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<?php
namespace Firebase\JWT;
use ArrayAccess;
use DomainException;
use Exception;
use InvalidArgumentException;
use OpenSSLAsymmetricKey;
use UnexpectedValueException;
use DateTime;
/**
* 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
{
const ASN1_INTEGER = 0x02;
const ASN1_SEQUENCE = 0x10;
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.
*/
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.
*/
public static $timestamp = null;
public static $supported_algs = array(
'ES384' => array('openssl', 'SHA384'),
'ES256' => array('openssl', 'SHA256'),
'HS256' => array('hash_hmac', 'SHA256'),
'HS384' => array('hash_hmac', 'SHA384'),
'HS512' => array('hash_hmac', 'SHA512'),
'RS256' => array('openssl', 'SHA256'),
'RS384' => array('openssl', 'SHA384'),
'RS512' => array('openssl', 'SHA512'),
'EdDSA' => array('sodium_crypto', 'EdDSA'),
);
/**
* Decodes a JWT string into a PHP object.
*
* @param string $jwt The JWT
* @param Key|array<Key>|mixed $keyOrKeyArray The Key or array of 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 array $allowed_algs [DEPRECATED] List of supported verification algorithms. Only
* should be used for backwards compatibility.
*
* @return object The JWT's payload as a PHP object
*
* @throws InvalidArgumentException Provided JWT was empty
* @throws UnexpectedValueException Provided JWT was invalid
* @throws SignatureInvalidException Provided JWT was invalid because the signature verification failed
* @throws BeforeValidException Provided JWT is trying to be used before it's eligible as defined by 'nbf'
* @throws BeforeValidException Provided JWT is trying to be used before it's been created as defined by 'iat'
* @throws ExpiredException Provided JWT has since expired, as defined by the 'exp' claim
*
* @uses jsonDecode
* @uses urlsafeB64Decode
*/
public static function decode($jwt, $keyOrKeyArray, array $allowed_algs = array())
{
$timestamp = \is_null(static::$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) = $tks;
if (null === ($header = static::jsonDecode(static::urlsafeB64Decode($headb64)))) {
throw new UnexpectedValueException('Invalid header encoding');
}
if (null === $payload = static::jsonDecode(static::urlsafeB64Decode($bodyb64))) {
throw new UnexpectedValueException('Invalid claims encoding');
}
if (false === ($sig = static::urlsafeB64Decode($cryptob64))) {
throw new UnexpectedValueException('Invalid signature encoding');
}
if (empty($header->alg)) {
throw new UnexpectedValueException('Empty algorithm');
}
if (empty(static::$supported_algs[$header->alg])) {
throw new UnexpectedValueException('Algorithm not supported');
}
list($keyMaterial, $algorithm) = self::getKeyMaterialAndAlgorithm(
$keyOrKeyArray,
empty($header->kid) ? null : $header->kid
);
if (empty($algorithm)) {
// Use deprecated "allowed_algs" to determine if the algorithm is supported.
// This opens up the possibility of an attack in some implementations.
// @see https://github.com/firebase/php-jwt/issues/351
if (!\in_array($header->alg, $allowed_algs)) {
throw new UnexpectedValueException('Algorithm not allowed');
}
} else {
// Check the algorithm
if (!self::constantTimeEquals($algorithm, $header->alg)) {
// See issue #351
throw new UnexpectedValueException('Incorrect key for this algorithm');
}
}
if ($header->alg === 'ES256' || $header->alg === 'ES384') {
// OpenSSL expects an ASN.1 DER sequence for ES256/ES384 signatures
$sig = self::signatureToDER($sig);
}
if (!static::verify("$headb64.$bodyb64", $sig, $keyMaterial, $header->alg)) {
throw new SignatureInvalidException('Signature verification failed');
}
// Check the nbf if it is defined. This is the time that the
// token can actually be used. If it's not yet that time, abort.
if (isset($payload->nbf) && $payload->nbf > ($timestamp + static::$leeway)) {
throw new BeforeValidException(
'Cannot handle token prior to ' . \date(DateTime::ISO8601, $payload->nbf)
);
}
// Check that this token has been created before 'now'. This prevents
// using tokens that have been created for later use (and haven't
// correctly used the nbf claim).
if (isset($payload->iat) && $payload->iat > ($timestamp + static::$leeway)) {
throw new BeforeValidException(
'Cannot handle token prior to ' . \date(DateTime::ISO8601, $payload->iat)
);
}
// Check if this token has expired.
if (isset($payload->exp) && ($timestamp - static::$leeway) >= $payload->exp) {
throw new ExpiredException('Expired token');
}
return $payload;
}
/**
* Converts and signs a PHP object or array into a JWT string.
*
* @param object|array $payload PHP object or array
* @param string|resource $key The secret key.
* If the algorithm used is asymmetric, this is the private key
* @param string $alg The signing algorithm.
* Supported algorithms are 'ES384','ES256', 'HS256', 'HS384',
* 'HS512', 'RS256', 'RS384', and 'RS512'
* @param mixed $keyId
* @param array $head An array with header elements to attach
*
* @return string A signed JWT
*
* @uses jsonEncode
* @uses urlsafeB64Encode
*/
public static function encode($payload, $key, $alg = 'HS256', $keyId = null, $head = null)
{
$header = array('typ' => 'JWT', 'alg' => $alg);
if ($keyId !== null) {
$header['kid'] = $keyId;
}
if (isset($head) && \is_array($head)) {
$header = \array_merge($head, $header);
}
$segments = array();
$segments[] = static::urlsafeB64Encode(static::jsonEncode($header));
$segments[] = static::urlsafeB64Encode(static::jsonEncode($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 $key The secret key
* @param string $alg The signing algorithm.
* Supported algorithms are 'ES384','ES256', 'HS256', 'HS384',
* 'HS512', 'RS256', 'RS384', and 'RS512'
*
* @return string An encrypted message
*
* @throws DomainException Unsupported algorithm or bad key was specified
*/
public static function sign($msg, $key, $alg = 'HS256')
{
if (empty(static::$supported_algs[$alg])) {
throw new DomainException('Algorithm not supported');
}
list($function, $algorithm) = static::$supported_algs[$alg];
switch ($function) {
case 'hash_hmac':
return \hash_hmac($algorithm, $msg, $key, true);
case 'openssl':
$signature = '';
$success = \openssl_sign($msg, $signature, $key, $algorithm);
if (!$success) {
throw new DomainException("OpenSSL unable to sign data");
}
if ($alg === 'ES256') {
$signature = self::signatureFromDER($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');
}
try {
// The last non-empty line is used as the key.
$lines = array_filter(explode("\n", $key));
$key = base64_decode(end($lines));
return sodium_crypto_sign_detached($msg, $key);
} catch (Exception $e) {
throw new DomainException($e->getMessage(), 0, $e);
}
}
}
/**
* 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 $key For HS*, a string key works. for RS*, must be a resource of an openssl public key
* @param string $alg The algorithm
*
* @return bool
*
* @throws DomainException Invalid Algorithm, bad key, or OpenSSL failure
*/
private static function verify($msg, $signature, $key, $alg)
{
if (empty(static::$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, $key, $algorithm);
if ($success === 1) {
return true;
} elseif ($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');
}
try {
// The last non-empty line is used as the key.
$lines = array_filter(explode("\n", $key));
$key = base64_decode(end($lines));
return sodium_crypto_sign_verify_detached($signature, $msg, $key);
} catch (Exception $e) {
throw new DomainException($e->getMessage(), 0, $e);
}
case 'hash_hmac':
default:
$hash = \hash_hmac($algorithm, $msg, $key, true);
return self::constantTimeEquals($signature, $hash);
}
}
/**
* Decode a JSON string into a PHP object.
*
* @param string $input JSON string
*
* @return object Object representation of JSON string
*
* @throws DomainException Provided string was invalid JSON
*/
public static function jsonDecode($input)
{
if (\version_compare(PHP_VERSION, '5.4.0', '>=') && !(\defined('JSON_C_VERSION') && PHP_INT_SIZE > 4)) {
/** In PHP >=5.4.0, json_decode() accepts an options parameter, that allows you
* to specify that large ints (like Steam Transaction IDs) should be treated as
* strings, rather than the PHP default behaviour of converting them to floats.
*/
$obj = \json_decode($input, false, 512, JSON_BIGINT_AS_STRING);
} else {
/** Not all servers will support that, however, so for older versions we must
* manually detect large ints in the JSON string and quote them (thus converting
*them to strings) before decoding, hence the preg_replace() call.
*/
$max_int_length = \strlen((string) PHP_INT_MAX) - 1;
$json_without_bigints = \preg_replace('/:\s*(-?\d{'.$max_int_length.',})/', ': "$1"', $input);
$obj = \json_decode($json_without_bigints);
}
if ($errno = \json_last_error()) {
static::handleJsonError($errno);
} elseif ($obj === null && $input !== 'null') {
throw new DomainException('Null result with non-null input');
}
return $obj;
}
/**
* Encode a PHP object into a JSON string.
*
* @param object|array $input A PHP object or array
*
* @return string JSON representation of the PHP object or array
*
* @throws DomainException Provided object could not be encoded to valid JSON
*/
public static function jsonEncode($input)
{
$json = \json_encode($input);
if ($errno = \json_last_error()) {
static::handleJsonError($errno);
} elseif ($json === 'null' && $input !== null) {
throw new DomainException('Null result with non-null input');
}
return $json;
}
/**
* Decode a string with URL-safe Base64.
*
* @param string $input A Base64 encoded string
*
* @return string A decoded string
*/
public static function urlsafeB64Decode($input)
{
$remainder = \strlen($input) % 4;
if ($remainder) {
$padlen = 4 - $remainder;
$input .= \str_repeat('=', $padlen);
}
return \base64_decode(\strtr($input, '-_', '+/'));
}
/**
* Encode a string with URL-safe Base64.
*
* @param string $input The string you want encoded
*
* @return string The base64 encode of what you passed in
*/
public static function urlsafeB64Encode($input)
{
return \str_replace('=', '', \strtr(\base64_encode($input), '+/', '-_'));
}
/**
* Determine if an algorithm has been provided for each Key
*
* @param Key|array<Key>|mixed $keyOrKeyArray
* @param string|null $kid
*
* @throws UnexpectedValueException
*
* @return array containing the keyMaterial and algorithm
*/
private static function getKeyMaterialAndAlgorithm($keyOrKeyArray, $kid = null)
{
if (
is_string($keyOrKeyArray)
|| is_resource($keyOrKeyArray)
|| $keyOrKeyArray instanceof OpenSSLAsymmetricKey
) {
return array($keyOrKeyArray, null);
}
if ($keyOrKeyArray instanceof Key) {
return array($keyOrKeyArray->getKeyMaterial(), $keyOrKeyArray->getAlgorithm());
}
if (is_array($keyOrKeyArray) || $keyOrKeyArray instanceof ArrayAccess) {
if (!isset($kid)) {
throw new UnexpectedValueException('"kid" empty, unable to lookup correct key');
}
if (!isset($keyOrKeyArray[$kid])) {
throw new UnexpectedValueException('"kid" invalid, unable to lookup correct key');
}
$key = $keyOrKeyArray[$kid];
if ($key instanceof Key) {
return array($key->getKeyMaterial(), $key->getAlgorithm());
}
return array($key, null);
}
throw new UnexpectedValueException(
'$keyOrKeyArray must be a string|resource key, an array of string|resource keys, '
. 'an instance of Firebase\JWT\Key key or an array of Firebase\JWT\Key keys'
);
}
/**
* @param string $left
* @param string $right
* @return bool
*/
public static function constantTimeEquals($left, $right)
{
if (\function_exists('hash_equals')) {
return \hash_equals($left, $right);
}
$len = \min(static::safeStrlen($left), static::safeStrlen($right));
$status = 0;
for ($i = 0; $i < $len; $i++) {
$status |= (\ord($left[$i]) ^ \ord($right[$i]));
}
$status |= (static::safeStrlen($left) ^ static::safeStrlen($right));
return ($status === 0);
}
/**
* Helper method to create a JSON error.
*
* @param int $errno An error number from json_last_error()
*
* @return void
*/
private static function handleJsonError($errno)
{
$messages = array(
JSON_ERROR_DEPTH => 'Maximum stack depth exceeded',
JSON_ERROR_STATE_MISMATCH => 'Invalid or malformed JSON',
JSON_ERROR_CTRL_CHAR => 'Unexpected control character found',
JSON_ERROR_SYNTAX => 'Syntax error, malformed JSON',
JSON_ERROR_UTF8 => 'Malformed UTF-8 characters' //PHP >= 5.3.3
);
throw new DomainException(
isset($messages[$errno])
? $messages[$errno]
: 'Unknown JSON error: ' . $errno
);
}
/**
* Get the number of bytes in cryptographic strings.
*
* @param string $str
*
* @return int
*/
private static function safeStrlen($str)
{
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 $sig The ECDSA signature to convert
* @return string The encoded DER object
*/
private static function signatureToDER($sig)
{
// Separate the signature into r-value and s-value
list($r, $s) = \str_split($sig, (int) (\strlen($sig) / 2));
// 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 $value the value to encode
* @return string the encoded object
*/
private static function encodeDER($type, $value)
{
$tag_header = 0;
if ($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 $keySize the number of bits in the key
* @return string the signature
*/
private static function signatureFromDER($der, $keySize)
{
// OpenSSL returns the ECDSA signatures as a binary ASN.1 DER SEQUENCE
list($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 $offset the offset of the data stream containing the object
* to decode
* @return array [$offset, $data] the new offset and the decoded object
*/
private static function readDER($der, $offset = 0)
{
$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 {
$data = null;
}
return array($pos, $data);
}
}
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