Ignoring SSL certificate in Apache HttpClient 4.3

The code below works for trusting self-signed certificates. You have to use the TrustSelfSignedStrategy when creating your client:

SSLContextBuilder builder = new SSLContextBuilder();
builder.loadTrustMaterial(null, new TrustSelfSignedStrategy());
SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
        builder.build());
CloseableHttpClient httpclient = HttpClients.custom().setSSLSocketFactory(
        sslsf).build();

HttpGet httpGet = new HttpGet("https://some-server");
CloseableHttpResponse response = httpclient.execute(httpGet);
try {
    System.out.println(response.getStatusLine());
    HttpEntity entity = response.getEntity();
    EntityUtils.consume(entity);
} finally {
    response.close();
}

I did not include the SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER on purpose: The point was to allow testing with self signed certificates so you don't have to acquire a proper certificate from a certification authority. You can easily create a self-signed certificate with the correct host name, so do that instead of adding the SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER flag.

If you are using PoolingHttpClientConnectionManager procedure above doesn't work, custom SSLContext is ignored. You have to pass socketFactoryRegistry in contructor when creating PoolingHttpClientConnectionManager.

SSLContextBuilder builder = SSLContexts.custom();
builder.loadTrustMaterial(null, new TrustStrategy() {
    @Override
    public boolean isTrusted(X509Certificate[] chain, String authType)
            throws CertificateException {
        return true;
    }
});
SSLContext sslContext = builder.build();
SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
        sslContext, new X509HostnameVerifier() {
            @Override
            public void verify(String host, SSLSocket ssl)
                    throws IOException {
            }

            @Override
            public void verify(String host, X509Certificate cert)
                    throws SSLException {
            }

            @Override
            public void verify(String host, String[] cns,
                    String[] subjectAlts) throws SSLException {
            }

            @Override
            public boolean verify(String s, SSLSession sslSession) {
                return true;
            }
        });

Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder
        .<ConnectionSocketFactory> create().register("https", sslsf)
        .build();

PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager(
        socketFactoryRegistry);
CloseableHttpClient httpclient = HttpClients.custom()
        .setConnectionManager(cm).build();

As an addition to the answer of @mavroprovato, if you want to trust all certificates instead of just self-signed, you'd do (in the style of your code)

builder.loadTrustMaterial(null, new TrustStrategy(){
    public boolean isTrusted(X509Certificate[] chain, String authType)
        throws CertificateException {
        return true;
    }
});

or (direct copy-paste from my own code):

import javax.net.ssl.SSLContext;
import org.apache.http.ssl.TrustStrategy;
import org.apache.http.ssl.SSLContexts;

// ...

        SSLContext sslContext = SSLContexts
                .custom()
                //FIXME to contain real trust store
                .loadTrustMaterial(new TrustStrategy() {
                    @Override
                    public boolean isTrusted(X509Certificate[] chain,
                        String authType) throws CertificateException {
                        return true;
                    }
                })
                .build();

And if you want to skip hostname verification as well, you need to set

    CloseableHttpClient httpclient = HttpClients.custom().setSSLSocketFactory(
            sslsf).setSSLHostnameVerifier( NoopHostnameVerifier.INSTANCE).build();

as well. (ALLOW_ALL_HOSTNAME_VERIFIER is deprecated).

Obligatory warning: you shouldn't really do this, accepting all certificates is a bad thing. However there are some rare use cases where you want to do this.

As a note to code previously given, you'll want to close response even if httpclient.execute() throws an exception

CloseableHttpResponse response = null;
try {
    response = httpclient.execute(httpGet);
    System.out.println(response.getStatusLine());
    HttpEntity entity = response.getEntity();
    EntityUtils.consume(entity);
}
finally {
    if (response != null) {
        response.close();
    }
}

Code above was tested using

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.3</version>
</dependency>

And for the interested, here's my full test set:

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.conn.ssl.NoopHostnameVerifier;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.TrustSelfSignedStrategy;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.ssl.SSLContextBuilder;
import org.apache.http.ssl.TrustStrategy;
import org.apache.http.util.EntityUtils;
import org.junit.Test;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLHandshakeException;
import javax.net.ssl.SSLPeerUnverifiedException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

public class TrustAllCertificatesTest {
    final String expiredCertSite = "https://expired.badssl.com/";
    final String selfSignedCertSite = "https://self-signed.badssl.com/";
    final String wrongHostCertSite = "https://wrong.host.badssl.com/";

    static final TrustStrategy trustSelfSignedStrategy = new TrustSelfSignedStrategy();
    static final TrustStrategy trustAllStrategy = new TrustStrategy(){
        public boolean isTrusted(X509Certificate[] chain, String authType)
                throws CertificateException {
            return true;
        }
    };

    @Test
    public void testSelfSignedOnSelfSignedUsingCode() throws Exception {
        doGet(selfSignedCertSite, trustSelfSignedStrategy);
    }
    @Test(expected = SSLHandshakeException.class)
    public void testExpiredOnSelfSignedUsingCode() throws Exception {
        doGet(expiredCertSite, trustSelfSignedStrategy);
    }
    @Test(expected = SSLPeerUnverifiedException.class)
    public void testWrongHostOnSelfSignedUsingCode() throws Exception {
        doGet(wrongHostCertSite, trustSelfSignedStrategy);
    }

    @Test
    public void testSelfSignedOnTrustAllUsingCode() throws Exception {
        doGet(selfSignedCertSite, trustAllStrategy);
    }
    @Test
    public void testExpiredOnTrustAllUsingCode() throws Exception {
        doGet(expiredCertSite, trustAllStrategy);
    }
    @Test(expected = SSLPeerUnverifiedException.class)
    public void testWrongHostOnTrustAllUsingCode() throws Exception {
        doGet(wrongHostCertSite, trustAllStrategy);
    }

    @Test
    public void testSelfSignedOnAllowAllUsingCode() throws Exception {
        doGet(selfSignedCertSite, trustAllStrategy, NoopHostnameVerifier.INSTANCE);
    }
    @Test
    public void testExpiredOnAllowAllUsingCode() throws Exception {
        doGet(expiredCertSite, trustAllStrategy, NoopHostnameVerifier.INSTANCE);
    }
    @Test
    public void testWrongHostOnAllowAllUsingCode() throws Exception {
        doGet(expiredCertSite, trustAllStrategy, NoopHostnameVerifier.INSTANCE);
    }

    public void doGet(String url, TrustStrategy trustStrategy, HostnameVerifier hostnameVerifier) throws Exception {
        SSLContextBuilder builder = new SSLContextBuilder();
        builder.loadTrustMaterial(trustStrategy);
        SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
                builder.build());
        CloseableHttpClient httpclient = HttpClients.custom().setSSLSocketFactory(
                sslsf).setSSLHostnameVerifier(hostnameVerifier).build();

        HttpGet httpGet = new HttpGet(url);
        CloseableHttpResponse response = httpclient.execute(httpGet);
        try {
            System.out.println(response.getStatusLine());
            HttpEntity entity = response.getEntity();
            EntityUtils.consume(entity);
        } finally {
            response.close();
        }
    }
    public void doGet(String url, TrustStrategy trustStrategy) throws Exception {

        SSLContextBuilder builder = new SSLContextBuilder();
        builder.loadTrustMaterial(trustStrategy);
        SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
                builder.build());
        CloseableHttpClient httpclient = HttpClients.custom().setSSLSocketFactory(
                sslsf).build();

        HttpGet httpGet = new HttpGet(url);
        CloseableHttpResponse response = httpclient.execute(httpGet);
        try {
            System.out.println(response.getStatusLine());
            HttpEntity entity = response.getEntity();
            EntityUtils.consume(entity);
        } finally {
            response.close();
        }
    }
}

(working test project in github)