basic PoC of image decryption working

needs looooaaads of cleanup still

src/domain/session/room/timeline/TilesCollection.js

@@ -95,6 +95,9 @@ export class TilesCollection extends BaseObservableList {
 
     onUnsubscribeLast() {
         this._entrySubscription = this._entrySubscription();
+        for(let i = 0; i < this._tiles.length; i+= 1) {
+            this._tiles[i].dispose();
+        }
         this._tiles = null;
     }
 

src/domain/session/room/timeline/tiles/ImageTile.js

@@ -20,20 +20,47 @@ const MAX_HEIGHT = 300;
 const MAX_WIDTH = 400;
 
 export class ImageTile extends MessageTile {
+
+    constructor(options) {
+        super(options);
+        this._decryptedUrl = null;
+        this.load();
+    }
+
+    async load() {
+        const thumbnailFile = this._getContent().file;
+        if (thumbnailFile) {
+            const buffer = await this._mediaRepository.downloadEncryptedFile(thumbnailFile);
+            // TODO: fix XSS bug here by not checking mimetype
+            const blob = new Blob([buffer], {type: thumbnailFile.mimetype});
+            if (this.isDisposed) {
+                return;
+            }
+            this._decryptedUrl = URL.createObjectURL(blob);
+            this.emitChange("thumbnailUrl");
+        }
+    }
+
     get thumbnailUrl() {
+        if (this._decryptedUrl) {
+            return this._decryptedUrl;
+        }
         const mxcUrl = this._getContent()?.url;
         if (typeof mxcUrl === "string") {
             return this._mediaRepository.mxcUrlThumbnail(mxcUrl, this.thumbnailWidth, this.thumbnailHeight, "scale");
         }
-        return null;
+        return "";
     }
 
     get url() {
+        if (this._decryptedUrl) {
+            return this._decryptedUrl;
+        }
         const mxcUrl = this._getContent()?.url;
         if (typeof mxcUrl === "string") {
             return this._mediaRepository.mxcUrl(mxcUrl);
         }
-        return null;
+        return "";
     }
 
     _scaleFactor() {
@@ -62,4 +89,12 @@ export class ImageTile extends MessageTile {
     get shape() {
         return "image";
     }
+
+    dispose() {
+        if (this._decryptedUrl) {
+            URL.revokeObjectURL(this._decryptedUrl);
+            this._decryptedUrl = null;
+        }
+        super.dispose();
+    }
 }

src/matrix/SessionContainer.js

@@ -168,6 +168,11 @@ export class SessionContainer {
         }
         this._requestScheduler = new RequestScheduler({hsApi, clock: this._clock});
         this._requestScheduler.start();
+        const mediaRepository = new MediaRepository({
+            homeServer: sessionInfo.homeServer,
+            cryptoDriver: this._cryptoDriver,
+            request: this._request,
+        });
         this._session = new Session({
             storage: this._storage,
             sessionInfo: filteredSessionInfo,
@@ -176,7 +181,7 @@ export class SessionContainer {
             clock: this._clock,
             olmWorker,
             cryptoDriver: this._cryptoDriver,
-            mediaRepository: new MediaRepository(sessionInfo.homeServer)
+            mediaRepository
         });
         await this._session.load();
         if (isNewLogin) {

src/matrix/net/HomeServerApi.js

@@ -75,7 +75,8 @@ export class HomeServerApi {
             method,
             headers,
             body: bodyString,
-            timeout: options?.timeout
+            timeout: options?.timeout,
+            format: "json"
         });
 
         const wrapper = new RequestWrapper(method, url, requestResult);

src/matrix/net/MediaRepository.js

@@ -15,17 +15,20 @@ limitations under the License.
 */
 
 import {encodeQueryParams} from "./common.js";
+import {decryptAttachment} from "../e2ee/attachment.js";
 
 export class MediaRepository {
-    constructor(homeserver) {
+    constructor({homeServer, cryptoDriver, request}) {
-        this._homeserver = homeserver;
+        this._homeServer = homeServer;
+        this._cryptoDriver = cryptoDriver;
+        this._request = request;
     }
 
     mxcUrlThumbnail(url, width, height, method) {
         const parts = this._parseMxcUrl(url);
         if (parts) {
             const [serverName, mediaId] = parts;
-            const httpUrl = `${this._homeserver}/_matrix/media/r0/thumbnail/${encodeURIComponent(serverName)}/${encodeURIComponent(mediaId)}`;
+            const httpUrl = `${this._homeServer}/_matrix/media/r0/thumbnail/${encodeURIComponent(serverName)}/${encodeURIComponent(mediaId)}`;
             return httpUrl + "?" + encodeQueryParams({width, height, method});
         }
         return null;
@@ -35,7 +38,7 @@ export class MediaRepository {
         const parts = this._parseMxcUrl(url);
         if (parts) {
             const [serverName, mediaId] = parts;
-            return `${this._homeserver}/_matrix/media/r0/download/${encodeURIComponent(serverName)}/${encodeURIComponent(mediaId)}`;
+            return `${this._homeServer}/_matrix/media/r0/download/${encodeURIComponent(serverName)}/${encodeURIComponent(mediaId)}`;
         } else {
             return null;
         }
@@ -49,4 +52,11 @@ export class MediaRepository {
             return null;
         }
     }
+
+    async downloadEncryptedFile(fileEntry) {
+        const url = this.mxcUrl(fileEntry.url);
+        const {body: encryptedBuffer} = await this._request(url, {format: "buffer"}).response();
+        const decryptedBuffer = await decryptAttachment(this._cryptoDriver, encryptedBuffer, fileEntry);
+        return decryptedBuffer;
+    }
 }

src/matrix/net/request/fetch.js

@@ -51,8 +51,9 @@ class RequestResult {
 }
 
 export function createFetchRequest(createTimeout) {
-    return function fetchRequest(url, options) {
+    return function fetchRequest(url, {method, headers, body, timeout, format}) {
         const controller = typeof AbortController === "function" ? new AbortController() : null;
+        let options = {method, body};
         if (controller) {
             options = Object.assign(options, {
                 signal: controller.signal
@@ -76,18 +77,22 @@ export function createFetchRequest(createTimeout) {
             // cache: "no-store",
             cache: "default",
         });
-        if (options.headers) {
+        if (headers) {
-            const headers = new Headers();
+            const fetchHeaders = new Headers();
-            for(const [name, value] of options.headers.entries()) {
+            for(const [name, value] of headers.entries()) {
-                headers.append(name, value);
+                fetchHeaders.append(name, value);
             }
-            options.headers = headers;
+            options.headers = fetchHeaders;
         }
         const promise = fetch(url, options).then(async response => {
             const {status} = response;
             let body;
             try {
-                body = await response.json();
+                if (format === "json") {
+                    body = await response.json();
+                } else if (format === "buffer") {
+                    body = await response.arrayBuffer();
+                }
             } catch (err) {
                 // some error pages return html instead of json, ignore error
                 if (!(err.name === "SyntaxError" && status >= 400)) {
@@ -105,14 +110,14 @@ export function createFetchRequest(createTimeout) {
                 // 
                 // One could check navigator.onLine to rule out the first
                 // but the 2 latter ones are indistinguishable from javascript.
-                throw new ConnectionError(`${options.method} ${url}: ${err.message}`);
+                throw new ConnectionError(`${method} ${url}: ${err.message}`);
             }
             throw err;
         });
         const result = new RequestResult(promise, controller);
 
-        if (options.timeout) {
+        if (timeout) {
-            result.promise = abortOnTimeout(createTimeout, options.timeout, result, result.promise);
+            result.promise = abortOnTimeout(createTimeout, timeout, result, result.promise);
         }
 
         return result;

src/matrix/ssss/SecretStorage.js

@@ -64,8 +64,11 @@ export class SecretStorage {
             throw new Error("Bad MAC");
         }
 
-        const plaintextBytes = await this._cryptoDriver.aes.decrypt(
+        const plaintextBytes = await this._cryptoDriver.aes.decryptCTR({
-            aesKey, base64.decode(encryptedData.iv), ciphertextBytes);
+            key: aesKey,
+            iv: base64.decode(encryptedData.iv),
+            data: ciphertextBytes
+        });
 
         return textDecoder.decode(plaintextBytes);
     }

src/ui/web/dom/CryptoDriver.js

@@ -158,22 +158,26 @@ class CryptoAESDriver {
     }
     /**
      * [decrypt description]
-     * @param  {BufferSource} key        [description]
+     * @param  {string} keyFormat        "raw" or "jwk"
+     * @param  {BufferSource | Object} key        [description]
      * @param  {BufferSource} iv         [description]
-     * @param  {BufferSource} ciphertext [description]
+     * @param  {BufferSource} data [description]
+     * @param  {Number}       counterLength the size of the counter, in bits
      * @return {BufferSource}            [description]
      */
-    async decrypt(key, iv, ciphertext) {
+    async decryptCTR({key, jwkKey, iv, data, counterLength = 64}) {
         const opts = {
             name: "AES-CTR",
             counter: iv,
-            length: 64,
+            length: counterLength,
         };
         let aesKey;
         try {
+            const selectedKey = key || jwkKey;
+            const format = jwkKey ? "jwk" : "raw";
             aesKey = await subtleCryptoResult(this._subtleCrypto.importKey(
-                'raw',
+                format,
-                key,
+                selectedKey,
                 opts,
                 false,
                 ['decrypt'],
@@ -186,7 +190,7 @@ class CryptoAESDriver {
                 // see https://developer.mozilla.org/en-US/docs/Web/API/AesCtrParams
                 opts,
                 aesKey,
-                ciphertext,
+                data,
             ), "decrypt");
             return new Uint8Array(plaintext);
         } catch (err) {
@@ -205,12 +209,24 @@ class CryptoLegacyAESDriver {
      * @param  {BufferSource} key        [description]
      * @param  {BufferSource} iv         [description]
      * @param  {BufferSource} ciphertext [description]
+     * @param  {Number}       counterLength the size of the counter, in bits
      * @return {BufferSource}            [description]
      */
-    async decrypt(key, iv, ciphertext) {
+    async decryptCTR({key, jwkKey, iv, data, counterLength = 64}) {
+        // TODO: support counterLength and jwkKey
         const aesjs = this._aesjs;
+        // This won't work as aesjs throws with iv.length !== 16
+        // const nonceLength = 8;
+        // const expectedIVLength = (counterLength / 8) + nonceLength;
+        // if (iv.length < expectedIVLength) {
+        //     const newIV = new Uint8Array(expectedIVLength);
+        //     for(let i = 0; i < iv.length; ++i) {
+        //         newIV[i] = iv[i];
+        //     }
+        //     iv = newIV;
+        // }
         var aesCtr = new aesjs.ModeOfOperation.ctr(new Uint8Array(key), new aesjs.Counter(new Uint8Array(iv)));
-        return aesCtr.decrypt(new Uint8Array(ciphertext));
+        return aesCtr.decrypt(new Uint8Array(data));
     }
 }
 

src/ui/web/session/room/timeline/ImageView.js

@@ -23,14 +23,14 @@ export class ImageView extends TemplateView {
         const heightRatioPercent = (vm.thumbnailHeight / vm.thumbnailWidth) * 100;
         const image = t.img({
             className: "picture",
-            src: vm.thumbnailUrl,
+            src: vm => vm.thumbnailUrl,
             width: vm.thumbnailWidth,
             height: vm.thumbnailHeight,
             loading: "lazy",
             alt: vm.label,
         });
         const linkContainer = t.a({
-            href: vm.url,
+            href: vm => vm.url,
             target: "_blank",
             style: `padding-top: ${heightRatioPercent}%; width: ${vm.thumbnailWidth}px;`
         }, image);