add loadWasm in pbkdf2 and update readme

Author: PeterAlfredLee

README-CN.md

@@ -39,8 +39,6 @@ yarn add @originjs/crypto-js-wasm
 
 在使用各算法前需调用一次对应的`loadWasm()`，或调用`loadAllWasm()`以加载所有算法的WebAssembly文件。
 
-
-
 ```javascript
 import CryptoJSW from 'crypto-js-wasm';
 
@@ -59,6 +57,10 @@ CryptoJSW.SHA256.loadWasm().then(() => {
 })
 ```
 
+需要注意的是，`HMAC` 没有`loadWasm`，因为如果要使用`HMAC`，必须指定哈希（例如`HmacSHA1`）。
+
+同时， `pbkdf2` 中的 `loadWasm` 实现是调用了 `SHA1.loadWasm` ，这是因为 `SHA1` 是 `pbkdf2` 的默认哈希算法。 如果指定了另一个哈希算法，则应分别调用该哈希算法对应的 `loadWasm`。 `evpkdf`/`MD5` 的情况与之类似， `MD5` 是 `evpkdf` 的默认哈希算法。
+
 
 
 **目前可用的算法**

README.md

@@ -39,8 +39,6 @@ yarn add @originjs/crypto-js-wasm
 
 Note that the async function `loadWasm()` should be called once (and once only!) for each algorithm that will be used, unless `loadAllWasm()` is called at the very beginning.
 
-
-
 ```javascript
 import CryptoJSW from 'crypto-js-wasm';
 
@@ -59,6 +57,10 @@ CryptoJSW.SHA256.loadWasm().then(() => {
 })
 ```
 
+Please note that `HMAC` does not have a `loadWasm`, as a hasher must be specified if you want to use `HMAC` (i.e. `HmacSHA1`).
+
+And the `loadWasm` in `pbkdf2` only calls `SHA1.loadWasm` as `SHA1` is the default hasher of `pbkdf2`. If you specified another hasher, the corresponding `loadWasm` of the hasher should be called repectly. Same case in `evpkdf`/`MD5` as `MD5` is the default hasher of `evpkdf`.
+
 
 
 **Available standards**

src/algo/pbkdf2/pbkdf2.js

@@ -42,6 +42,20 @@ export class PBKDF2Algo extends Base {
     );
   }
 
+  /**
+   * SHA1 is the default hasher of pbkdf2.
+   * With another hasher configured, user should call the corresponding loadWasm of the configured hasher.
+   *
+   * @returns {Promise<null>}
+   */
+  static async loadWasm() {
+    return SHA1Algo.loadWasm();
+  }
+
+  async loadWasm() {
+    return PBKDF2Algo.loadWasm();
+  }
+
   /**
    * Computes the Password-Based Key Derivation Function 2.
    *

test/hmac.sha224.test.js

@@ -1,7 +1,7 @@
 import C from '../src/index';
 
 beforeAll(async () => {
-  await C.SHA224.loadWasm();
+  await C.HmacSHA224.loadWasm();
 });
 
 describe('algo-hmac-sha224-test', () => {

test/hmac.sha256.test.js

@@ -1,7 +1,7 @@
 import C from '../src/index';
 
 beforeAll(async () => {
-  await C.SHA256.loadWasm();
+  await C.HmacSHA256.loadWasm();
 });
 
 describe('algo-hmac-sha256-test', () => {

test/hmac.sha384.test.js

@@ -1,7 +1,7 @@
 import C from '../src/index';
 
 beforeAll(async () => {
-  await C.SHA384.loadWasm();
+  await C.HmacSHA384.loadWasm();
 });
 
 describe('algo-hmac-sha384-test', () => {

test/hmac.sha512.test.js

@@ -1,7 +1,7 @@
 import C from '../src/index';
 
 beforeAll(async () => {
-  await C.SHA512.loadWasm();
+  await C.HmacSHA512.loadWasm();
 });
 
 describe('algo-hmac-sha512-test', () => {