learnpress / inc / jwt / includes / php-jwt / JWT.php

JWT.php in LearnPress – WordPress LMS Plugin for Create and Sell Online Courses 4.2.1, at inc/jwt/includes/php-jwt/JWT.php

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1	<?php
2
3	namespace Firebase\JWT;
4	use \DomainException;
5	use \InvalidArgumentException;
6	use \UnexpectedValueException;
7	use \DateTime;
8
9	/**
10	* JSON Web Token implementation, based on this spec:
11	* https://tools.ietf.org/html/rfc7519
12	*
13	* PHP version 5
14	*
15	* @category Authentication
16	* @package Authentication_JWT
17	* @author Neuman Vong <neuman@twilio.com>
18	* @author Anant Narayanan <anant@php.net>
19	* @license http://opensource.org/licenses/BSD-3-Clause 3-clause BSD
20	* @link https://github.com/firebase/php-jwt
21	*/
22	class JWT {
23
24
25	/**
26	* When checking nbf, iat or expiration times,
27	* we want to provide some extra leeway time to
28	* account for clock skew.
29	*/
30	public static $leeway = 0;
31
32	/**
33	* Allow the current timestamp to be specified.
34	* Useful for fixing a value within unit testing.
35	*
36	* Will default to PHP time() value if null.
37	*/
38	public static $timestamp = null;
39
40	public static $supported_algs = array(
41	'HS256' => array( 'hash_hmac', 'SHA256' ),
42	'HS512' => array( 'hash_hmac', 'SHA512' ),
43	'HS384' => array( 'hash_hmac', 'SHA384' ),
44	'RS256' => array( 'openssl', 'SHA256' ),
45	'RS384' => array( 'openssl', 'SHA384' ),
46	'RS512' => array( 'openssl', 'SHA512' ),
47	);
48
49	/**
50	* Decodes a JWT string into a PHP object.
51	*
52	* @param string $jwt The JWT
53	* @param string\|array $key The key, or map of keys.
54	* If the algorithm used is asymmetric, this is the public key
55	* @param array $allowed_algs List of supported verification algorithms
56	* Supported algorithms are 'HS256', 'HS384', 'HS512' and 'RS256'
57	*
58	* @return object The JWT's payload as a PHP object
59	*
60	* @throws UnexpectedValueException Provided JWT was invalid
61	* @throws SignatureInvalidException Provided JWT was invalid because the signature verification failed
62	* @throws BeforeValidException Provided JWT is trying to be used before it's eligible as defined by 'nbf'
63	* @throws BeforeValidException Provided JWT is trying to be used before it's been created as defined by 'iat'
64	* @throws ExpiredException Provided JWT has since expired, as defined by the 'exp' claim
65	*
66	* @uses jsonDecode
67	* @uses urlsafeB64Decode
68	*/
69	public static function decode( $jwt, $key, array $allowed_algs = array() ) {
70	$timestamp = is_null( static::$timestamp ) ? time() : static::$timestamp;
71
72	if ( empty( $key ) ) {
73	throw new InvalidArgumentException( 'Key may not be empty' );
74	}
75	$tks = explode( '.', $jwt );
76	if ( count( $tks ) != 3 ) {
77	throw new UnexpectedValueException( 'Wrong number of segments' );
78	}
79	list($headb64, $bodyb64, $cryptob64) = $tks;
80	if ( null === ( $header = static::jsonDecode( static::urlsafeB64Decode( $headb64 ) ) ) ) {
81	throw new UnexpectedValueException( 'Invalid header encoding' );
82	}
83	if ( null === $payload = static::jsonDecode( static::urlsafeB64Decode( $bodyb64 ) ) ) {
84	throw new UnexpectedValueException( 'Invalid claims encoding' );
85	}
86	if ( false === ( $sig = static::urlsafeB64Decode( $cryptob64 ) ) ) {
87	throw new UnexpectedValueException( 'Invalid signature encoding' );
88	}
89	if ( empty( $header->alg ) ) {
90	throw new UnexpectedValueException( 'Empty algorithm' );
91	}
92	if ( empty( static::$supported_algs[ $header->alg ] ) ) {
93	throw new UnexpectedValueException( 'Algorithm not supported' );
94	}
95	if ( ! in_array( $header->alg, $allowed_algs ) ) {
96	throw new UnexpectedValueException( 'Algorithm not allowed' );
97	}
98	if ( is_array( $key ) \|\| $key instanceof \ArrayAccess ) {
99	if ( isset( $header->kid ) ) {
100	if ( ! isset( $key[ $header->kid ] ) ) {
101	throw new UnexpectedValueException( '"kid" invalid, unable to lookup correct key' );
102	}
103	$key = $key[ $header->kid ];
104	} else {
105	throw new UnexpectedValueException( '"kid" empty, unable to lookup correct key' );
106	}
107	}
108
109	// Check the signature
110	if ( ! static::verify( "$headb64.$bodyb64", $sig, $key, $header->alg ) ) {
111	throw new SignatureInvalidException( 'Signature verification failed' );
112	}
113
114	// Check if the nbf if it is defined. This is the time that the
115	// token can actually be used. If it's not yet that time, abort.
116	if ( isset( $payload->nbf ) && $payload->nbf > ( $timestamp + static::$leeway ) ) {
117	throw new BeforeValidException(
118	'Cannot handle token prior to ' . date( DateTime::ISO8601, $payload->nbf )
119	);
120	}
121
122	// Check that this token has been created before 'now'. This prevents
123	// using tokens that have been created for later use (and haven't
124	// correctly used the nbf claim).
125	if ( isset( $payload->iat ) && $payload->iat > ( $timestamp + static::$leeway ) ) {
126	throw new BeforeValidException(
127	'Cannot handle token prior to ' . date( DateTime::ISO8601, $payload->iat )
128	);
129	}
130
131	// Check if this token has expired.
132	if ( isset( $payload->exp ) && ( $timestamp - static::$leeway ) >= $payload->exp ) {
133	throw new ExpiredException( 'Expired token' );
134	}
135
136	return $payload;
137	}
138
139	/**
140	* Converts and signs a PHP object or array into a JWT string.
141	*
142	* @param object\|array $payload PHP object or array
143	* @param string $key The secret key.
144	* If the algorithm used is asymmetric, this is the private key
145	* @param string $alg The signing algorithm.
146	* Supported algorithms are 'HS256', 'HS384', 'HS512' and 'RS256'
147	* @param mixed $keyId
148	* @param array $head An array with header elements to attach
149	*
150	* @return string A signed JWT
151	*
152	* @uses jsonEncode
153	* @uses urlsafeB64Encode
154	*/
155	public static function encode( $payload, $key, $alg = 'HS256', $keyId = null, $head = null ) {
156	$header = array(
157	'typ' => 'JWT',
158	'alg' => $alg,
159	);
160	if ( $keyId !== null ) {
161	$header['kid'] = $keyId;
162	}
163	if ( isset( $head ) && is_array( $head ) ) {
164	$header = array_merge( $head, $header );
165	}
166	$segments = array();
167	$segments[] = static::urlsafeB64Encode( static::jsonEncode( $header ) );
168	$segments[] = static::urlsafeB64Encode( static::jsonEncode( $payload ) );
169	$signing_input = implode( '.', $segments );
170
171	$signature = static::sign( $signing_input, $key, $alg );
172	$segments[] = static::urlsafeB64Encode( $signature );
173
174	return implode( '.', $segments );
175	}
176
177	/**
178	* Sign a string with a given key and algorithm.
179	*
180	* @param string $msg The message to sign
181	* @param string\|resource $key The secret key
182	* @param string $alg The signing algorithm.
183	* Supported algorithms are 'HS256', 'HS384', 'HS512' and 'RS256'
184	*
185	* @return string An encrypted message
186	*
187	* @throws DomainException Unsupported algorithm was specified
188	*/
189	public static function sign( $msg, $key, $alg = 'HS256' ) {
190	if ( empty( static::$supported_algs[ $alg ] ) ) {
191	throw new DomainException( 'Algorithm not supported' );
192	}
193	list($function, $algorithm) = static::$supported_algs[ $alg ];
194	switch ( $function ) {
195	case 'hash_hmac':
196	return hash_hmac( $algorithm, $msg, $key, true );
197	case 'openssl':
198	$signature = '';
199	$success = openssl_sign( $msg, $signature, $key, $algorithm );
200	if ( ! $success ) {
201	throw new DomainException( 'OpenSSL unable to sign data' );
202	} else {
203	return $signature;
204	}
205	}
206	}
207
208	/**
209	* Verify a signature with the message, key and method. Not all methods
210	* are symmetric, so we must have a separate verify and sign method.
211	*
212	* @param string $msg The original message (header and body)
213	* @param string $signature The original signature
214	* @param string\|resource $key For HS, a string key works. for RS, must be a resource of an openssl public key
215	* @param string $alg The algorithm
216	*
217	* @return bool
218	*
219	* @throws DomainException Invalid Algorithm or OpenSSL failure
220	*/
221	private static function verify( $msg, $signature, $key, $alg ) {
222	if ( empty( static::$supported_algs[ $alg ] ) ) {
223	throw new DomainException( 'Algorithm not supported' );
224	}
225
226	list($function, $algorithm) = static::$supported_algs[ $alg ];
227	switch ( $function ) {
228	case 'openssl':
229	$success = openssl_verify( $msg, $signature, $key, $algorithm );
230	if ( $success === 1 ) {
231	return true;
232	} elseif ( $success === 0 ) {
233	return false;
234	}
235	// returns 1 on success, 0 on failure, -1 on error.
236	throw new DomainException(
237	'OpenSSL error: ' . openssl_error_string()
238	);
239	case 'hash_hmac':
240	default:
241	$hash = hash_hmac( $algorithm, $msg, $key, true );
242	if ( function_exists( 'hash_equals' ) ) {
243	return hash_equals( $signature, $hash );
244	}
245	$len = min( static::safeStrlen( $signature ), static::safeStrlen( $hash ) );
246
247	$status = 0;
248	for ( $i = 0; $i < $len; $i++ ) {
249	$status \|= ( ord( $signature[ $i ] ) ^ ord( $hash[ $i ] ) );
250	}
251	$status \|= ( static::safeStrlen( $signature ) ^ static::safeStrlen( $hash ) );
252
253	return ( $status === 0 );
254	}
255	}
256
257	/**
258	* Decode a JSON string into a PHP object.
259	*
260	* @param string $input JSON string
261	*
262	* @return object Object representation of JSON string
263	*
264	* @throws DomainException Provided string was invalid JSON
265	*/
266	public static function jsonDecode( $input ) {
267	if ( version_compare( PHP_VERSION, '5.4.0', '>=' ) && ! ( defined( 'JSON_C_VERSION' ) && PHP_INT_SIZE > 4 ) ) {
268	/** In PHP >=5.4.0, json_decode() accepts an options parameter, that allows you
269	* to specify that large ints (like Steam Transaction IDs) should be treated as
270	* strings, rather than the PHP default behaviour of converting them to floats.
271	*/
272	$obj = json_decode( $input, false, 512, JSON_BIGINT_AS_STRING );
273	} else {
274	/** Not all servers will support that, however, so for older versions we must
275	* manually detect large ints in the JSON string and quote them (thus converting
276	*them to strings) before decoding, hence the preg_replace() call.
277	*/
278	$max_int_length = strlen( (string) PHP_INT_MAX ) - 1;
279	$json_without_bigints = preg_replace( '/:\s*(-?\d{' . $max_int_length . ',})/', ': "$1"', $input );
280	$obj = json_decode( $json_without_bigints );
281	}
282
283	if ( function_exists( 'json_last_error' ) && $errno = json_last_error() ) {
284	static::handleJsonError( $errno );
285	} elseif ( $obj === null && $input !== 'null' ) {
286	throw new DomainException( 'Null result with non-null input' );
287	}
288	return $obj;
289	}
290
291	/**
292	* Encode a PHP object into a JSON string.
293	*
294	* @param object\|array $input A PHP object or array
295	*
296	* @return string JSON representation of the PHP object or array
297	*
298	* @throws DomainException Provided object could not be encoded to valid JSON
299	*/
300	public static function jsonEncode( $input ) {
301	$json = json_encode( $input );
302	if ( function_exists( 'json_last_error' ) && $errno = json_last_error() ) {
303	static::handleJsonError( $errno );
304	} elseif ( $json === 'null' && $input !== null ) {
305	throw new DomainException( 'Null result with non-null input' );
306	}
307	return $json;
308	}
309
310	/**
311	* Decode a string with URL-safe Base64.
312	*
313	* @param string $input A Base64 encoded string
314	*
315	* @return string A decoded string
316	*/
317	public static function urlsafeB64Decode( $input ) {
318	$remainder = strlen( $input ) % 4;
319	if ( $remainder ) {
320	$padlen = 4 - $remainder;
321	$input .= str_repeat( '=', $padlen );
322	}
323	return base64_decode( strtr( $input, '-_', '+/' ) );
324	}
325
326	/**
327	* Encode a string with URL-safe Base64.
328	*
329	* @param string $input The string you want encoded
330	*
331	* @return string The base64 encode of what you passed in
332	*/
333	public static function urlsafeB64Encode( $input ) {
334	return str_replace( '=', '', strtr( base64_encode( $input ), '+/', '-_' ) );
335	}
336
337	/**
338	* Helper method to create a JSON error.
339	*
340	* @param int $errno An error number from json_last_error()
341	*
342	* @return void
343	*/
344	private static function handleJsonError( $errno ) {
345	$messages = array(
346	JSON_ERROR_DEPTH => 'Maximum stack depth exceeded',
347	JSON_ERROR_STATE_MISMATCH => 'Invalid or malformed JSON',
348	JSON_ERROR_CTRL_CHAR => 'Unexpected control character found',
349	JSON_ERROR_SYNTAX => 'Syntax error, malformed JSON',
350	JSON_ERROR_UTF8 => 'Malformed UTF-8 characters', //PHP >= 5.3.3
351	);
352	throw new DomainException(
353	isset( $messages[ $errno ] )
354	? $messages[ $errno ]
355	: 'Unknown JSON error: ' . $errno
356	);
357	}
358
359	/**
360	* Get the number of bytes in cryptographic strings.
361	*
362	* @param string
363	*
364	* @return int
365	*/
366	private static function safeStrlen( $str ) {
367	if ( function_exists( 'mb_strlen' ) ) {
368	return mb_strlen( $str, '8bit' );
369	}
370	return strlen( $str );
371	}
372	}
373