Proyectos de Subversion Moodle

<?php

namespace lbuchs\WebAuthn\Attestation\Format;

use lbuchs\WebAuthn\Attestation\AuthenticatorData;

use lbuchs\WebAuthn\WebAuthnException;

use lbuchs\WebAuthn\Binary\ByteBuffer;

class AndroidSafetyNet extends FormatBase {

    private $_signature;

    private $_signedValue;

    private $_x5c;

    private $_payload;

    public function __construct($AttestionObject, AuthenticatorData $authenticatorData) {

        parent::__construct($AttestionObject, $authenticatorData);

        // check data

        $attStmt = $this->_attestationObject['attStmt'];

        if (!\array_key_exists('ver', $attStmt) || !$attStmt['ver']) {

            throw new WebAuthnException('invalid Android Safety Net Format', WebAuthnException::INVALID_DATA);

        }

        if (!\array_key_exists('response', $attStmt) || !($attStmt['response'] instanceof ByteBuffer)) {

            throw new WebAuthnException('invalid Android Safety Net Format', WebAuthnException::INVALID_DATA);

        }

        $response = $attStmt['response']->getBinaryString();

        // Response is a JWS [RFC7515] object in Compact Serialization.

        // JWSs have three segments separated by two period ('.') characters

        $parts = \explode('.', $response);

        unset ($response);

        if (\count($parts) !== 3) {

            throw new WebAuthnException('invalid JWS data', WebAuthnException::INVALID_DATA);

        }

        $header = $this->_base64url_decode($parts[0]);

        $payload = $this->_base64url_decode($parts[1]);

        $this->_signature = $this->_base64url_decode($parts[2]);

        $this->_signedValue = $parts[0] . '.' . $parts[1];

        unset ($parts);

        $header = \json_decode($header);

        $payload = \json_decode($payload);

        if (!($header instanceof \stdClass)) {

            throw new WebAuthnException('invalid JWS header', WebAuthnException::INVALID_DATA);

        }

        if (!($payload instanceof \stdClass)) {

            throw new WebAuthnException('invalid JWS payload', WebAuthnException::INVALID_DATA);

        }

        if (!isset($header->x5c) || !is_array($header->x5c) || count($header->x5c) === 0) {

            throw new WebAuthnException('No X.509 signature in JWS Header', WebAuthnException::INVALID_DATA);

        }

        // algorithm

        if (!\in_array($header->alg, array('RS256', 'ES256'))) {

            throw new WebAuthnException('invalid JWS algorithm ' . $header->alg, WebAuthnException::INVALID_DATA);

        }

        $this->_x5c = \base64_decode($header->x5c[0]);

        $this->_payload = $payload;

        if (count($header->x5c) > 1) {

            for ($i=1; $i<count($header->x5c); $i++) {

                $this->_x5c_chain[] = \base64_decode($header->x5c[$i]);

            }

            unset ($i);

        }

    }

    /**

     * ctsProfileMatch: A stricter verdict of device integrity.

     * If the value of ctsProfileMatch is true, then the profile of the device running your app matches

     * the profile of a device that has passed Android compatibility testing and

     * has been approved as a Google-certified Android device.

     * @return bool

     */

    public function ctsProfileMatch() {

        return isset($this->_payload->ctsProfileMatch) ? !!$this->_payload->ctsProfileMatch : false;

    }

    /*

     * returns the key certificate in PEM format

     * @return string

     */

    public function getCertificatePem() {

        return $this->_createCertificatePem($this->_x5c);

    }

    /**

     * @param string $clientDataHash

     */

    public function validateAttestation($clientDataHash) {

        $publicKey = \openssl_pkey_get_public($this->getCertificatePem());

        // Verify that the nonce in the response is identical to the Base64 encoding

        // of the SHA-256 hash of the concatenation of authenticatorData and clientDataHash.

        if (empty($this->_payload->nonce) || $this->_payload->nonce !== \base64_encode(\hash('SHA256', $this->_authenticatorData->getBinary() . $clientDataHash, true))) {

            throw new WebAuthnException('invalid nonce in JWS payload', WebAuthnException::INVALID_DATA);

        }

        // Verify that attestationCert is issued to the hostname "attest.android.com"

        $certInfo = \openssl_x509_parse($this->getCertificatePem());

        if (!\is_array($certInfo) || ($certInfo['subject']['CN'] ?? '') !== 'attest.android.com') {

            throw new WebAuthnException('invalid certificate CN in JWS (' . ($certInfo['subject']['CN'] ?? '-'). ')', WebAuthnException::INVALID_DATA);

        }

        // Verify that the basicIntegrity attribute in the payload of response is true.

        if (empty($this->_payload->basicIntegrity)) {

            throw new WebAuthnException('invalid basicIntegrity in payload', WebAuthnException::INVALID_DATA);

        }

        // check certificate

        return \openssl_verify($this->_signedValue, $this->_signature, $publicKey, OPENSSL_ALGO_SHA256) === 1;

    }

    /**

     * validates the certificate against root certificates

     * @param array $rootCas

     * @return boolean

     * @throws WebAuthnException

     */

    public function validateRootCertificate($rootCas) {

        $chainC = $this->_createX5cChainFile();

        if ($chainC) {

            $rootCas[] = $chainC;

        }

        $v = \openssl_x509_checkpurpose($this->getCertificatePem(), -1, $rootCas);

        if ($v === -1) {

            throw new WebAuthnException('error on validating root certificate: ' . \openssl_error_string(), WebAuthnException::CERTIFICATE_NOT_TRUSTED);

        }

        return $v;

    }

    /**

     * decode base64 url

     * @param string $data

     * @return string

     */

    private function _base64url_decode($data) {

        return \base64_decode(\strtr($data, '-_', '+/') . \str_repeat('=', 3 - (3 + \strlen($data)) % 4));

    }

}