Viewing file:  FidoU2FAttestationStatementSupport.php (4.89 KB) -rwxr-x---
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<?php
declare(strict_types=1);
/*
* The MIT License (MIT)
*
* Copyright (c) 2014-2021 Spomky-Labs
*
* This software may be modified and distributed under the terms
* of the MIT license. See the LICENSE file for details.
*/
namespace Webauthn\AttestationStatement;
use Assert\Assertion;
use CBOR\Decoder;
use CBOR\MapObject;
use CBOR\OtherObject\OtherObjectManager;
use CBOR\Tag\TagObjectManager;
use Cose\Key\Ec2Key;
use InvalidArgumentException;
use function Safe\openssl_pkey_get_public;
use function Safe\sprintf;
use Throwable;
use Webauthn\AuthenticatorData;
use Webauthn\CertificateToolbox;
use Webauthn\StringStream;
use Webauthn\TrustPath\CertificateTrustPath;
final class FidoU2FAttestationStatementSupport implements AttestationStatementSupport
{
/**
* @var Decoder
*/
private $decoder;
public function __construct()
{
$this->decoder = new Decoder(new TagObjectManager(), new OtherObjectManager());
}
public function name(): string
{
return 'fido-u2f';
}
/**
* @param mixed[] $attestation
*/
public function load(array $attestation): AttestationStatement
{
Assertion::keyExists($attestation, 'attStmt', 'Invalid attestation object');
foreach (['sig', 'x5c'] as $key) {
Assertion::keyExists($attestation['attStmt'], $key, sprintf('The attestation statement value "%s" is missing.', $key));
}
$certificates = $attestation['attStmt']['x5c'];
Assertion::isArray($certificates, 'The attestation statement value "x5c" must be a list with one certificate.');
Assertion::count($certificates, 1, 'The attestation statement value "x5c" must be a list with one certificate.');
Assertion::allString($certificates, 'The attestation statement value "x5c" must be a list with one certificate.');
reset($certificates);
$certificates = CertificateToolbox::convertAllDERToPEM($certificates);
$this->checkCertificate($certificates[0]);
return AttestationStatement::createBasic($attestation['fmt'], $attestation['attStmt'], new CertificateTrustPath($certificates));
}
public function isValid(string $clientDataJSONHash, AttestationStatement $attestationStatement, AuthenticatorData $authenticatorData): bool
{
Assertion::eq(
$authenticatorData->getAttestedCredentialData()->getAaguid()->toString(),
'00000000-0000-0000-0000-000000000000',
'Invalid AAGUID for fido-u2f attestation statement. Shall be "00000000-0000-0000-0000-000000000000"'
);
$trustPath = $attestationStatement->getTrustPath();
Assertion::isInstanceOf($trustPath, CertificateTrustPath::class, 'Invalid trust path');
$dataToVerify = "\0";
$dataToVerify .= $authenticatorData->getRpIdHash();
$dataToVerify .= $clientDataJSONHash;
$dataToVerify .= $authenticatorData->getAttestedCredentialData()->getCredentialId();
$dataToVerify .= $this->extractPublicKey($authenticatorData->getAttestedCredentialData()->getCredentialPublicKey());
return 1 === openssl_verify($dataToVerify, $attestationStatement->get('sig'), $trustPath->getCertificates()[0], OPENSSL_ALGO_SHA256);
}
private function extractPublicKey(?string $publicKey): string
{
Assertion::notNull($publicKey, 'The attested credential data does not contain a valid public key.');
$publicKeyStream = new StringStream($publicKey);
$coseKey = $this->decoder->decode($publicKeyStream);
Assertion::true($publicKeyStream->isEOF(), 'Invalid public key. Presence of extra bytes.');
$publicKeyStream->close();
Assertion::isInstanceOf($coseKey, MapObject::class, 'The attested credential data does not contain a valid public key.');
$coseKey = $coseKey->getNormalizedData();
$ec2Key = new Ec2Key($coseKey + [Ec2Key::TYPE => 2, Ec2Key::DATA_CURVE => Ec2Key::CURVE_P256]);
return "\x04".$ec2Key->x().$ec2Key->y();
}
private function checkCertificate(string $publicKey): void
{
try {
$resource = openssl_pkey_get_public($publicKey);
$details = openssl_pkey_get_details($resource);
} catch (Throwable $throwable) {
throw new InvalidArgumentException('Invalid certificate or certificate chain', 0, $throwable);
}
Assertion::isArray($details, 'Invalid certificate or certificate chain');
Assertion::keyExists($details, 'ec', 'Invalid certificate or certificate chain');
Assertion::keyExists($details['ec'], 'curve_name', 'Invalid certificate or certificate chain');
Assertion::eq($details['ec']['curve_name'], 'prime256v1', 'Invalid certificate or certificate chain');
Assertion::keyExists($details['ec'], 'curve_oid', 'Invalid certificate or certificate chain');
Assertion::eq($details['ec']['curve_oid'], '1.2.840.10045.3.1.7', 'Invalid certificate or certificate chain');
}
}
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