How to set HTTPS SSL Cipher Suite Preference in Spring boot embedded tomcat

Question

I trying to set HTTPS SSL cipher suite preference according to server preference rather than auto select based on client & server supported common cipher suite with highest strength.

I like to let server choose for common between server & client having "TLS_ECDHE..." in order to support Forward Secrecy. Now I tested in "www.ssllabs.com", client browser will prefer cipher having "TLS_RSA..." rather than "TLS_ECDHE"...

I noticed java 8 support set cipher suite preference: http://docs.oracle.com/javase/8/docs/technotes/guides/security/jsse/JSSERefGuide.html#cipher_suite_preference

I assume spring boot embedded Tomcat will call Java 8 function to choose cipher

Here is what I done in spring boot application.properties file to set server support ciphers set:

server.ssl.ciphers=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,TLS_DHE_RSA_WITH_AES_128_GCM_SHA256,TLS_DHE_DSS_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_128_SHA256,TLS_ECDHE_ECDSA_WITH_AES_128_SHA256,TLS_ECDHE_RSA_WITH_AES_128_SHA,TLS_ECDHE_ECDSA_WITH_AES_128_SHA,TLS_ECDHE_RSA_WITH_AES_256_SHA384,TLS_ECDHE_ECDSA_WITH_AES_256_SHA384,TLS_ECDHE_RSA_WITH_AES_256_SHA,TLS_ECDHE_ECDSA_WITH_AES_256_SHA,TLS_DHE_RSA_WITH_AES_128_SHA256,TLS_DHE_RSA_WITH_AES_128_SHA,TLS_DHE_DSS_WITH_AES_128_SHA256,TLS_DHE_RSA_WITH_AES_256_SHA256,TLS_DHE_DSS_WITH_AES_256_SHA,TLS_DHE_RSA_WITH_AES_256_SHA

Hopefully someone can guide me how to override default choose cipher behaviour.

Answer 1

You need to tell the connector's underlying protocol handler to use the server's cipher suite order. You can do so with a WebServerFactoryCustomizer :

@Bean
public WebServerFactoryCustomizer<TomcatServletWebServerFactory> servletContainerCustomizer() {
    return (factory) -> {
        factory.addConnectorCustomizers((c) -> 
            ((AbstractHttp11Protocol<?>) c.getProtocolHandler()).setUseServerCipherSuitesOrder(true));
    };
}