Proyectos de Subversion Moodle

<?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];

    }

}