blob: e4f38e0ee6a8efc794141171d14b9903603c6841 [file] [log] [blame]
<?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;
}
}