thinkrank / includes / core / class-secret-at-rest.php

class-secret-at-rest.php in ThinkRank AI SEO – AI SEO Plugin for WordPress: Schema, XML Sitemaps, Meta Tags, Search Console & Local SEO 2.4.0, at includes/core/class-secret-at-rest.php

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1	<?php
2	/**
3	* Encrypt-at-rest for plugin secrets.
4	*
5	* The scheme Settings has used for API keys and OAuth tokens since 1.20 —
6	* libsodium `secretbox` under a key derived from the site's auth salt, marked
7	* by a `trenc:v1:` prefix — lifted out so anything else holding a credential
8	* can use it. Settings delegates here, so a value written by one reads back
9	* through the other.
10	*
11	* This protects a leaked database dump: a backup, a shared-host read, another
12	* plugin's SQL injection. It does not protect a leaked server, because the key
13	* comes from wp-config.php.
14	*
15	* @package ThinkRank
16	* @subpackage Core
17	* @since 2.0.1
18	*/
19
20	declare(strict_types=1);
21
22	namespace ThinkRank\Core;
23
24	// Prevent direct access
25	if (!defined('ABSPATH')) {
26	exit;
27	}
28
29	/**
30	* Encrypt-at-rest helper.
31	*
32	* @since 2.0.1
33	*/
34	class Secret_At_Rest {
35
36	/**
37	* Marks a value as encrypted by this class.
38	*
39	* @var string
40	*/
41	public const PREFIX = 'trenc:v1:';
42
43	/**
44	* Encrypt a secret for storage.
45	*
46	* Falls back to the plaintext value where sodium is unavailable or no salt
47	* can be derived, so behaviour stays stable on a host that cannot encrypt
48	* rather than silently storing nothing.
49	*
50	* @since 2.0.1
51	*
52	* @param string $value Raw secret.
53	* @return string Ciphertext envelope, or the value unchanged.
54	*/
55	public static function encrypt(string $value): string {
56	if ('' === $value \|\| !function_exists('sodium_crypto_secretbox')) {
57	return $value;
58	}
59
60	$key = self::key();
61
62	if ('' === $key) {
63	return $value;
64	}
65
66	try {
67	$nonce = random_bytes(SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
68	$cipher = sodium_crypto_secretbox($value, $nonce, $key);
69
70	// phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode -- transport encoding for a sodium ciphertext, not obfuscation.
71	return self::PREFIX . base64_encode($nonce . $cipher);
72	} catch (\Exception $e) {
73	return $value;
74	}
75	}
76
77	/**
78	* Decrypt a value written by encrypt().
79	*
80	* A value without the marker is legacy plaintext and returned untouched.
81	* A value that carries the marker and will not open is unrecoverable — the
82	* auth salt changed, or the row is corrupt — and returns '' rather than the
83	* ciphertext, which would otherwise be sent upstream as a credential and
84	* produce an opaque 401 far from the cause.
85	*
86	* @since 2.0.1
87	*
88	* @param string $value Stored value.
89	* @return string Plaintext, the original value, or ''.
90	*/
91	public static function decrypt(string $value): string {
92	if (0 !== strncmp($value, self::PREFIX, strlen(self::PREFIX))) {
93	return $value;
94	}
95
96	if (!function_exists('sodium_crypto_secretbox_open')) {
97	return $value;
98	}
99
100	$key = self::key();
101
102	if ('' === $key) {
103	return $value;
104	}
105
106	// phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_decode -- decodes our own ciphertext envelope; strict mode is on.
107	$decoded = base64_decode(substr($value, strlen(self::PREFIX)), true);
108
109	if (false === $decoded \|\| strlen($decoded) <= SODIUM_CRYPTO_SECRETBOX_NONCEBYTES) {
110	return $value;
111	}
112
113	$nonce = substr($decoded, 0, SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
114	$cipher = substr($decoded, SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
115	$plain = sodium_crypto_secretbox_open($cipher, $nonce, $key);
116
117	return false === $plain ? '' : $plain;
118	}
119
120	/**
121	* Whether a stored value is one of ours.
122	*
123	* @since 2.0.1
124	*
125	* @param string $value Stored value.
126	* @return bool
127	*/
128	public static function is_encrypted(string $value): bool {
129	return 0 === strncmp($value, self::PREFIX, strlen(self::PREFIX));
130	}
131
132	/**
133	* Derive the 32-byte key from the site's auth salt.
134	*
135	* @since 2.0.1
136	*
137	* @return string Raw 32-byte key, or '' when salts are unavailable.
138	*/
139	private static function key(): string {
140	if (!function_exists('wp_salt')) {
141	return '';
142	}
143
144	// SHA-256 output length matches SODIUM_CRYPTO_SECRETBOX_KEYBYTES.
145	// The literal is the one Settings has always used, so values written
146	// before this class existed still open.
147	return hash('sha256', 'thinkrank-settings\|' . wp_salt('auth'), true);
148	}
149	}
150