Verify Certificate and Hostname for an HTTPS REST call with Spring RestTemplate

Question

I have a Spring Boot Microservice where I am trying to invoke an external server which exposes an HTTPS REST Endpoint (TLS v1.2). I have been provided the server side certificate in .pem format.

I would like to implement this call using RestTemplate and use the provided certificate and verify the host name during the call.

I have tried to Google this and all the search results are trying to ignore the certificate and host name.

Can I have an example code snippet to implement this properly?

Answer 1

After some digging with different blogs and stackoverflow threads, following worked for me:

Create Rest Template:

KeyStore keyStore = KeyStore.getInstance("PKCS12");
keyStore.load(new FileInputStream(ResourceUtils.getFile(clientKeyPath)), "".toCharArray());

SSLContext sslContext = SSLContextBuilder
                .create()
                .loadKeyMaterial(keyStore, null)
                .loadTrustMaterial(ResourceUtils.getFile(keystorePath), keystorePassword.toCharArray())
                .build();

SSLConnectionSocketFactory sslConnectionSocketFactory = new  SSLConnectionSocketFactory(sslContext, new CustomHostnameVerifier());

HttpClient client = HttpClients
                .custom()
                .setSSLSocketFactory(sslConnectionSocketFactory)
                .build();

HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();

requestFactory.setHttpClient(client);

RestTemplate sslRestTemplate = new RestTemplate(requestFactory);

Implementation of CustomHostnameVerifier:

@Component
public class CustomHostnameVerifier implements HostnameVerifier {

    @Value("${dns.name}")
    private String dnsName;

    @Override
    public boolean verify(String hostname, SSLSession session) {
        return hostname.equals(dnsName);
    }
}