火力基地|使用第三方 JWT 库验证 ID 令牌

Question

尝试使用 jjwt 验证 firebase id 令牌。使用 GoogleCredential 类提取私钥。但我不确定这是否正确。收到错误：JWT signature does not match locally computed signature.我应该在此处使用服务帐户 json 中的私钥吗？也许我误解了 ...setSigningKey(...) 的含义。

@Service
public class FirebaseAuthVerifier implements AuthVerifier {

    private static final Logger logger = LoggerFactory.getLogger(FirebaseAuthVerifier.class);

    @Autowired
    private FirebaseProperties fbProps;

    public boolean verify(AuthToken token) throws GeneralSecurityException, IOException {
        // get google credential
        InputStream stream = new FileInputStream("src/main/resources/service-account.json");
        ByteArrayOutputStream streamCopy = new ByteArrayOutputStream();
        ByteStreams.copy(stream, streamCopy);
        stream.close();

        GoogleCredential gc = GoogleCredential.fromStream(
                new ByteArrayInputStream(streamCopy.toByteArray()),
                new NetHttpTransport(),
                GsonFactory.getDefaultInstance());

        try {
            Jwts.parser().setSigningKey(gc.getServiceAccountPrivateKey()).parse(token.getTokenId());
        } catch(Exception e) {
            // log
            logger.info("Firebase auth token verification error: ");
            logger.info(e.getMessage());
            // claims may have been tampered with
            return false;
        }

        return true;
    }

}

Answer 1

你在正确的路线上！创建 JWT 以发送到 Google/Firebase 时会使用服务帐户中的密钥。你真的不想把它放在你的 APK 中，因为任何恶意的人都可以窃取它并像你一样使用它来创建 ID 令牌！

当您从 Firebase 验证令牌时，您需要检查 Firebase 自己的密钥 - 幸运的是，这些密钥是公开的！您可以从https://www.googleapis.com/robot/v1/metadata/x509/securetoken@system.gserviceaccount.com 获取它们 - 它们每隔几个小时轮换一次。如果您查看该文件，您会看到它是一个 JSON 字典，如下所示：

"8226146523a1b8894ba03ad525667b9475d393f5": "---CERT---",

其中的密钥是 ID 令牌 JWT 标头中的 kid 字段 - 它对应于签署令牌的密钥，这意味着对应的证书可用于验证签名。

查看validating ID tokens 的（服务器端）文档了解更多信息。

Answer 2

使用自定义 jwt id 令牌验证

@Service
public class FirebaseAuthVerifier implements AuthVerifier {

    private static final Logger logger = LoggerFactory.getLogger(FirebaseAuthVerifier.class);
    private static final String pubKeyUrl = "https://www.googleapis.com/robot/v1/metadata/x509/securetoken@system.gserviceaccount.com";

    /**
     *
     * @param token
     * @return
     * @throws GeneralSecurityException
     * @throws IOException
     */
    public boolean verify(AuthToken token) throws GeneralSecurityException, IOException {
        // get public keys
        JsonObject publicKeys = getPublicKeysJson();

        // verify count
        int size = publicKeys.entrySet().size();
        int count = 0;

        // get json object as map
        // loop map of keys finding one that verifies
        for (Map.Entry<String, JsonElement> entry: publicKeys.entrySet()) {
            // log
            logger.info("attempting jwt id token validation with: ");

            try {
                // trying next key
                count++;

                // get public key
                PublicKey publicKey = getPublicKey(entry);

                // validate claim set
                Jwts.parser().setSigningKey(publicKey).parse(token.getTokenId());

                // success, we can return
                return true;
            } catch(Exception e) {
                // log
                logger.info("Firebase id token verification error: ");
                logger.info(e.getMessage());
                // claims may have been tampered with
                // if this is the last key, return false
                if (count == size) {
                    return false;
                }
            }
        }

        // no jwt exceptions
        return true;
    }

    /**
     *
     * @param entry
     * @return
     * @throws GeneralSecurityException
     */
    private PublicKey getPublicKey(Map.Entry<String, JsonElement> entry) throws GeneralSecurityException, IOException {
        String publicKeyPem = entry.getValue().getAsString()
                .replaceAll("-----BEGIN (.*)-----", "")
                .replaceAll("-----END (.*)----", "")
                .replaceAll("\r\n", "")
                .replaceAll("\n", "")
                .trim();

        logger.info(publicKeyPem);

        // generate x509 cert
        InputStream inputStream = new ByteArrayInputStream(entry.getValue().getAsString().getBytes("UTF-8"));
        CertificateFactory cf = CertificateFactory.getInstance("X.509");
        X509Certificate cert = (X509Certificate)cf.generateCertificate(inputStream);

        return cert.getPublicKey();
    }

    /**
     *
     * @return
     * @throws IOException
     */
    private JsonObject getPublicKeysJson() throws IOException {
        // get public keys
        URI uri = URI.create(pubKeyUrl);
        GenericUrl url = new GenericUrl(uri);
        HttpTransport http = new NetHttpTransport();
        HttpResponse response = http.createRequestFactory().buildGetRequest(url).execute();

        // store json from request
        String json = response.parseAsString();
        // disconnect
        response.disconnect();

        // parse json to object
        JsonObject jsonObject = new JsonParser().parse(json).getAsJsonObject();

        return jsonObject;
    }

}