android - 如果证书是从特定的自签名 CA 签名的，请检查 WebViewClient 的 onReceivedSslError() 方法

Question

我想覆盖 WebViewClient 的 onReceivedSslError()。在这里，我想检查 error.getCertificate() 证书是否由自签名 CA 签署，仅在这种情况下，调用 handler.proceed ()。在伪代码中:

@Override
public void onReceivedSslError(WebView view, SslErrorHandler handler, SslError error) {
    SslCertificate serverCertificate = error.getCertificate();

    if (/* signed from my self-signed CA */) {
        handler.proceed();
    }
    else {
        super.onReceivedSslError(view, handler, error);
    }
}

我的 CA 的公钥保存在名为 rootca.bks 的 BouncyCaSTLe 资源中。我该怎么办？

Answer 1

我想你可以尝试如下:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    try {
        WebView webView = (WebView) findViewById(R.id.webView);
        if (webView != null) {
            // Get cert from raw resource...
            CertificateFactory cf = CertificateFactory.getInstance("X.509");
            InputStream caInput = getResources().openRawResource(R.raw.rootca); // stored at \app\src\main\res\raw
            final Certificate certificate = cf.generateCertificate(caInput);
            caInput.close();

            String url = "https://www.yourserver.com";
            webView.setWebViewClient(new WebViewClient() {                    
                @Override
                public void onReceivedSslError(WebView view, SslErrorHandler handler, SslError error) {
                    // Get cert from SslError
                    SslCertificate sslCertificate = error.getCertificate();
                    Certificate cert = getX509Certificate(sslCertificate);
                    if (cert != null && certificate != null){
                        try {
                            // Reference: https://developer.android.com/reference/java/security/cert/Certificate.html#verify(java.security.PublicKey)
                            cert.verify(certificate.getPublicKey()); // Verify here...
                            handler.proceed();
                        } catch (CertificateException | NoSuchAlgorithmException | InvalidKeyException | NoSuchProviderException | SignatureException e) {
                            super.onReceivedSslError(view, handler, error);
                            e.printStackTrace();
                        }
                    } else {
                        super.onReceivedSslError(view, handler, error);
                    }
                }
            });

            webView.loadUrl(url);
        }
    } catch (Exception e){
        e.printStackTrace();
    }
}

// credits to @Heath Borders at http://stackoverflow.com/questions/20228800/how-do-i-validate-an-android-net-http-sslcertificate-with-an-x509trustmanager
private Certificate getX509Certificate(SslCertificate sslCertificate){
    Bundle bundle = SslCertificate.saveState(sslCertificate);
    byte[] bytes = bundle.getByteArray("x509-certificate");
    if (bytes == null) {
        return null;
    } else {
        try {
            CertificateFactory certFactory = CertificateFactory.getInstance("X.509");
            return certFactory.generateCertificate(new ByteArrayInputStream(bytes));
        } catch (CertificateException e) {
            return null;
        }
    }
}

如果验证失败，logcat 将有一些信息，例如 java.security.SignatureException: Signature was not verified...

如果成功，截图如下: