imagify / vendor / wp-media / mcp-oauth / inc / Auth / JWT.php

JWT.php in Imagify Image Optimization: Optimize Images | Compress & Convert to WebP/AVIF 2.3.2, at vendor/wp-media/mcp-oauth/inc/Auth/JWT.php

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1	<?php
2	/**
3	* JWT Helper — pure HS256 implementation with no external dependencies.
4	*/
5
6	declare(strict_types=1);
7
8	namespace WPMedia\MCP\OAuth\Auth;
9
10	/**
11	* JWT encoder / decoder.
12	*
13	* Implements HS256 (HMAC-SHA256) signing. All methods are static so callers
14	* never need to instantiate the class.
15	*/
16	class JWT {
17
18	/**
19	* Encode a payload as a signed JWT.
20	*
21	* @param array<string, mixed> $payload Claims to include in the token.
22	* @param string $secret HMAC signing secret.
23	* @return string Signed JWT string.
24	*/
25	public static function encode( array $payload, string $secret ): string {
26	$header = self::base64url_encode(
27	(string) wp_json_encode(
28	[
29	'typ' => 'JWT',
30	'alg' => 'HS256',
31	]
32	)
33	);
34	$body = self::base64url_encode( (string) wp_json_encode( $payload ) );
35	$sig = self::base64url_encode( hash_hmac( 'sha256', $header . '.' . $body, $secret, true ) );
36
37	return $header . '.' . $body . '.' . $sig;
38	}
39
40	/**
41	* Decode and verify a JWT.
42	*
43	* Returns null if the signature is invalid or (when $verify_expiry is true)
44	* the token has expired. Pass false for $verify_expiry when the caller
45	* needs to act on an expired token — e.g. the revocation endpoint, which
46	* must accept expired tokens per RFC 7009.
47	*
48	* @param string $token JWT string.
49	* @param string $secret HMAC signing secret.
50	* @param bool $verify_expiry Whether to reject tokens whose exp has passed.
51	* @return array<string, mixed>\|null Decoded payload, or null on failure.
52	*/
53	public static function decode( string $token, string $secret, bool $verify_expiry = true ): ?array {
54	$parts = explode( '.', $token );
55	if ( 3 !== count( $parts ) ) {
56	return null;
57	}
58
59	list( $header, $body, $signature ) = $parts;
60
61	// Pin the algorithm. We only ever issue and verify HS256; rejecting any
62	// other alg (notably 'none') defends against algorithm-substitution
63	// attacks explicitly rather than relying on the HMAC comparison alone.
64	$header_data = json_decode( self::base64url_decode( $header ), true );
65	if ( ! is_array( $header_data ) \|\| 'HS256' !== ( $header_data['alg'] ?? '' ) ) {
66	return null;
67	}
68
69	$expected_sig = self::base64url_encode( hash_hmac( 'sha256', $header . '.' . $body, $secret, true ) );
70	if ( ! hash_equals( $expected_sig, $signature ) ) {
71	return null;
72	}
73
74	$payload = json_decode( self::base64url_decode( $body ), true );
75	if ( ! is_array( $payload ) ) {
76	return null;
77	}
78
79	if ( $verify_expiry && isset( $payload['exp'] ) && (int) $payload['exp'] < time() ) {
80	return null;
81	}
82
83	return $payload;
84	}
85
86	/**
87	* Base64URL-encode a binary string.
88	*
89	* @param string $data Raw bytes to encode.
90	* @return string URL-safe base64 without padding.
91	*/
92	public static function base64url_encode( string $data ): string {
93	return rtrim( strtr( base64_encode( $data ), '+/', '-_' ), '=' ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode
94	}
95
96	/**
97	* Base64URL-decode a string.
98	*
99	* @param string $data URL-safe base64 string.
100	* @return string Decoded binary string.
101	*/
102	private static function base64url_decode( string $data ): string {
103	return (string) base64_decode( strtr( $data, '-_', '+/' ) ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_decode
104	}
105	}
106