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<?php
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namespace lbuchs\WebAuthn\Attestation\Format;
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use lbuchs\WebAuthn\Attestation\AuthenticatorData;
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use lbuchs\WebAuthn\WebAuthnException;
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use lbuchs\WebAuthn\Binary\ByteBuffer;
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class Packed extends FormatBase {
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    private $_alg;
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    private $_signature;
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    private $_x5c;
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    public function __construct($AttestionObject, AuthenticatorData $authenticatorData) {
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        parent::__construct($AttestionObject, $authenticatorData);
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        // check packed data
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        $attStmt = $this->_attestationObject['attStmt'];
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        if (!\array_key_exists('alg', $attStmt) || $this->_getCoseAlgorithm($attStmt['alg']) === null) {
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            throw new WebAuthnException('unsupported alg: ' . $attStmt['alg'], WebAuthnException::INVALID_DATA);
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        }
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        if (!\array_key_exists('sig', $attStmt) || !\is_object($attStmt['sig']) || !($attStmt['sig'] instanceof ByteBuffer)) {
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            throw new WebAuthnException('no signature found', WebAuthnException::INVALID_DATA);
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        }
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        $this->_alg = $attStmt['alg'];
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        $this->_signature = $attStmt['sig']->getBinaryString();
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        // certificate for validation
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        if (\array_key_exists('x5c', $attStmt) && \is_array($attStmt['x5c']) && \count($attStmt['x5c']) > 0) {
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            // The attestation certificate attestnCert MUST be the first element in the array
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            $attestnCert = array_shift($attStmt['x5c']);
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            if (!($attestnCert instanceof ByteBuffer)) {
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                throw new WebAuthnException('invalid x5c certificate', WebAuthnException::INVALID_DATA);
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            }
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            $this->_x5c = $attestnCert->getBinaryString();
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            // certificate chain
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            foreach ($attStmt['x5c'] as $chain) {
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                if ($chain instanceof ByteBuffer) {
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                    $this->_x5c_chain[] = $chain->getBinaryString();
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                }
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            }
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        }
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    }
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    /*
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     * returns the key certificate in PEM format
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     * @return string|null
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     */
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    public function getCertificatePem() {
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        if (!$this->_x5c) {
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            return null;
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        }
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        return $this->_createCertificatePem($this->_x5c);
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    }
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    /**
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     * @param string $clientDataHash
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     */
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    public function validateAttestation($clientDataHash) {
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        if ($this->_x5c) {
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            return $this->_validateOverX5c($clientDataHash);
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        } else {
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            return $this->_validateSelfAttestation($clientDataHash);
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        }
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    }
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    /**
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     * validates the certificate against root certificates
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     * @param array $rootCas
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     * @return boolean
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     * @throws WebAuthnException
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     */
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    public function validateRootCertificate($rootCas) {
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        if (!$this->_x5c) {
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            return false;
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        }
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        $chainC = $this->_createX5cChainFile();
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        if ($chainC) {
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            $rootCas[] = $chainC;
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        }
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        $v = \openssl_x509_checkpurpose($this->getCertificatePem(), -1, $rootCas);
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        if ($v === -1) {
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            throw new WebAuthnException('error on validating root certificate: ' . \openssl_error_string(), WebAuthnException::CERTIFICATE_NOT_TRUSTED);
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        }
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        return $v;
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    }
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    /**
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     * validate if x5c is present
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     * @param string $clientDataHash
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     * @return bool
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     * @throws WebAuthnException
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     */
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    protected function _validateOverX5c($clientDataHash) {
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        $publicKey = \openssl_pkey_get_public($this->getCertificatePem());
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        if ($publicKey === false) {
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            throw new WebAuthnException('invalid public key: ' . \openssl_error_string(), WebAuthnException::INVALID_PUBLIC_KEY);
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        }
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        // Verify that sig is a valid signature over the concatenation of authenticatorData and clientDataHash
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        // using the attestation public key in attestnCert with the algorithm specified in alg.
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        $dataToVerify = $this->_authenticatorData->getBinary();
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        $dataToVerify .= $clientDataHash;
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        $coseAlgorithm = $this->_getCoseAlgorithm($this->_alg);
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        // check certificate
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        return \openssl_verify($dataToVerify, $this->_signature, $publicKey, $coseAlgorithm->openssl) === 1;
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    }
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    /**
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     * validate if self attestation is in use
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     * @param string $clientDataHash
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     * @return bool
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     */
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    protected function _validateSelfAttestation($clientDataHash) {
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        // Verify that sig is a valid signature over the concatenation of authenticatorData and clientDataHash
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        // using the credential public key with alg.
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        $dataToVerify = $this->_authenticatorData->getBinary();
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        $dataToVerify .= $clientDataHash;
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        $publicKey = $this->_authenticatorData->getPublicKeyPem();
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        // check certificate
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        return \openssl_verify($dataToVerify, $this->_signature, $publicKey, OPENSSL_ALGO_SHA256) === 1;
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    }
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}
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