140 lines
5.1 KiB
PHP
140 lines
5.1 KiB
PHP
<?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 Apple extends FormatBase {
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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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// 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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} else {
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throw new WebAuthnException('invalid Apple attestation statement: missing x5c', WebAuthnException::INVALID_DATA);
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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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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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return $this->_validateOverX5c($clientDataHash);
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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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$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 ($publicKey === false) {
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throw new WebAuthnException('invalid public key: ' . \openssl_error_string(), WebAuthnException::INVALID_PUBLIC_KEY);
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}
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// Concatenate authenticatorData and clientDataHash to form nonceToHash.
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$nonceToHash = $this->_authenticatorData->getBinary();
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$nonceToHash .= $clientDataHash;
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// Perform SHA-256 hash of nonceToHash to produce nonce
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$nonce = hash('SHA256', $nonceToHash, true);
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$credCert = openssl_x509_read($this->getCertificatePem());
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if ($credCert === false) {
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throw new WebAuthnException('invalid x5c certificate: ' . \openssl_error_string(), WebAuthnException::INVALID_DATA);
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}
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$keyData = openssl_pkey_get_details(openssl_pkey_get_public($credCert));
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$key = is_array($keyData) && array_key_exists('key', $keyData) ? $keyData['key'] : null;
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// Verify that nonce equals the value of the extension with OID ( 1.2.840.113635.100.8.2 ) in credCert.
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$parsedCredCert = openssl_x509_parse($credCert);
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$nonceExtension = isset($parsedCredCert['extensions']['1.2.840.113635.100.8.2']) ? $parsedCredCert['extensions']['1.2.840.113635.100.8.2'] : '';
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// nonce padded by ASN.1 string: 30 24 A1 22 04 20
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// 30 — type tag indicating sequence
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// 24 — 36 byte following
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// A1 — Enumerated [1]
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// 22 — 34 byte following
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// 04 — type tag indicating octet string
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// 20 — 32 byte following
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$asn1Padding = "\x30\x24\xA1\x22\x04\x20";
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if (substr($nonceExtension, 0, strlen($asn1Padding)) === $asn1Padding) {
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$nonceExtension = substr($nonceExtension, strlen($asn1Padding));
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}
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if ($nonceExtension !== $nonce) {
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throw new WebAuthnException('nonce doesn\'t equal the value of the extension with OID 1.2.840.113635.100.8.2', WebAuthnException::INVALID_DATA);
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}
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// Verify that the credential public key equals the Subject Public Key of credCert.
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$authKeyData = openssl_pkey_get_details(openssl_pkey_get_public($this->_authenticatorData->getPublicKeyPem()));
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$authKey = is_array($authKeyData) && array_key_exists('key', $authKeyData) ? $authKeyData['key'] : null;
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if ($key === null || $key !== $authKey) {
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throw new WebAuthnException('credential public key doesn\'t equal the Subject Public Key of credCert', WebAuthnException::INVALID_DATA);
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}
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return true;
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}
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}
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