Step1: Put your security certificate inside raw directory like src/main/res/raw/client_certificate.cer
Step2: Create a SSLContext object with this certificate like
SSLContext sslContext = createCertificate(getApplicationContext().getResources().openRawResource(R.raw.client_certificate));
Step3: Add the created SSLContext object to your OkHttpClient builder.
addClientCertificate(okHttpClientBuilder);
Step4: Set the OkHttpClient builder to retrofit client like.
retrofitBuilder.client(okHttpClientBuilder.build());
Here is complete implementation for all above mentioned steps in RetrofitManager.java file.
RetrofitManager.java
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.security.KeyManagementException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.concurrent.TimeUnit;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;
import java.security.cert.Certificate;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.logging.HttpLoggingInterceptor;
import retrofit2.Retrofit;
import retrofit2.adapter.rxjava.RxJavaCallAdapterFactory;
import retrofit2.converter.gson.GsonConverterFactory;
/**
* Created by Rajoo Kannaujiya on 02/16/2020.
*/
public class RetrofitManager {
private static final String URL = "https://stackoverflow.com"; // Fetch url from config file.
private static final String TLS = "TLS";
private static final String SSL = "SSL";
private static final String CA = "ca";
private static final String X_509 = "X.509";
private static final String PROD = "prod";
private static X509TrustManager trustManager = null;
private static final String CONTENT_TYPE = "Content-Type";
private static final String CONTENT_TYPE_VALUE = "application/json";
public static final String BUILD_TYPE = "prod"; // Fetch build type from config file (Whether it is a dev, qa, stage or prod build).
public static Retrofit getRetrofitForAPIUrl() {
return getRetrofit(URL);
}
private static Retrofit getRetrofit(String url) {
Gson gson = new GsonBuilder().setLenient().create();
Retrofit.Builder retrofitBuilder = new Retrofit.Builder()
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())
.addConverterFactory(GsonConverterFactory.create(gson))
.baseUrl(url);
HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
logging.level(HttpLoggingInterceptor.Level.BODY);
OkHttpClient.Builder okHttpClientBuilder = new OkHttpClient.Builder();
okHttpClientBuilder.addInterceptor(chain -> {
Request origReq = chain.request();
Request.Builder requestBuilder = origReq.newBuilder()
.addHeader(CONTENT_TYPE, CONTENT_TYPE_VALUE);
Request request = requestBuilder.build();
return chain.proceed(request);
});
addClientCertificate(okHttpClientBuilder);
OkHttpClient.Builder okHttpBuilder = okHttpClientBuilder
.connectTimeout(10, TimeUnit.SECONDS)
.writeTimeout(20, TimeUnit.SECONDS)
.readTimeout(30, TimeUnit.SECONDS)
.addInterceptor(logging);
retrofitBuilder.client(okHttpBuilder.build());
return retrofitBuilder.build();
}
/**
* Method to create SSLContext object for the client certificate and return it.
*
* @param clientCertificate
* @return SSLContext Object
*/
private static SSLContext getSSLContextForClientCertificate(InputStream clientCertificate) {
SSLContext sslContext = null;
// If given client certificate is for production environment only, Then check put check for build type.
if (PROD.contentEquals(BUILD_TYPE)) {
// Creating X.509 certificate factory instance
CertificateFactory cf = null;
try {
cf = CertificateFactory.getInstance(X_509);
} catch (CertificateException e) {
e.printStackTrace();
}
// Generating client certificate
Certificate ca = null;
try {
try {
if (cf != null) {
ca = cf.generateCertificate(clientCertificate);
}
} catch (CertificateException e) {
e.printStackTrace();
}
} finally {
try {
clientCertificate.close();
} catch (IOException e) {
e.printStackTrace();
}
}
// Creating a KeyStore containing our trusted CAs
String keyStoreType = KeyStore.getDefaultType();
KeyStore keyStore = null;
try {
keyStore = KeyStore.getInstance(keyStoreType);
} catch (KeyStoreException e) {
e.printStackTrace();
}
if (keyStore != null) {
try {
keyStore.load(null, null);
} catch (CertificateException | IOException | NoSuchAlgorithmException e) {
e.printStackTrace();
}
try {
keyStore.setCertificateEntry(CA, ca);
} catch (KeyStoreException e) {
e.printStackTrace();
}
}
// Creating a TrustManager that trusts the CAs in our KeyStore
String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
TrustManagerFactory tmf = null;
try {
tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
try {
if (tmf != null) {
tmf.init(keyStore);
}
} catch (KeyStoreException e) {
e.printStackTrace();
}
// Creating an SSLContext instance that uses our TrustManager
try {
sslContext = SSLContext.getInstance(TLS);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
try {
if (sslContext != null && tmf != null) {
sslContext.init(null, tmf.getTrustManagers(), null);
}
} catch (KeyManagementException e) {
e.printStackTrace();
}
} else { // For non prod environment build. This section is useful only if you don't have client certificate for lower environment.
try {
sslContext = SSLContext.getInstance(SSL);
sslContext.init(null, new TrustManager[]{getTrustManager()}, new java.security.SecureRandom());
} catch (NoSuchAlgorithmException | KeyManagementException e) {
e.printStackTrace();
}
}
trustManager = getTrustManager();
return sslContext;
}
/**
* Method to add client certificate to OkHttpClient.Builder object.
*
* @param okHttpClientBuilder
* @return void
*/
private static void addClientCertificate(OkHttpClient.Builder okHttpClientBuilder) {
SSLContext sslContext = getSSLContextForClientCertificate(getApplicationContext().getResources().openRawResource(R.raw.myaccount_coxbusiness_com));
if (sslContext != null) {
okHttpClientBuilder.sslSocketFactory(sslContext.getSocketFactory(), trustManager);
okHttpClientBuilder.hostnameVerifier((hostname, session) -> true);
}
}
private static X509TrustManager getTrustManager() {
X509TrustManager trustManager = null;
if (PROD.contentEquals(BUILD_TYPE)) { // If client certificate is only available for prod environment.
try {
TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
trustManagerFactory.init((KeyStore) null);
TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();
if (trustManagers[0] instanceof X509TrustManager) {
trustManager = (X509TrustManager) trustManagers[0];
}
} catch (GeneralSecurityException e) {
throw new AssertionError();
}
} else { // For non prod environment build. This section is useful only if you don't have client certificate for lower environment.
trustManager = new X509TrustManager() {
@Override
public void checkClientTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {
}
@Override
public void checkServerTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {
}
@Override
public X509Certificate[] getAcceptedIssuers() {
return new X509Certificate[0];
}
};
}
return trustManager;
}
}
