How to fix unsafe implementation of X509TrustManager in Android app

Question

Google has advised that I have an unsafe implementation of the interface X509TrustManager in my Android application and need to change my code as follows:

To properly handle SSL certificate validation, change your code in the checkServerTrusted method of your custom X509TrustManager interface to raise either CertificateException or IllegalArgumentException whenever the certificate presented by the server does not meet your expectations. For technical questions, you can post to Stack Overflow and use the tags “android-security” and “TrustManager.”

How can the following code be modified to fix the above issue?

public EasySSLSocketFactory(KeyStore truststore) throws NoSuchAlgorithmException, KeyManagementException, KeyStoreException, UnrecoverableKeyException {
    super(truststore);

    TrustManager tm = new X509TrustManager()  {
        public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
        }

        public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
        }

        public X509Certificate[] getAcceptedIssuers() {
            return null;
        }
    };

    mContext.init(null, new TrustManager[] { tm }, null);
}

Answer 1

I have solved this using the following code:

public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
                try {
                    chain[0].checkValidity();
                } catch (Exception e) {
                    throw new CertificateException("Certificate not valid or trusted.");
                }
            }