From 3941af93d23da81cd45669a9d4606521603301eb Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Thu, 17 Sep 2020 14:19:57 +0200
Subject: [PATCH] more impl of SessionBackup

---
 src/matrix/e2ee/megolm/SessionBackup.js | 16 ++++++++--------
 src/matrix/net/HomeServerApi.js         | 11 +++++++++++
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/matrix/e2ee/megolm/SessionBackup.js b/src/matrix/e2ee/megolm/SessionBackup.js
index 37db5e4b..3c6854f2 100644
--- a/src/matrix/e2ee/megolm/SessionBackup.js
+++ b/src/matrix/e2ee/megolm/SessionBackup.js
@@ -25,32 +25,32 @@ export class SessionBackup {
     }
 
     async getSession(roomId, sessionId) {
-        const sessionResponse = await this._hsApi.roomKey(this._backupInfo.version, roomId, sessionId).response();
-        let sessionInfo;
+        const sessionResponse = await this._hsApi.roomKeyForRoomAndSession(this._backupInfo.version, roomId, sessionId).response();
         const decryption = new this._olm.PkDecryption();
         try {
             decryption.init_with_private_key(this._privateKey);
-            sessionInfo = this._decryption.decrypt(
+            const sessionInfo = this._decryption.decrypt(
                 sessionResponse.session_data.ephemeral,
                 sessionResponse.session_data.mac,
                 sessionResponse.session_data.ciphertext,
             );
+            return JSON.parse(sessionInfo);
         } finally {
             decryption.free();
         }
-        return JSON.parse(sessionInfo);
     }
 
     static async fromSecretStorage({olm, secretStorage, hsApi}) {
-        const backupInfo = await hsApi.roomKeysVersion().response();
         const base64PrivateKey = await secretStorage.readSecret("m.megolm_backup.v1");
         if (base64PrivateKey) {
             const privateKey = base64.decode(base64PrivateKey);
+            const backupInfo = await hsApi.roomKeysVersion().response();
+            const expectedPubKey = backupInfo.auth_data.public_key;
             const decryption = new olm.PkDecryption();
             try {
-                const pubKey = decryption.init_with_private_key(this._privateKey);
-                if (pubKey !== backupInfo.auth_data.public_key) {
-                    throw new Error(`Bad backup key, public key does not match. Calculated ${pubKey} but expected ${backupInfo.auth_data.public_key}`);
+                const pubKey = decryption.init_with_private_key(privateKey);
+                if (pubKey !== expectedPubKey) {
+                    throw new Error(`Bad backup key, public key does not match. Calculated ${pubKey} but expected ${expectedPubKey}`);
                 }
             } finally {
                 decryption.free();
diff --git a/src/matrix/net/HomeServerApi.js b/src/matrix/net/HomeServerApi.js
index 649a7462..c536ecf7 100644
--- a/src/matrix/net/HomeServerApi.js
+++ b/src/matrix/net/HomeServerApi.js
@@ -176,6 +176,17 @@ export class HomeServerApi {
     sendToDevice(type, payload, txnId, options = null) {
         return this._put(`/sendToDevice/${encodeURIComponent(type)}/${encodeURIComponent(txnId)}`, null, payload, options);
     }
+    
+    roomKeysVersion(version = null, options = null) {
+        if (!version) {
+            version = "";
+        }
+        return this._get(`/room_keys/version/${encodeURIComponent(version)}`, null, null, options);
+    }
+
+    roomKeyForRoomAndSession(version, roomId, sessionId, options = null) {
+        return this._get(`/room_keys/keys/${encodeURIComponent(roomId)}/${encodeURIComponent(sessionId)}`, {version}, null, options);
+    }
 
     get mediaRepository() {
         return this._mediaRepository;