You need to fulfill a couple of steps. Firstly change login configuration:

Edit config file located here: exo-jetty/webapps/rest.war/WEB-INF/web.xml

Replace

<login-config>                                                                                                                                          
  <auth-method>BASIC</auth-method>                                                                                                                     
  <realm-name>eXo REST services</realm-name>                                                                                                           
</login-config>

for

<login-config>                                                                                                                                          
  <auth-method>DIGEST</auth-method>                                                                                                                     
  <realm-name>eXo REST services</realm-name>                                                                                                           
</login-config>

Secondly you also need to specify new login module for JAAS:

Edit config file located here: exo-jetty/jaas.conf

Replace

exo-domain {
  org.exoplatform.services.security.j2ee.JettyLoginModule required;
};

for

exo-domain {
  org.exoplatform.services.security.j2ee.DigestAuthenticationJettyLoginModule required;
};