Use PBKDF for pwd-box

src/boxes/pwd.ts

@@ -1,6 +1,7 @@
 import {Result} from 'result'
 import * as misc from 'misc'
 import {SecretBox} from './symmetric'
+import {pbkdf} from '../pbkdf'
 
 export class PwdBox<T> {
     private readonly secret_box: SecretBox<T>
@@ -25,26 +26,7 @@ export class PwdBox<T> {
     }
 
     private static async gen_key(pwd: string, salt: Uint8Array) : Promise<CryptoKey> {
-        const keyMaterial = await window.crypto.subtle.importKey(
-            "raw",
-            new TextEncoder().encode(pwd),
-            "PBKDF2",
-            false,
-            ["deriveBits", "deriveKey"],
-        )
-
-        return crypto.subtle.deriveKey(
-            {
-                name: "PBKDF2",
-                iterations: 250_000,
-                hash: "SHA-512",
-                salt,
-            },
-            keyMaterial,
-            {name: "AES-GCM", length: 256},
-            false,
-            ["encrypt", "decrypt"],
-        )
+        return pbkdf(pwd, salt, ["encrypt", "decrypt"])
     }
 
     public toString() : string {