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<?php
namespace Firebase\JWT;
use ArrayAccess;
use DateTime;
use DomainException;
use Exception;
use InvalidArgumentException;
use OpenSSLAsymmetricKey;
use OpenSSLCertificate;
use stdClass;
use UnexpectedValueException;
/**
* JSON Web Token implementation, based on this spec:
* https://tools.ietf.org/html/rfc7519
*
* PHP version 5
*
* @category Authentication
* @package Authentication_JWT
* @author Neuman Vong <neuman@twilio.com>
* @author Anant Narayanan <anant@php.net>
* @license http://opensource.org/licenses/BSD-3-Clause 3-clause BSD
* @link https://github.com/firebase/php-jwt
*/
class JWT
{
private const ASN1_INTEGER = 0x02;
private const ASN1_SEQUENCE = 0x10;
private const ASN1_BIT_STRING = 0x03;
/**
* When checking nbf, iat or expiration times,
* we want to provide some extra leeway time to
* account for clock skew.
*
* @var int
*/
public static $leeway = 0;
/**
* Allow the current timestamp to be specified.
* Useful for fixing a value within unit testing.
* Will default to PHP time() value if null.
*
* @var ?int
*/
public static $timestamp = null;
/**
* @var array<string, string[]>
*/
public static $supported_algs = [
'ES384' => ['openssl', 'SHA384'],
'ES256' => ['openssl', 'SHA256'],
'ES256K' => ['openssl', 'SHA256'],
'HS256' => ['hash_hmac', 'SHA256'],
'HS384' => ['hash_hmac', 'SHA384'],
'HS512' => ['hash_hmac', 'SHA512'],
'RS256' => ['openssl', 'SHA256'],
'RS384' => ['openssl', 'SHA384'],
'RS512' => ['openssl', 'SHA512'],
'EdDSA' => ['sodium_crypto', 'EdDSA'],
];
/**
* Decodes a JWT string into a PHP object.
*
* @param string $jwt The JWT
* @param Key|ArrayAccess<string,Key>|array<string,Key> $keyOrKeyArray The Key or associative array of key IDs
* (kid) to Key objects.
* If the algorithm used is asymmetric, this is
* the public key.
* Each Key object contains an algorithm and
* matching key.
* Supported algorithms are 'ES384','ES256',
* 'HS256', 'HS384', 'HS512', 'RS256', 'RS384'
* and 'RS512'.
* @param stdClass $headers Optional. Populates stdClass with headers.
*
* @return stdClass The JWT's payload as a PHP object
*
* @throws InvalidArgumentException Provided key/key-array was empty or malformed
* @throws DomainException Provided JWT is malformed
* @throws UnexpectedValueException Provided JWT was invalid
* @throws SignatureInvalidException Provided JWT was invalid because the signature verification failed
* @throws BeforeValidException Provided JWT is trying to be used before it's eligible as defined by 'nbf'
* @throws BeforeValidException Provided JWT is trying to be used before it's been created as defined by 'iat'
* @throws ExpiredException Provided JWT has since expired, as defined by the 'exp' claim
*
* @uses jsonDecode
* @uses urlsafeB64Decode
*/
public static function decode(
string $jwt,
$keyOrKeyArray,
stdClass &$headers = null
): stdClass {
// Validate JWT
$timestamp = \is_null(static::$timestamp) ? \time() : static::$timestamp;
if (empty($keyOrKeyArray)) {
throw new InvalidArgumentException('Key may not be empty');
}
$tks = \explode('.', $jwt);
if (\count($tks) !== 3) {
throw new UnexpectedValueException('Wrong number of segments');
}
list($headb64, $bodyb64, $cryptob64) = $tks;
$headerRaw = static::urlsafeB64Decode($headb64);
if (null === ($header = static::jsonDecode($headerRaw))) {
throw new UnexpectedValueException('Invalid header encoding');
}
if ($headers !== null) {
$headers = $header;
}
$payloadRaw = static::urlsafeB64Decode($bodyb64);
if (null === ($payload = static::jsonDecode($payloadRaw))) {
throw new UnexpectedValueException('Invalid claims encoding');
}
if (\is_array($payload)) {
// prevent PHP Fatal Error in edge-cases when payload is empty array
$payload = (object) $payload;
}
if (!$payload instanceof stdClass) {
throw new UnexpectedValueException('Payload must be a JSON object');
}
$sig = static::urlsafeB64Decode($cryptob64);
if (empty($header->alg)) {
throw new UnexpectedValueException('Empty algorithm');
}
if (empty(static::$supported_algs[$header->alg])) {
throw new UnexpectedValueException('Algorithm not supported');
}
$key = self::getKey($keyOrKeyArray, property_exists($header, 'kid') ? $header->kid : null);
// Check the algorithm
if (!self::constantTimeEquals($key->getAlgorithm(), $header->alg)) {
// See issue #351
throw new UnexpectedValueException('Incorrect key for this algorithm');
}
if (\in_array($header->alg, ['ES256', 'ES256K', 'ES384'], true)) {
// OpenSSL expects an ASN.1 DER sequence for ES256/ES256K/ES384 signatures
$sig = self::signatureToDER($sig);
}
if (!self::verify("{$headb64}.{$bodyb64}", $sig, $key->getKeyMaterial(), $header->alg)) {
throw new SignatureInvalidException('Signature verification failed');
}
// Check the nbf if it is defined. This is the time that the
// token can actually be used. If it's not yet that time, abort.
if (isset($payload->nbf) && floor($payload->nbf) > ($timestamp + static::$leeway)) {
$ex = new BeforeValidException(
'Cannot handle token with nbf prior to ' . \date(DateTime::ISO8601, (int) $payload->nbf)
);
$ex->setPayload($payload);
throw $ex;
}
// Check that this token has been created before 'now'. This prevents
// using tokens that have been created for later use (and haven't
// correctly used the nbf claim).
if (!isset($payload->nbf) && isset($payload->iat) && floor($payload->iat) > ($timestamp + static::$leeway)) {
$ex = new BeforeValidException(
'Cannot handle token with iat prior to ' . \date(DateTime::ISO8601, (int) $payload->iat)
);
$ex->setPayload($payload);
throw $ex;
}
// Check if this token has expired.
if (isset($payload->exp) && ($timestamp - static::$leeway) >= $payload->exp) {
$ex = new ExpiredException('Expired token');
$ex->setPayload($payload);
throw $ex;
}
return $payload;
}
/**
* Converts and signs a PHP array into a JWT string.
*
* @param array<mixed> $payload PHP array
* @param string|resource|OpenSSLAsymmetricKey|OpenSSLCertificate $key The secret key.
* @param string $alg Supported algorithms are 'ES384','ES256', 'ES256K', 'HS256',
* 'HS384', 'HS512', 'RS256', 'RS384', and 'RS512'
* @param string $keyId
* @param array<string, string> $head An array with header elements to attach
*
* @return string A signed JWT
*
* @uses jsonEncode
* @uses urlsafeB64Encode
*/
public static function encode(
array $payload,
$key,
string $alg,
string $keyId = null,
array $head = null
): string {
$header = ['typ' => 'JWT'];
if (isset($head) && \is_array($head)) {
$header = \array_merge($header, $head);
}
$header['alg'] = $alg;
if ($keyId !== null) {
$header['kid'] = $keyId;
}
$segments = [];
$segments[] = static::urlsafeB64Encode((string) static::jsonEncode($header));
$segments[] = static::urlsafeB64Encode((string) static::jsonEncode($payload));
$signing_input = \implode('.', $segments);
$signature = static::sign($signing_input, $key, $alg);
$segments[] = static::urlsafeB64Encode($signature);
return \implode('.', $segments);
}
/**
* Sign a string with a given key and algorithm.
*
* @param string $msg The message to sign
* @param string|resource|OpenSSLAsymmetricKey|OpenSSLCertificate $key The secret key.
* @param string $alg Supported algorithms are 'EdDSA', 'ES384', 'ES256', 'ES256K', 'HS256',
* 'HS384', 'HS512', 'RS256', 'RS384', and 'RS512'
*
* @return string An encrypted message
*
* @throws DomainException Unsupported algorithm or bad key was specified
*/
public static function sign(
string $msg,
$key,
string $alg
): string {
if (empty(static::$supported_algs[$alg])) {
throw new DomainException('Algorithm not supported');
}
list($function, $algorithm) = static::$supported_algs[$alg];
switch ($function) {
case 'hash_hmac':
if (!\is_string($key)) {
throw new InvalidArgumentException('key must be a string when using hmac');
}
return \hash_hmac($algorithm, $msg, $key, true);
case 'openssl':
$signature = '';
$success = \openssl_sign($msg, $signature, $key, $algorithm); // @phpstan-ignore-line
if (!$success) {
throw new DomainException('OpenSSL unable to sign data');
}
if ($alg === 'ES256' || $alg === 'ES256K') {
$signature = self::signatureFromDER($signature, 256);
} elseif ($alg === 'ES384') {
$signature = self::signatureFromDER($signature, 384);
}
return $signature;
case 'sodium_crypto':
if (!\function_exists('sodium_crypto_sign_detached')) {
throw new DomainException('libsodium is not available');
}
if (!\is_string($key)) {
throw new InvalidArgumentException('key must be a string when using EdDSA');
}
try {
// The last non-empty line is used as the key.
$lines = array_filter(explode("\n", $key));
$key = base64_decode((string) end($lines));
if (\strlen($key) === 0) {
throw new DomainException('Key cannot be empty string');
}
return sodium_crypto_sign_detached($msg, $key);
} catch (Exception $e) {
throw new DomainException($e->getMessage(), 0, $e);
}
}
throw new DomainException('Algorithm not supported');
}
/**
* Verify a signature with the message, key and method. Not all methods
* are symmetric, so we must have a separate verify and sign method.
*
* @param string $msg The original message (header and body)
* @param string $signature The original signature
* @param string|resource|OpenSSLAsymmetricKey|OpenSSLCertificate $keyMaterial For Ed*, ES*, HS*, a string key works. for RS*, must be an instance of OpenSSLAsymmetricKey
* @param string $alg The algorithm
*
* @return bool
*
* @throws DomainException Invalid Algorithm, bad key, or OpenSSL failure
*/
private static function verify(
string $msg,
string $signature,
$keyMaterial,
string $alg
): bool {
if (empty(static::$supported_algs[$alg])) {
throw new DomainException('Algorithm not supported');
}
list($function, $algorithm) = static::$supported_algs[$alg];
switch ($function) {
case 'openssl':
$success = \openssl_verify($msg, $signature, $keyMaterial, $algorithm); // @phpstan-ignore-line
if ($success === 1) {
return true;
}
if ($success === 0) {
return false;
}
// returns 1 on success, 0 on failure, -1 on error.
throw new DomainException(
'OpenSSL error: ' . \openssl_error_string()
);
case 'sodium_crypto':
if (!\function_exists('sodium_crypto_sign_verify_detached')) {
throw new DomainException('libsodium is not available');
}
if (!\is_string($keyMaterial)) {
throw new InvalidArgumentException('key must be a string when using EdDSA');
}
try {
// The last non-empty line is used as the key.
$lines = array_filter(explode("\n", $keyMaterial));
$key = base64_decode((string) end($lines));
if (\strlen($key) === 0) {
throw new DomainException('Key cannot be empty string');
}
if (\strlen($signature) === 0) {
throw new DomainException('Signature cannot be empty string');
}
return sodium_crypto_sign_verify_detached($signature, $msg, $key);
} catch (Exception $e) {
throw new DomainException($e->getMessage(), 0, $e);
}
case 'hash_hmac':
default:
if (!\is_string($keyMaterial)) {
throw new InvalidArgumentException('key must be a string when using hmac');
}
$hash = \hash_hmac($algorithm, $msg, $keyMaterial, true);
return self::constantTimeEquals($hash, $signature);
}
}
/**
* Decode a JSON string into a PHP object.
*
* @param string $input JSON string
*
* @return mixed The decoded JSON string
*
* @throws DomainException Provided string was invalid JSON
*/
public static function jsonDecode(string $input)
{
$obj = \json_decode($input, false, 512, JSON_BIGINT_AS_STRING);
if ($errno = \json_last_error()) {
self::handleJsonError($errno);
} elseif ($obj === null && $input !== 'null') {
throw new DomainException('Null result with non-null input');
}
return $obj;
}
/**
* Encode a PHP array into a JSON string.
*
* @param array<mixed> $input A PHP array
*
* @return string JSON representation of the PHP array
*
* @throws DomainException Provided object could not be encoded to valid JSON
*/
public static function jsonEncode(array $input): string
{
if (PHP_VERSION_ID >= 50400) {
$json = \json_encode($input, \JSON_UNESCAPED_SLASHES);
} else {
// PHP 5.3 only
$json = \json_encode($input);
}
if ($errno = \json_last_error()) {
self::handleJsonError($errno);
} elseif ($json === 'null') {
throw new DomainException('Null result with non-null input');
}
if ($json === false) {
throw new DomainException('Provided object could not be encoded to valid JSON');
}
return $json;
}
/**
* Decode a string with URL-safe Base64.
*
* @param string $input A Base64 encoded string
*
* @return string A decoded string
*
* @throws InvalidArgumentException invalid base64 characters
*/
public static function urlsafeB64Decode(string $input): string
{
return \base64_decode(self::convertBase64UrlToBase64($input));
}
/**
* Convert a string in the base64url (URL-safe Base64) encoding to standard base64.
*
* @param string $input A Base64 encoded string with URL-safe characters (-_ and no padding)
*
* @return string A Base64 encoded string with standard characters (+/) and padding (=), when
* needed.
*
* @see https://www.rfc-editor.org/rfc/rfc4648
*/
public static function convertBase64UrlToBase64(string $input): string
{
$remainder = \strlen($input) % 4;
if ($remainder) {
$padlen = 4 - $remainder;
$input .= \str_repeat('=', $padlen);
}
return \strtr($input, '-_', '+/');
}
/**
* Encode a string with URL-safe Base64.
*
* @param string $input The string you want encoded
*
* @return string The base64 encode of what you passed in
*/
public static function urlsafeB64Encode(string $input): string
{
return \str_replace('=', '', \strtr(\base64_encode($input), '+/', '-_'));
}
/**
* Determine if an algorithm has been provided for each Key
*
* @param Key|ArrayAccess<string,Key>|array<string,Key> $keyOrKeyArray
* @param string|null $kid
*
* @throws UnexpectedValueException
*
* @return Key
*/
private static function getKey(
$keyOrKeyArray,
?string $kid
): Key {
if ($keyOrKeyArray instanceof Key) {
return $keyOrKeyArray;
}
if (empty($kid) && $kid !== '0') {
throw new UnexpectedValueException('"kid" empty, unable to lookup correct key');
}
if ($keyOrKeyArray instanceof CachedKeySet) {
// Skip "isset" check, as this will automatically refresh if not set
return $keyOrKeyArray[$kid];
}
if (!isset($keyOrKeyArray[$kid])) {
throw new UnexpectedValueException('"kid" invalid, unable to lookup correct key');
}
return $keyOrKeyArray[$kid];
}
/**
* @param string $left The string of known length to compare against
* @param string $right The user-supplied string
* @return bool
*/
public static function constantTimeEquals(string $left, string $right): bool
{
if (\function_exists('hash_equals')) {
return \hash_equals($left, $right);
}
$len = \min(self::safeStrlen($left), self::safeStrlen($right));
$status = 0;
for ($i = 0; $i < $len; $i++) {
$status |= (\ord($left[$i]) ^ \ord($right[$i]));
}
$status |= (self::safeStrlen($left) ^ self::safeStrlen($right));
return ($status === 0);
}
/**
* Helper method to create a JSON error.
*
* @param int $errno An error number from json_last_error()
*
* @throws DomainException
*
* @return void
*/
private static function handleJsonError(int $errno): void
{
$messages = [
JSON_ERROR_DEPTH => 'Maximum stack depth exceeded',
JSON_ERROR_STATE_MISMATCH => 'Invalid or malformed JSON',
JSON_ERROR_CTRL_CHAR => 'Unexpected control character found',
JSON_ERROR_SYNTAX => 'Syntax error, malformed JSON',
JSON_ERROR_UTF8 => 'Malformed UTF-8 characters' //PHP >= 5.3.3
];
throw new DomainException(
isset($messages[$errno])
? $messages[$errno]
: 'Unknown JSON error: ' . $errno
);
}
/**
* Get the number of bytes in cryptographic strings.
*
* @param string $str
*
* @return int
*/
private static function safeStrlen(string $str): int
{
if (\function_exists('mb_strlen')) {
return \mb_strlen($str, '8bit');
}
return \strlen($str);
}
/**
* Convert an ECDSA signature to an ASN.1 DER sequence
*
* @param string $sig The ECDSA signature to convert
* @return string The encoded DER object
*/
private static function signatureToDER(string $sig): string
{
// Separate the signature into r-value and s-value
$length = max(1, (int) (\strlen($sig) / 2));
list($r, $s) = \str_split($sig, $length);
// Trim leading zeros
$r = \ltrim($r, "\x00");
$s = \ltrim($s, "\x00");
// Convert r-value and s-value from unsigned big-endian integers to
// signed two's complement
if (\ord($r[0]) > 0x7f) {
$r = "\x00" . $r;
}
if (\ord($s[0]) > 0x7f) {
$s = "\x00" . $s;
}
return self::encodeDER(
self::ASN1_SEQUENCE,
self::encodeDER(self::ASN1_INTEGER, $r) .
self::encodeDER(self::ASN1_INTEGER, $s)
);
}
/**
* Encodes a value into a DER object.
*
* @param int $type DER tag
* @param string $value the value to encode
*
* @return string the encoded object
*/
private static function encodeDER(int $type, string $value): string
{
$tag_header = 0;
if ($type === self::ASN1_SEQUENCE) {
$tag_header |= 0x20;
}
// Type
$der = \chr($tag_header | $type);
// Length
$der .= \chr(\strlen($value));
return $der . $value;
}
/**
* Encodes signature from a DER object.
*
* @param string $der binary signature in DER format
* @param int $keySize the number of bits in the key
*
* @return string the signature
*/
private static function signatureFromDER(string $der, int $keySize): string
{
// OpenSSL returns the ECDSA signatures as a binary ASN.1 DER SEQUENCE
list($offset, $_) = self::readDER($der);
list($offset, $r) = self::readDER($der, $offset);
list($offset, $s) = self::readDER($der, $offset);
// Convert r-value and s-value from signed two's compliment to unsigned
// big-endian integers
$r = \ltrim($r, "\x00");
$s = \ltrim($s, "\x00");
// Pad out r and s so that they are $keySize bits long
$r = \str_pad($r, $keySize / 8, "\x00", STR_PAD_LEFT);
$s = \str_pad($s, $keySize / 8, "\x00", STR_PAD_LEFT);
return $r . $s;
}
/**
* Reads binary DER-encoded data and decodes into a single object
*
* @param string $der the binary data in DER format
* @param int $offset the offset of the data stream containing the object
* to decode
*
* @return array{int, string|null} the new offset and the decoded object
*/
private static function readDER(string $der, int $offset = 0): array
{
$pos = $offset;
$size = \strlen($der);
$constructed = (\ord($der[$pos]) >> 5) & 0x01;
$type = \ord($der[$pos++]) & 0x1f;
// Length
$len = \ord($der[$pos++]);
if ($len & 0x80) {
$n = $len & 0x1f;
$len = 0;
while ($n-- && $pos < $size) {
$len = ($len << 8) | \ord($der[$pos++]);
}
}
// Value
if ($type === self::ASN1_BIT_STRING) {
$pos++; // Skip the first contents octet (padding indicator)
$data = \substr($der, $pos, $len - 1);
$pos += $len - 1;
} elseif (!$constructed) {
$data = \substr($der, $pos, $len);
$pos += $len;
} else {
$data = null;
}
return [$pos, $data];
}
}
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