mailcow/data/web/inc/lib/WebAuthn/WebAuthn.php

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<?php
namespace lbuchs\WebAuthn;
use lbuchs\WebAuthn\Binary\ByteBuffer;
require_once 'WebAuthnException.php';
require_once 'Binary/ByteBuffer.php';
require_once 'Attestation/AttestationObject.php';
require_once 'Attestation/AuthenticatorData.php';
require_once 'Attestation/Format/FormatBase.php';
require_once 'Attestation/Format/None.php';
require_once 'Attestation/Format/AndroidKey.php';
require_once 'Attestation/Format/AndroidSafetyNet.php';
require_once 'Attestation/Format/Apple.php';
require_once 'Attestation/Format/Packed.php';
require_once 'Attestation/Format/Tpm.php';
require_once 'Attestation/Format/U2f.php';
require_once 'CBOR/CborDecoder.php';
/**
* WebAuthn
* @author Lukas Buchs
* @license https://github.com/lbuchs/WebAuthn/blob/master/LICENSE MIT
*/
class WebAuthn {
// relying party
private $_rpName;
private $_rpId;
private $_rpIdHash;
private $_challenge;
private $_signatureCounter;
private $_caFiles;
private $_formats;
/**
* Initialize a new WebAuthn server
* @param string $rpName the relying party name
* @param string $rpId the relying party ID = the domain name
* @param bool $useBase64UrlEncoding true to use base64 url encoding for binary data in json objects. Default is a RFC 1342-Like serialized string.
* @throws WebAuthnException
*/
public function __construct($rpName, $rpId, $allowedFormats=null, $useBase64UrlEncoding=false) {
$this->_rpName = $rpName;
$this->_rpId = $rpId;
$this->_rpIdHash = \hash('sha256', $rpId, true);
ByteBuffer::$useBase64UrlEncoding = !!$useBase64UrlEncoding;
$supportedFormats = array('android-key', 'android-safetynet', 'apple', 'fido-u2f', 'none', 'packed', 'tpm');
if (!\function_exists('\openssl_open')) {
throw new WebAuthnException('OpenSSL-Module not installed');;
}
if (!\in_array('SHA256', \array_map('\strtoupper', \openssl_get_md_methods()))) {
throw new WebAuthnException('SHA256 not supported by this openssl installation.');
}
// default: all format
if (!is_array($allowedFormats)) {
$allowedFormats = $supportedFormats;
}
$this->_formats = $allowedFormats;
// validate formats
$invalidFormats = \array_diff($this->_formats, $supportedFormats);
if (!$this->_formats || $invalidFormats) {
throw new WebAuthnException('invalid formats on construct: ' . implode(', ', $invalidFormats));
}
}
/**
* add a root certificate to verify new registrations
* @param string $path file path of / directory with root certificates
* @param array|null $certFileExtensions if adding a direction, all files with provided extension are added. default: pem, crt, cer, der
*/
public function addRootCertificates($path, $certFileExtensions=null) {
if (!\is_array($this->_caFiles)) {
$this->_caFiles = array();
}
if ($certFileExtensions === null) {
$certFileExtensions = array('pem', 'crt', 'cer', 'der');
}
$path = \rtrim(\trim($path), '\\/');
if (\is_dir($path)) {
foreach (\scandir($path) as $ca) {
if (\is_file($path . DIRECTORY_SEPARATOR . $ca) && \in_array(\strtolower(\pathinfo($ca, PATHINFO_EXTENSION)), $certFileExtensions)) {
$this->addRootCertificates($path . DIRECTORY_SEPARATOR . $ca);
}
}
} else if (\is_file($path) && !\in_array(\realpath($path), $this->_caFiles)) {
$this->_caFiles[] = \realpath($path);
}
}
/**
* Returns the generated challenge to save for later validation
* @return ByteBuffer
*/
public function getChallenge() {
return $this->_challenge;
}
/**
* generates the object for a key registration
* provide this data to navigator.credentials.create
* @param string $userId
* @param string $userName
* @param string $userDisplayName
* @param int $timeout timeout in seconds
* @param bool $requireResidentKey true, if the key should be stored by the authentication device
* @param bool|string $requireUserVerification indicates that you require user verification and will fail the operation
* if the response does not have the UV flag set.
* Valid values:
* true = required
* false = preferred
* string 'required' 'preferred' 'discouraged'
* @param bool|null $crossPlatformAttachment true for cross-platform devices (eg. fido usb),
* false for platform devices (eg. windows hello, android safetynet),
* null for both
* @param array $excludeCredentialIds a array of ids, which are already registered, to prevent re-registration
* @return \stdClass
*/
public function getCreateArgs($userId, $userName, $userDisplayName, $timeout=20, $requireResidentKey=false, $requireUserVerification=false, $crossPlatformAttachment=null, $excludeCredentialIds=array()) {
// validate User Verification Requirement
if (\is_bool($requireUserVerification)) {
$requireUserVerification = $requireUserVerification ? 'required' : 'preferred';
} else if (\is_string($requireUserVerification) && \in_array(\strtolower($requireUserVerification), ['required', 'preferred', 'discouraged'])) {
$requireUserVerification = \strtolower($requireUserVerification);
} else {
$requireUserVerification = 'preferred';
}
$args = new \stdClass();
$args->publicKey = new \stdClass();
// relying party
$args->publicKey->rp = new \stdClass();
$args->publicKey->rp->name = $this->_rpName;
$args->publicKey->rp->id = $this->_rpId;
$args->publicKey->authenticatorSelection = new \stdClass();
$args->publicKey->authenticatorSelection->userVerification = $requireUserVerification;
if ($requireResidentKey) {
$args->publicKey->authenticatorSelection->requireResidentKey = true;
}
if (is_bool($crossPlatformAttachment)) {
$args->publicKey->authenticatorSelection->authenticatorAttachment = $crossPlatformAttachment ? 'cross-platform' : 'platform';
}
// user
$args->publicKey->user = new \stdClass();
$args->publicKey->user->id = new ByteBuffer($userId); // binary
$args->publicKey->user->name = $userName;
$args->publicKey->user->displayName = $userDisplayName;
$args->publicKey->pubKeyCredParams = array();
$tmp = new \stdClass();
$tmp->type = 'public-key';
$tmp->alg = -7; // ES256
$args->publicKey->pubKeyCredParams[] = $tmp;
unset ($tmp);
$tmp = new \stdClass();
$tmp->type = 'public-key';
$tmp->alg = -257; // RS256
$args->publicKey->pubKeyCredParams[] = $tmp;
unset ($tmp);
// if there are root certificates added, we need direct attestation to validate
// against the root certificate. If there are no root-certificates added,
// anonymization ca are also accepted, because we can't validate the root anyway.
$attestation = 'indirect';
if (\is_array($this->_caFiles)) {
$attestation = 'direct';
}
$args->publicKey->attestation = \count($this->_formats) === 1 && \in_array('none', $this->_formats) ? 'none' : $attestation;
$args->publicKey->extensions = new \stdClass();
$args->publicKey->extensions->exts = true;
$args->publicKey->timeout = $timeout * 1000; // microseconds
$args->publicKey->challenge = $this->_createChallenge(); // binary
//prevent re-registration by specifying existing credentials
$args->publicKey->excludeCredentials = array();
if (is_array($excludeCredentialIds)) {
foreach ($excludeCredentialIds as $id) {
$tmp = new \stdClass();
$tmp->id = $id instanceof ByteBuffer ? $id : new ByteBuffer($id); // binary
$tmp->type = 'public-key';
$tmp->transports = array('usb', 'ble', 'nfc', 'internal');
$args->publicKey->excludeCredentials[] = $tmp;
unset ($tmp);
}
}
return $args;
}
/**
* generates the object for key validation
* Provide this data to navigator.credentials.get
* @param array $credentialIds binary
* @param int $timeout timeout in seconds
* @param bool $allowUsb allow removable USB
* @param bool $allowNfc allow Near Field Communication (NFC)
* @param bool $allowBle allow Bluetooth
* @param bool $allowInternal allow client device-specific transport. These authenticators are not removable from the client device.
* @param bool|string $requireUserVerification indicates that you require user verification and will fail the operation
* if the response does not have the UV flag set.
* Valid values:
* true = required
* false = preferred
* string 'required' 'preferred' 'discouraged'
* @return \stdClass
*/
public function getGetArgs($credentialIds=array(), $timeout=20, $allowUsb=true, $allowNfc=true, $allowBle=true, $allowInternal=true, $requireUserVerification=false) {
// validate User Verification Requirement
if (\is_bool($requireUserVerification)) {
$requireUserVerification = $requireUserVerification ? 'required' : 'preferred';
} else if (\is_string($requireUserVerification) && \in_array(\strtolower($requireUserVerification), ['required', 'preferred', 'discouraged'])) {
$requireUserVerification = \strtolower($requireUserVerification);
} else {
$requireUserVerification = 'preferred';
}
$args = new \stdClass();
$args->publicKey = new \stdClass();
$args->publicKey->timeout = $timeout * 1000; // microseconds
$args->publicKey->challenge = $this->_createChallenge(); // binary
$args->publicKey->userVerification = $requireUserVerification;
$args->publicKey->rpId = $this->_rpId;
if (\is_array($credentialIds) && \count($credentialIds) > 0) {
$args->publicKey->allowCredentials = array();
foreach ($credentialIds as $id) {
$tmp = new \stdClass();
$tmp->id = $id instanceof ByteBuffer ? $id : new ByteBuffer($id); // binary
$tmp->transports = array();
if ($allowUsb) {
$tmp->transports[] = 'usb';
}
if ($allowNfc) {
$tmp->transports[] = 'nfc';
}
if ($allowBle) {
$tmp->transports[] = 'ble';
}
if ($allowInternal) {
$tmp->transports[] = 'internal';
}
$tmp->type = 'public-key';
$args->publicKey->allowCredentials[] = $tmp;
unset ($tmp);
}
}
return $args;
}
/**
* returns the new signature counter value.
* returns null if there is no counter
* @return ?int
*/
public function getSignatureCounter() {
return \is_int($this->_signatureCounter) ? $this->_signatureCounter : null;
}
/**
* process a create request and returns data to save for future logins
* @param string $clientDataJSON binary from browser
* @param string $attestationObject binary from browser
* @param string|ByteBuffer $challenge binary used challange
* @param bool $requireUserVerification true, if the device must verify user (e.g. by biometric data or pin)
* @param bool $requireUserPresent false, if the device must NOT check user presence (e.g. by pressing a button)
* @param bool $failIfRootMismatch false, if there should be no error thrown if root certificate doesn't match
* @return \stdClass
* @throws WebAuthnException
*/
public function processCreate($clientDataJSON, $attestationObject, $challenge, $requireUserVerification=false, $requireUserPresent=true, $failIfRootMismatch=true) {
$clientDataHash = \hash('sha256', $clientDataJSON, true);
$clientData = \json_decode($clientDataJSON);
$challenge = $challenge instanceof ByteBuffer ? $challenge : new ByteBuffer($challenge);
// security: https://www.w3.org/TR/webauthn/#registering-a-new-credential
// 2. Let C, the client data claimed as collected during the credential creation,
// be the result of running an implementation-specific JSON parser on JSONtext.
if (!\is_object($clientData)) {
throw new WebAuthnException('invalid client data', WebAuthnException::INVALID_DATA);
}
// 3. Verify that the value of C.type is webauthn.create.
if (!\property_exists($clientData, 'type') || $clientData->type !== 'webauthn.create') {
throw new WebAuthnException('invalid type', WebAuthnException::INVALID_TYPE);
}
// 4. Verify that the value of C.challenge matches the challenge that was sent to the authenticator in the create() call.
if (!\property_exists($clientData, 'challenge') || ByteBuffer::fromBase64Url($clientData->challenge)->getBinaryString() !== $challenge->getBinaryString()) {
throw new WebAuthnException('invalid challenge', WebAuthnException::INVALID_CHALLENGE);
}
// 5. Verify that the value of C.origin matches the Relying Party's origin.
if (!\property_exists($clientData, 'origin') || !$this->_checkOrigin($clientData->origin)) {
throw new WebAuthnException('invalid origin', WebAuthnException::INVALID_ORIGIN);
}
// Attestation
$attestationObject = new Attestation\AttestationObject($attestationObject, $this->_formats);
// 9. Verify that the RP ID hash in authData is indeed the SHA-256 hash of the RP ID expected by the RP.
if (!$attestationObject->validateRpIdHash($this->_rpIdHash)) {
throw new WebAuthnException('invalid rpId hash', WebAuthnException::INVALID_RELYING_PARTY);
}
// 14. Verify that attStmt is a correct attestation statement, conveying a valid attestation signature
if (!$attestationObject->validateAttestation($clientDataHash)) {
throw new WebAuthnException('invalid certificate signature', WebAuthnException::INVALID_SIGNATURE);
}
// 15. If validation is successful, obtain a list of acceptable trust anchors
$rootValid = is_array($this->_caFiles) ? $attestationObject->validateRootCertificate($this->_caFiles) : null;
if ($failIfRootMismatch && is_array($this->_caFiles) && !$rootValid) {
throw new WebAuthnException('invalid root certificate', WebAuthnException::CERTIFICATE_NOT_TRUSTED);
}
// 10. Verify that the User Present bit of the flags in authData is set.
$userPresent = $attestationObject->getAuthenticatorData()->getUserPresent();
if ($requireUserPresent && !$userPresent) {
throw new WebAuthnException('user not present during authentication', WebAuthnException::USER_PRESENT);
}
// 11. If user verification is required for this registration, verify that the User Verified bit of the flags in authData is set.
$userVerified = $attestationObject->getAuthenticatorData()->getUserVerified();
if ($requireUserVerification && !$userVerified) {
throw new WebAuthnException('user not verified during authentication', WebAuthnException::USER_VERIFICATED);
}
$signCount = $attestationObject->getAuthenticatorData()->getSignCount();
if ($signCount > 0) {
$this->_signatureCounter = $signCount;
}
// prepare data to store for future logins
$data = new \stdClass();
$data->rpId = $this->_rpId;
$data->attestationFormat = $attestationObject->getAttestationFormatName();
$data->credentialId = $attestationObject->getAuthenticatorData()->getCredentialId();
$data->credentialPublicKey = $attestationObject->getAuthenticatorData()->getPublicKeyPem();
$data->certificateChain = $attestationObject->getCertificateChain();
$data->certificate = $attestationObject->getCertificatePem();
$data->certificateIssuer = $attestationObject->getCertificateIssuer();
$data->certificateSubject = $attestationObject->getCertificateSubject();
$data->signatureCounter = $this->_signatureCounter;
$data->AAGUID = $attestationObject->getAuthenticatorData()->getAAGUID();
$data->rootValid = $rootValid;
$data->userPresent = $userPresent;
$data->userVerified = $userVerified;
return $data;
}
/**
* process a get request
* @param string $clientDataJSON binary from browser
* @param string $authenticatorData binary from browser
* @param string $signature binary from browser
* @param string $credentialPublicKey string PEM-formated public key from used credentialId
* @param string|ByteBuffer $challenge binary from used challange
* @param int $prevSignatureCnt signature count value of the last login
* @param bool $requireUserVerification true, if the device must verify user (e.g. by biometric data or pin)
* @param bool $requireUserPresent true, if the device must check user presence (e.g. by pressing a button)
* @return boolean true if get is successful
* @throws WebAuthnException
*/
public function processGet($clientDataJSON, $authenticatorData, $signature, $credentialPublicKey, $challenge, $prevSignatureCnt=null, $requireUserVerification=false, $requireUserPresent=true) {
$authenticatorObj = new Attestation\AuthenticatorData($authenticatorData);
$clientDataHash = \hash('sha256', $clientDataJSON, true);
$clientData = \json_decode($clientDataJSON);
$challenge = $challenge instanceof ByteBuffer ? $challenge : new ByteBuffer($challenge);
// https://www.w3.org/TR/webauthn/#verifying-assertion
// 1. If the allowCredentials option was given when this authentication ceremony was initiated,
// verify that credential.id identifies one of the public key credentials that were listed in allowCredentials.
// -> TO BE VERIFIED BY IMPLEMENTATION
// 2. If credential.response.userHandle is present, verify that the user identified
// by this value is the owner of the public key credential identified by credential.id.
// -> TO BE VERIFIED BY IMPLEMENTATION
// 3. Using credentials id attribute (or the corresponding rawId, if base64url encoding is
// inappropriate for your use case), look up the corresponding credential public key.
// -> TO BE LOOKED UP BY IMPLEMENTATION
// 5. Let JSONtext be the result of running UTF-8 decode on the value of cData.
if (!\is_object($clientData)) {
throw new WebAuthnException('invalid client data', WebAuthnException::INVALID_DATA);
}
// 7. Verify that the value of C.type is the string webauthn.get.
if (!\property_exists($clientData, 'type') || $clientData->type !== 'webauthn.get') {
throw new WebAuthnException('invalid type', WebAuthnException::INVALID_TYPE);
}
// 8. Verify that the value of C.challenge matches the challenge that was sent to the
// authenticator in the PublicKeyCredentialRequestOptions passed to the get() call.
if (!\property_exists($clientData, 'challenge') || ByteBuffer::fromBase64Url($clientData->challenge)->getBinaryString() !== $challenge->getBinaryString()) {
throw new WebAuthnException('invalid challenge', WebAuthnException::INVALID_CHALLENGE);
}
// 9. Verify that the value of C.origin matches the Relying Party's origin.
if (!\property_exists($clientData, 'origin') || !$this->_checkOrigin($clientData->origin)) {
throw new WebAuthnException('invalid origin', WebAuthnException::INVALID_ORIGIN);
}
// 11. Verify that the rpIdHash in authData is the SHA-256 hash of the RP ID expected by the Relying Party.
if ($authenticatorObj->getRpIdHash() !== $this->_rpIdHash) {
throw new WebAuthnException('invalid rpId hash', WebAuthnException::INVALID_RELYING_PARTY);
}
// 12. Verify that the User Present bit of the flags in authData is set
if ($requireUserPresent && !$authenticatorObj->getUserPresent()) {
throw new WebAuthnException('user not present during authentication', WebAuthnException::USER_PRESENT);
}
// 13. If user verification is required for this assertion, verify that the User Verified bit of the flags in authData is set.
if ($requireUserVerification && !$authenticatorObj->getUserVerified()) {
throw new WebAuthnException('user not verificated during authentication', WebAuthnException::USER_VERIFICATED);
}
// 14. Verify the values of the client extension outputs
// (extensions not implemented)
// 16. Using the credential public key looked up in step 3, verify that sig is a valid signature
// over the binary concatenation of authData and hash.
$dataToVerify = '';
$dataToVerify .= $authenticatorData;
$dataToVerify .= $clientDataHash;
$publicKey = \openssl_pkey_get_public($credentialPublicKey);
if ($publicKey === false) {
throw new WebAuthnException('public key invalid', WebAuthnException::INVALID_PUBLIC_KEY);
}
if (\openssl_verify($dataToVerify, $signature, $publicKey, OPENSSL_ALGO_SHA256) !== 1) {
throw new WebAuthnException('invalid signature', WebAuthnException::INVALID_SIGNATURE);
}
// 17. If the signature counter value authData.signCount is nonzero,
// if less than or equal to the signature counter value stored,
// is a signal that the authenticator may be cloned
$signatureCounter = $authenticatorObj->getSignCount();
if ($signatureCounter > 0) {
$this->_signatureCounter = $signatureCounter;
if ($prevSignatureCnt !== null && $prevSignatureCnt >= $signatureCounter) {
throw new WebAuthnException('signature counter not valid', WebAuthnException::SIGNATURE_COUNTER);
}
}
return true;
}
/**
* Downloads root certificates from FIDO Alliance Metadata Service (MDS) to a specific folder
* https://fidoalliance.org/metadata/
* @param string $certFolder Folder path to save the certificates in PEM format.
* @param bool $deleteCerts=true
* @return int number of cetificates
* @throws WebAuthnException
*/
public function queryFidoMetaDataService($certFolder, $deleteCerts=true) {
$url = 'https://mds.fidoalliance.org/';
$raw = null;
if (\function_exists('curl_init')) {
$ch = \curl_init($url);
\curl_setopt($ch, CURLOPT_HEADER, false);
\curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
\curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
\curl_setopt($ch, CURLOPT_USERAGENT, 'github.com/lbuchs/WebAuthn - A simple PHP WebAuthn server library');
$raw = \curl_exec($ch);
\curl_close($ch);
} else {
$raw = \file_get_contents($url);
}
$certFolder = \rtrim(\realpath($certFolder), '\\/');
if (!is_dir($certFolder)) {
throw new WebAuthnException('Invalid folder path for query FIDO Alliance Metadata Service');
}
if (!\is_string($raw)) {
throw new WebAuthnException('Unable to query FIDO Alliance Metadata Service');
}
$jwt = \explode('.', $raw);
if (\count($jwt) !== 3) {
throw new WebAuthnException('Invalid JWT from FIDO Alliance Metadata Service');
}
if ($deleteCerts) {
foreach (\scandir($certFolder) as $ca) {
if (\substr($ca, -4) === '.pem') {
if (\unlink($certFolder . DIRECTORY_SEPARATOR . $ca) === false) {
throw new WebAuthnException('Cannot delete certs in folder for FIDO Alliance Metadata Service');
}
}
}
}
list($header, $payload, $hash) = $jwt;
$payload = Binary\ByteBuffer::fromBase64Url($payload)->getJson();
$count = 0;
if (\is_object($payload) && \property_exists($payload, 'entries') && \is_array($payload->entries)) {
foreach ($payload->entries as $entry) {
if (\is_object($entry) && \property_exists($entry, 'metadataStatement') && \is_object($entry->metadataStatement)) {
$description = $entry->metadataStatement->description ?? null;
$attestationRootCertificates = $entry->metadataStatement->attestationRootCertificates ?? null;
if ($description && $attestationRootCertificates) {
// create filename
$certFilename = \preg_replace('/[^a-z0-9]/i', '_', $description);
$certFilename = \trim(\preg_replace('/\_{2,}/i', '_', $certFilename),'_') . '.pem';
$certFilename = \strtolower($certFilename);
// add certificate
$certContent = $description . "\n";
$certContent .= \str_repeat('-', \mb_strlen($description)) . "\n";
foreach ($attestationRootCertificates as $attestationRootCertificate) {
$count++;
$certContent .= "\n-----BEGIN CERTIFICATE-----\n";
$certContent .= \chunk_split(\trim($attestationRootCertificate), 64, "\n");
$certContent .= "-----END CERTIFICATE-----\n";
}
if (\file_put_contents($certFolder . DIRECTORY_SEPARATOR . $certFilename, $certContent) === false) {
throw new WebAuthnException('unable to save certificate from FIDO Alliance Metadata Service');
}
}
}
}
}
return $count;
}
// -----------------------------------------------
// PRIVATE
// -----------------------------------------------
/**
* checks if the origin matchs the RP ID
* @param string $origin
* @return boolean
* @throws WebAuthnException
*/
private function _checkOrigin($origin) {
// https://www.w3.org/TR/webauthn/#rp-id
// The origin's scheme must be https
if ($this->_rpId !== 'localhost' && \parse_url($origin, PHP_URL_SCHEME) !== 'https') {
return false;
}
// extract host from origin
$host = \parse_url($origin, PHP_URL_HOST);
$host = \trim($host, '.');
// The RP ID must be equal to the origin's effective domain, or a registrable
// domain suffix of the origin's effective domain.
return \preg_match('/' . \preg_quote($this->_rpId) . '$/i', $host) === 1;
}
/**
* generates a new challange
* @param int $length
* @return string
* @throws WebAuthnException
*/
private function _createChallenge($length = 32) {
if (!$this->_challenge) {
$this->_challenge = ByteBuffer::randomBuffer($length);
}
return $this->_challenge;
}
}