| <?php |
| |
| |
| namespace lbuchs\WebAuthn\Attestation\Format; |
| use lbuchs\WebAuthn\Attestation\AuthenticatorData; |
| use lbuchs\WebAuthn\WebAuthnException; |
| use lbuchs\WebAuthn\Binary\ByteBuffer; |
| |
| class Apple extends FormatBase { |
| private $_x5c; |
| |
| public function __construct($AttestionObject, AuthenticatorData $authenticatorData) { |
| parent::__construct($AttestionObject, $authenticatorData); |
| |
| // check packed data |
| $attStmt = $this->_attestationObject['attStmt']; |
| |
| |
| // certificate for validation |
| if (\array_key_exists('x5c', $attStmt) && \is_array($attStmt['x5c']) && \count($attStmt['x5c']) > 0) { |
| |
| // The attestation certificate attestnCert MUST be the first element in the array |
| $attestnCert = array_shift($attStmt['x5c']); |
| |
| if (!($attestnCert instanceof ByteBuffer)) { |
| throw new WebAuthnException('invalid x5c certificate', WebAuthnException::INVALID_DATA); |
| } |
| |
| $this->_x5c = $attestnCert->getBinaryString(); |
| |
| // certificate chain |
| foreach ($attStmt['x5c'] as $chain) { |
| if ($chain instanceof ByteBuffer) { |
| $this->_x5c_chain[] = $chain->getBinaryString(); |
| } |
| } |
| } else { |
| throw new WebAuthnException('invalid Apple attestation statement: missing x5c', WebAuthnException::INVALID_DATA); |
| } |
| } |
| |
| |
| /* |
| * returns the key certificate in PEM format |
| * @return string|null |
| */ |
| public function getCertificatePem() { |
| return $this->_createCertificatePem($this->_x5c); |
| } |
| |
| /** |
| * @param string $clientDataHash |
| */ |
| public function validateAttestation($clientDataHash) { |
| return $this->_validateOverX5c($clientDataHash); |
| } |
| |
| /** |
| * 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; |
| } |
| |
| /** |
| * validate if x5c is present |
| * @param string $clientDataHash |
| * @return bool |
| * @throws WebAuthnException |
| */ |
| protected function _validateOverX5c($clientDataHash) { |
| $publicKey = \openssl_pkey_get_public($this->getCertificatePem()); |
| |
| if ($publicKey === false) { |
| throw new WebAuthnException('invalid public key: ' . \openssl_error_string(), WebAuthnException::INVALID_PUBLIC_KEY); |
| } |
| |
| // Concatenate authenticatorData and clientDataHash to form nonceToHash. |
| $nonceToHash = $this->_authenticatorData->getBinary(); |
| $nonceToHash .= $clientDataHash; |
| |
| // Perform SHA-256 hash of nonceToHash to produce nonce |
| $nonce = hash('SHA256', $nonceToHash, true); |
| |
| $credCert = openssl_x509_read($this->getCertificatePem()); |
| if ($credCert === false) { |
| throw new WebAuthnException('invalid x5c certificate: ' . \openssl_error_string(), WebAuthnException::INVALID_DATA); |
| } |
| |
| $keyData = openssl_pkey_get_details(openssl_pkey_get_public($credCert)); |
| $key = is_array($keyData) && array_key_exists('key', $keyData) ? $keyData['key'] : null; |
| |
| |
| // Verify that nonce equals the value of the extension with OID ( 1.2.840.113635.100.8.2 ) in credCert. |
| $parsedCredCert = openssl_x509_parse($credCert); |
| $nonceExtension = $parsedCredCert['extensions']['1.2.840.113635.100.8.2'] ?? ''; |
| |
| // nonce padded by ASN.1 string: 30 24 A1 22 04 20 |
| // 30 — type tag indicating sequence |
| // 24 — 36 byte following |
| // A1 — Enumerated [1] |
| // 22 — 34 byte following |
| // 04 — type tag indicating octet string |
| // 20 — 32 byte following |
| |
| $asn1Padding = "\x30\x24\xA1\x22\x04\x20"; |
| if (substr($nonceExtension, 0, strlen($asn1Padding)) === $asn1Padding) { |
| $nonceExtension = substr($nonceExtension, strlen($asn1Padding)); |
| } |
| |
| if ($nonceExtension !== $nonce) { |
| throw new WebAuthnException('nonce doesn\'t equal the value of the extension with OID 1.2.840.113635.100.8.2', WebAuthnException::INVALID_DATA); |
| } |
| |
| // Verify that the credential public key equals the Subject Public Key of credCert. |
| $authKeyData = openssl_pkey_get_details(openssl_pkey_get_public($this->_authenticatorData->getPublicKeyPem())); |
| $authKey = is_array($authKeyData) && array_key_exists('key', $authKeyData) ? $authKeyData['key'] : null; |
| |
| if ($key === null || $key !== $authKey) { |
| throw new WebAuthnException('credential public key doesn\'t equal the Subject Public Key of credCert', WebAuthnException::INVALID_DATA); |
| } |
| |
| return true; |
| } |
| |
| } |
| |