move textencoder/decoder into platform

src/matrix/Session.js

@@ -184,7 +184,7 @@ export class Session {
         if (this._sessionBackup) {
             return false;
         }
-        const key = await ssssKeyFromCredential(type, credential, this._storage, this._platform.crypto, this._olm);
+        const key = await ssssKeyFromCredential(type, credential, this._storage, this._platform, this._olm);
         // and create session backup, which needs to read from accountData
         const readTxn = this._storage.readTxn([
             this._storage.storeNames.accountData,
@@ -206,7 +206,7 @@ export class Session {
     }
 
     async _createSessionBackup(ssssKey, txn) {
-        const secretStorage = new SecretStorage({key: ssssKey, crypto: this._platform.crypto});
+        const secretStorage = new SecretStorage({key: ssssKey, platform: this._platform});
         this._sessionBackup = await SessionBackup.fromSecretStorage({olm: this._olm, secretStorage, hsApi: this._hsApi, txn});
         if (this._sessionBackup) {
             for (const room of this._rooms.values()) {

src/matrix/ssss/SecretStorage.js

@@ -17,9 +17,9 @@ limitations under the License.
 import base64 from "../../../lib/base64-arraybuffer/index.js";
 
 export class SecretStorage {
-    constructor({key, crypto}) {
+    constructor({key, platform}) {
         this._key = key;
-        this._crypto = crypto;
+        this._platform = platform;
     }
 
     async readSecret(name, txn) {
@@ -40,14 +40,11 @@ export class SecretStorage {
     }
 
     async _decryptAESSecret(type, encryptedData) {
-        // TODO: we should we move this to platform specific code
-        const textEncoder = new TextEncoder();
-        const textDecoder = new TextDecoder();
         // now derive the aes and mac key from the 4s key
-        const hkdfKey = await this._crypto.derive.hkdf(
+        const hkdfKey = await this._platform.crypto.derive.hkdf(
             this._key.binaryKey,
             new Uint8Array(8).buffer,   //zero salt
-            textEncoder.encode(type), // info
+            this._platform.utf8.encode(type), // info
             "SHA-256",
             512 // 512 bits or 64 bytes
         );
@@ -56,7 +53,7 @@ export class SecretStorage {
 
         const ciphertextBytes = base64.decode(encryptedData.ciphertext);
 
-        const isVerified = await this._crypto.hmac.verify(
+        const isVerified = await this._platform.crypto.hmac.verify(
             hmacKey, base64.decode(encryptedData.mac),
             ciphertextBytes, "SHA-256");
 
@@ -64,12 +61,12 @@ export class SecretStorage {
             throw new Error("Bad MAC");
         }
 
-        const plaintextBytes = await this._crypto.aes.decryptCTR({
+        const plaintextBytes = await this._platform.crypto.aes.decryptCTR({
             key: aesKey,
             iv: base64.decode(encryptedData.iv),
             data: ciphertextBytes
         });
 
-        return textDecoder.decode(plaintextBytes);
+        return this._platform.utf8.decode(plaintextBytes);
     }
 }

src/matrix/ssss/index.js

@@ -47,14 +47,14 @@ export async function readKey(txn) {
     return new Key(new KeyDescription(keyData.id, keyAccountData), keyData.binaryKey);
 }
 
-export async function keyFromCredential(type, credential, storage, crypto, olm) {
+export async function keyFromCredential(type, credential, storage, platform, olm) {
     const keyDescription = await readDefaultKeyDescription(storage);
     if (!keyDescription) {
         throw new Error("Could not find a default secret storage key in account data");
     }
     let key;
     if (type === "phrase") {
-        key = await keyFromPassphrase(keyDescription, credential, crypto);
+        key = await keyFromPassphrase(keyDescription, credential, platform);
     } else if (type === "key") {
         key = keyFromRecoveryKey(olm, keyDescription, credential);
     } else {

src/matrix/ssss/passphrase.js

@@ -22,10 +22,10 @@ const DEFAULT_BITSIZE = 256;
 /**
  * @param  {KeyDescription} keyDescription
  * @param  {string} passphrase
- * @param  {Crypto} crypto
+ * @param  {Platform} platform
  * @return {Key}
  */
-export async function keyFromPassphrase(keyDescription, passphrase, crypto) {
+export async function keyFromPassphrase(keyDescription, passphrase, platform) {
     const {passphraseParams} = keyDescription;
     if (!passphraseParams) {
         throw new Error("not a passphrase key");
@@ -33,13 +33,11 @@ export async function keyFromPassphrase(keyDescription, passphrase, crypto) {
     if (passphraseParams.algorithm !== "m.pbkdf2") {
         throw new Error(`Unsupported passphrase algorithm: ${passphraseParams.algorithm}`);
     }
-    // TODO: we should we move this to platform specific code
-    const textEncoder = new TextEncoder();
-    const keyBits = await crypto.derive.pbkdf2(
-        textEncoder.encode(passphrase),
+    const keyBits = await platform.crypto.derive.pbkdf2(
+        platform.utf8.encode(passphrase),
         passphraseParams.iterations || DEFAULT_ITERATIONS,
         // salt is just a random string, not encoded in any way
-        textEncoder.encode(passphraseParams.salt),
+        platform.utf8.encode(passphraseParams.salt),
         "SHA-512",
         passphraseParams.bits || DEFAULT_BITSIZE);
     return new Key(keyDescription, keyBits);

src/platform/web/Platform.js

@@ -19,6 +19,7 @@ import {xhrRequest} from "./dom/request/xhr.js";
 import {StorageFactory} from "../../matrix/storage/idb/StorageFactory.js";
 import {SessionInfoStorage} from "../../matrix/sessioninfo/localstorage/SessionInfoStorage.js";
 import {SettingsStorage} from "./dom/SettingsStorage.js";
+import {UTF8} from "./dom/UTF8.js";
 import {OlmWorker} from "../../matrix/e2ee/OlmWorker.js";
 import {RootView} from "./ui/RootView.js";
 import {Clock} from "./dom/Clock.js";
@@ -83,6 +84,7 @@ export class Platform {
     constructor(container, paths, cryptoExtras = null) {
         this._paths = paths;
         this._container = container;
+        this.utf8 = new UTF8();
         this.clock = new Clock();
         this.history = new History();
         this.onlineStatus = new OnlineStatus();

src/platform/web/dom/UTF8.js

@@ -0,0 +1,35 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+export class UTF8 {
+    constructor() {
+        this._encoder = null;
+        this._decoder = null;
+    }
+
+    encode(str) {
+        if (!this._encoder) {
+            this._encoder = new TextEncoder();
+        }
+        return this._encoder.encode(str);
+    }
+
+    decode(buffer) {
+        if (!this._decoder) {
+            this._decoder = new TextDecoder();
+        }
+        return this._decoder.decode(buffer);
+    }
+}