JWT.php in Auth0 Single Sign On 8.2

Namespace

Firebase\JWT

File

vendor/firebase/php-jwt/src/JWT.php

<?php

namespace Firebase\JWT;

use DomainException;
use InvalidArgumentException;
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 <[e-mail]>
 * @author   Anant Narayanan <[e-mail]>
 * @license  http://opensource.org/licenses/BSD-3-Clause 3-clause BSD
 * @link     https://github.com/firebase/php-jwt
 */
class JWT {
  const ASN1_INTEGER = 0x2;
  const ASN1_SEQUENCE = 0x10;
  const ASN1_BIT_STRING = 0x3;

  /**
   * 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(
    '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',
    ),
  );

  /**
   * Decodes a JWT string into a PHP object.
   *
   * @param string                    $jwt            The JWT
   * @param string|array|resource     $key            The key, or map of keys.
   *                                                  If the algorithm used is asymmetric, this is the public key
   * @param array                     $allowed_algs   List of supported verification algorithms
   *                                                  Supported algorithms are 'ES256', 'HS256', 'HS384', 'HS512', 'RS256', 'RS384', and 'RS512'
   *
   * @return object The JWT's payload as a PHP object
   *
   * @throws UnexpectedValueException     Provided JWT was invalid
   * @throws SignatureInvalidException    Provided JWT was invalid because the signature verification failed
   * @throws BeforeValidException         Provided JWT is trying to be used before it's eligible as defined by 'nbf'
   * @throws BeforeValidException         Provided JWT is trying to be used before it's been created as defined by 'iat'
   * @throws ExpiredException             Provided JWT has since expired, as defined by the 'exp' claim
   *
   * @uses jsonDecode
   * @uses urlsafeB64Decode
   */
  public static function decode($jwt, $key, array $allowed_algs = array()) {
    $timestamp = \is_null(static::$timestamp) ? \time() : static::$timestamp;
    if (empty($key)) {
      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');
    }
    if (!\in_array($header->alg, $allowed_algs)) {
      throw new UnexpectedValueException('Algorithm not allowed');
    }
    if ($header->alg === 'ES256') {

      // OpenSSL expects an ASN.1 DER sequence for ES256 signatures
      $sig = self::signatureToDER($sig);
    }
    if (\is_array($key) || $key instanceof \ArrayAccess) {
      if (isset($header->kid)) {
        if (!isset($key[$header->kid])) {
          throw new UnexpectedValueException('"kid" invalid, unable to lookup correct key');
        }
        $key = $key[$header->kid];
      }
      else {
        throw new UnexpectedValueException('"kid" empty, unable to lookup correct key');
      }
    }

    // Check the signature
    if (!static::verify("{$headb64}.{$bodyb64}", $sig, $key, $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        $key        The secret key.
   *                                  If the algorithm used is asymmetric, this is the private key
   * @param string        $alg        The signing algorithm.
   *                                  Supported algorithms are '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            $alg    The signing algorithm.
   *                                  Supported algorithms are 'ES256', 'HS256', 'HS384', 'HS512', 'RS256', 'RS384', and 'RS512'
   *
   * @return string An encrypted message
   *
   * @throws DomainException Unsupported algorithm was specified
   */
  public static function sign($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");
        }
        else {
          if ($alg === 'ES256') {
            $signature = self::signatureFromDER($signature, 256);
          }
          return $signature;
        }
    }
  }

  /**
   * 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            $alg        The algorithm
   *
   * @return bool
   *
   * @throws DomainException Invalid Algorithm or OpenSSL failure
   */
  private static function verify($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 'hash_hmac':
      default:
        $hash = \hash_hmac($algorithm, $msg, $key, true);
        if (\function_exists('hash_equals')) {
          return \hash_equals($signature, $hash);
        }
        $len = \min(static::safeStrlen($signature), static::safeStrlen($hash));
        $status = 0;
        for ($i = 0; $i < $len; $i++) {
          $status |= \ord($signature[$i]) ^ \ord($hash[$i]);
        }
        $status |= static::safeStrlen($signature) ^ static::safeStrlen($hash);
        return $status === 0;
    }
  }

  /**
   * 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), '+/', '-_'));
  }

  /**
   * Helper method to create a JSON error.
   *
   * @param int $errno An error number from json_last_error()
   *
   * @return void
   */
  private static function handleJsonError($errno) {
    $messages = array(
      JSON_ERROR_DEPTH => 'Maximum stack depth exceeded',
      JSON_ERROR_STATE_MISMATCH => 'Invalid or malformed JSON',
      JSON_ERROR_CTRL_CHAR => 'Unexpected control character found',
      JSON_ERROR_SYNTAX => 'Syntax error, malformed JSON',
      JSON_ERROR_UTF8 => 'Malformed UTF-8 characters',
    );
    throw new DomainException(isset($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, "\0");
    $s = \ltrim($s, "\0");

    // Convert r-value and s-value from unsigned big-endian integers to
    // signed two's complement
    if (\ord($r[0]) > 0x7f) {
      $r = "\0" . $r;
    }
    if (\ord($s[0]) > 0x7f) {
      $s = "\0" . $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, "\0");
    $s = \ltrim($s, "\0");

    // Pad out r and s so that they are $keySize bits long
    $r = \str_pad($r, $keySize / 8, "\0", STR_PAD_LEFT);
    $s = \str_pad($s, $keySize / 8, "\0", 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 & 0x1;
    $type = \ord($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,
    );
  }

}

Classes

Name	Description
JWT	JSON Web Token implementation, based on this spec: https://tools.ietf.org/html/rfc7519