Import external bcrypt plugin for password hashing

It was noted in <#216> that
our project template defaults to WordPress default hashing method for
password, which is still in 2024 weak MD5. There has for a long time
existed mu-plugin, which can be used to replace password hashing with
bcrypt.

This plugin hooks to WordPress core password handling functions, and
overrides password checks so all obsolete MD5-hashed passwords will be
converted to bcrypt (or whatever is in future the PHP default password
hashing function).

See source code for more documentation.

Source:
<https://raw.githubusercontent.com/roots/wp-password-bcrypt/master/wp-password-bcrypt.php>
Original commit: <15f0d8919fb3731f79a0cf2fb47e1baecb86cb26>
License: MIT
Author: Roots
Author URI: <https://roots.io>

Closes: #216

.gitignore

@@ -25,6 +25,7 @@ htdocs/wp-content/mu-plugins/*
 !htdocs/wp-content/mu-plugins/.gitkeep
 !htdocs/wp-content/mu-plugins/register-theme-directory.php
 !htdocs/wp-content/mu-plugins/bedrock-autoloader.php
+!htdocs/wp-content/mu-plugins/wp-password-bcrypt.php
 htdocs/wp-content/themes/twenty*
 !htdocs/wp-content/themes/.gitkeep
 htdocs/wp-content/languages/*

htdocs/wp-content/mu-plugins/wp-password-bcrypt.php

@@ -0,0 +1,137 @@
+<?php
+
+/**
+ * Plugin Name: WP Password bcrypt
+ * Plugin URI:  https://github.com/roots/wp-password-bcrypt
+ * Description: Replaces wp_hash_password and wp_check_password with password_hash and password_verify.
+ * Author:      Roots
+ * Author URI:  https://roots.io
+ * Version:     1.1.0
+ * Licence:     MIT
+ */
+
+/**
+ * Determine if the plaintext password matches the encrypted password hash.
+ *
+ * If the password hash is not encrypted using the PASSWORD_DEFAULT (bcrypt)
+ * algorithm, the password will be rehashed and updated once verified.
+ *
+ * @link https://www.php.net/manual/en/function.password-verify.php
+ * @link https://www.php.net/manual/en/function.password-needs-rehash.php
+ *
+ * @param  string     $password The password in plaintext.
+ * @param  string     $hash     The hashed password to check against.
+ * @param  string|int $user_id  The optional user ID.
+ * @return bool
+ *
+ * @SuppressWarnings(PHPMD.CamelCaseVariableName) $wp_hasher
+ */
+function wp_check_password($password, $hash, $user_id = '')
+{
+    if (! password_needs_rehash($hash, PASSWORD_DEFAULT, apply_filters('wp_hash_password_options', []))) {
+        return apply_filters(
+            'check_password',
+            password_verify($password, $hash),
+            $password,
+            $hash,
+            $user_id
+        );
+    }
+
+    global $wp_hasher;
+
+    if (empty($wp_hasher)) {
+        require_once ABSPATH . WPINC . '/class-phpass.php';
+        $wp_hasher = new PasswordHash(8, true);
+    }
+
+    if (! empty($user_id) && $wp_hasher->CheckPassword($password, $hash)) {
+        $hash = wp_set_password($password, $user_id);
+    }
+
+    return apply_filters(
+        'check_password',
+        password_verify($password, $hash),
+        $password,
+        $hash,
+        $user_id
+    );
+}
+
+/**
+ * Hash the provided password using the PASSWORD_DEFAULT (bcrypt)
+ * algorithm.
+ *
+ * @link https://www.php.net/manual/en/function.password-hash.php
+ *
+ * @param  string $password The password in plain text.
+ * @return string
+ */
+function wp_hash_password($password)
+{
+    return password_hash(
+        $password,
+        PASSWORD_DEFAULT,
+        apply_filters('wp_hash_password_options', [])
+    );
+}
+
+/**
+ * Hash and update the user's password.
+ *
+ * @param  string $password The new user password in plaintext.
+ * @param  int    $user_id  The user ID.
+ * @return string
+ */
+function wp_set_password($password, $user_id)
+{
+    $hash = wp_hash_password($password);
+    $is_api_request = apply_filters(
+        'application_password_is_api_request',
+        (defined('XMLRPC_REQUEST') && XMLRPC_REQUEST) ||
+        (defined('REST_REQUEST') && REST_REQUEST)
+    );
+
+    if (! $is_api_request) {
+        global $wpdb;
+
+        $wpdb->update($wpdb->users, [
+            'user_pass' => $hash,
+            'user_activation_key' => ''
+        ], ['ID' => $user_id]);
+
+        clean_user_cache($user_id);
+
+        return $hash;
+    }
+
+    if (
+        ! class_exists('WP_Application_Passwords') ||
+        empty($passwords = WP_Application_Passwords::get_user_application_passwords($user_id))
+    ) {
+        return;
+    }
+
+    global $wp_hasher;
+
+    if (empty($wp_hasher)) {
+        require_once ABSPATH . WPINC . '/class-phpass.php';
+        $wp_hasher = new PasswordHash(8, true);
+    }
+
+    foreach ($passwords as $key => $value) {
+        if (! $wp_hasher->CheckPassword($password, $value['password'])) {
+            continue;
+        }
+
+        $passwords[$key]['password'] = $hash;
+    }
+
+    update_user_meta(
+        $user_id,
+        WP_Application_Passwords::USERMETA_KEY_APPLICATION_PASSWORDS,
+        $passwords
+    );
+
+    return $hash;
+}