bundle of the backup decryption key and backup version if any.
+    #[wasm_bindgen(getter, js_name = "backupBundle")]
+    pub fn backup_bundle(&self) -> Option<BackupSecretsBundle> {
+        if let Some(BackupSecrets::MegolmBackupV1Curve25519AesSha2(backup)) = &self.inner.backup {
+            Some(BackupSecretsBundle {
+                key: backup.key.to_base64(),
+                backup_version: backup.backup_version.clone(),
+            })
+        } else {
+            None
+        }
+    }
+
+    /// Serialize the [`SecretsBundle`] to a JSON object.
+    pub fn to_json(&self) -> Result<JsValue, JsError> {
+        Ok(serde_wasm_bindgen::to_value(&self.inner)?)
+    }
+
+    /// Deserialize the [`SecretsBundle`] from a JSON object.
+    pub fn from_json(json: JsValue) -> Result<SecretsBundle, JsError> {
+        let bundle = serde_wasm_bindgen::from_value(json)?;
+
+        Ok(Self { inner: bundle })
+    }
+}
+
+impl_from_to_inner!(matrix_sdk_crypto::types::SecretsBundle => SecretsBundle);

tests/ecies.test.ts

@@ -1,4 +1,4 @@
-const { Ecies } = require("../pkg/matrix_sdk_crypto_wasm");
+const { Ecies, SecretsBundle, UserId, DeviceId, OlmMachine, RequestType } = require("../pkg/matrix_sdk_crypto_wasm");
 
 describe(Ecies.name, () => {
     test("can establish a channel and decrypt the initial message", () => {
@@ -26,3 +26,65 @@ describe(Ecies.name, () => {
         expect(second_plaintext).toStrictEqual("Other message");
     });
 });
+
+describe(SecretsBundle.name, () => {
+    test("can deserialize a secrets bundle", async () => {
+        const json = {
+            type: "m.login.secrets",
+            cross_signing: {
+                master_key: "bMnVpkHI4S2wXRxy+IpaKM5PIAUUkl6DE+n0YLIW/qs",
+                user_signing_key: "8tlgLjUrrb/zGJo4YKGhDTIDCEjtJTAS/Sh2AGNLuIo",
+                self_signing_key: "pfDknmP5a0fVVRE54zhkUgJfzbNmvKcNfIWEW796bQs",
+            },
+            backup: {
+                algorithm: "m.megolm_backup.v1.curve25519-aes-sha2",
+                key: "bYYv3aFLQ49jMNcOjuTtBY9EKDby2x1m3gfX81nIKRQ",
+                backup_version: "9",
+            },
+        };
+
+        const cycle = JSON.parse(JSON.stringify(json));
+        const bundle = SecretsBundle.from_json(cycle);
+
+        expect(bundle.masterKey).toStrictEqual("bMnVpkHI4S2wXRxy+IpaKM5PIAUUkl6DE+n0YLIW/qs");
+    });
+
+    test("can import a secrets bundle", async () => {
+        const userId = new UserId("@alice:example.org");
+        const firstDevice = new DeviceId("ABCDEF");
+        const secondDevice = new DeviceId("DEVICE2");
+
+        const firstMachine = await OlmMachine.initialize(userId, firstDevice);
+        const secondMachine = await OlmMachine.initialize(userId, secondDevice);
+
+        await firstMachine.bootstrapCrossSigning(false);
+        const bundle = await firstMachine.exportSecretsBundle();
+
+        const alice = new Ecies();
+        const bob = new Ecies();
+
+        const json_bundle = bundle.to_json();
+
+        const { initial_message } = alice.establish_outbound_channel(bob.public_key(), JSON.stringify(json_bundle));
+        const { message } = bob.establish_inbound_channel(initial_message);
+
+        const deserialize_message = JSON.parse(message);
+        const received_bundle = SecretsBundle.from_json(deserialize_message);
+
+        await secondMachine.importSecretsBundle(received_bundle);
+
+        const crossSigningStatus = await secondMachine.crossSigningStatus();
+        expect(crossSigningStatus.hasMaster).toStrictEqual(true);
+        expect(crossSigningStatus.hasSelfSigning).toStrictEqual(true);
+        expect(crossSigningStatus.hasUserSigning).toStrictEqual(true);
+
+        const exported_bundle = await secondMachine.exportSecretsBundle();
+
+        expect(exported_bundle.masterKey).toStrictEqual(bundle.masterKey);
+        expect(exported_bundle.selfSigningKey).toStrictEqual(bundle.selfSigningKey);
+        expect(exported_bundle.userSigningKey).toStrictEqual(bundle.userSigningKey);
+
+        const identity = await secondMachine.getIdentity(userId);
+        expect(identity.isVerified).toBeTruthy();
+    });
+});