SPRING IN ACTION 第4版笔记-第九章Securing web applications-006-用LDAP比较密码(passwordCompare()、passwordAttribute("passcode")、passwordEncoder(new Md5PasswordEncoder()))

一、

The default strategy for authenticating against LDAP is to perform a bind operation,authenticating the user directly to the LDAP server. Another option is to perform a comparison operation. This involves sending the entered password to the LDAP directory and asking the server to compare the password against a user’s password attribute. Because the comparison is done within the LDAP server, the actual password remains secret.

If you’d rather authenticate by doing a password comparison, you can declare so with the passwordCompare() method:

 @Override
 protected void configure(AuthenticationManagerBuilder auth)
 throws Exception {
     auth
         .ldapAuthentication()
         .userSearchBase("ou=people")
         .userSearchFilter("(uid={0})")
         .groupSearchBase("ou=groups")
         .groupSearchFilter("member={0}")
         .passwordCompare();
 }

By default, the password given in the login form will be compared with the value of the userPassword attribute in the user’s LDAP entry. If the password is kept in a different attribute, you can specify the password attribute’s name with passwordAttribute() :

 @Override
 protected void configure(AuthenticationManagerBuilder auth)
 throws Exception {
     auth
         .ldapAuthentication()
         .userSearchBase("ou=people")
         .userSearchFilter("(uid={0})")
         .groupSearchBase("ou=groups")
         .groupSearchFilter("member={0}")
         .passwordCompare()
         .passwordEncoder(new Md5PasswordEncoder())
         .passwordAttribute("passcode");
 }

In this example, you specify that the "passcode" attribute is what should be compared with the given password. Moreover, you also specify a password encoder. It’s nice that the actual password is kept secret on the server when doing server-side password comparison. But the attempted password is still passed across the wire to the LDAP server
and could be intercepted by a hacker. To prevent that, you can specify an encryption strategy by calling the passwordEncoder() method.
In the example, passwords are encrypted using MD5 . This assumes that the passwords are also encrypted using MD5 in the LDAP server.