Proyectos de Subversion Moodle

<?php

// phpcs:ignoreFile

namespace Firebase\JWT;

use DomainException;

use Exception;

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 <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 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 'ES384','ES256', 'HS256', 'HS384',

     *                                                  'HS512', 'RS256', 'RS384', and 'RS512'

     *

     * @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, $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' || $header->alg === 'ES384') {

            // OpenSSL expects an ASN.1 DER sequence for ES256/ES384 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|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);

                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' //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);

    }

}