Spring Security e MD5

import org.springframework.security.authentication.encoding.Md5PasswordEncoder;
import org.springframework.security.authentication.encoding.PasswordEncoder;

public class EncriptarMD5 {
	public static String encriptar(String senha) {
		PasswordEncoder encoder = new Md5PasswordEncoder();
		senha = encoder.encodePassword(senha, null);
		return senha;
	}
}

public String salvar() {

		this.usuario.setUser_tema("afternoon");
		
		String senha  = EncriptarMD5.encriptar(usuario.getUser_senha());
		usuario.setUser_senha(senha);
		UsuarioRN usuarioRN = new UsuarioRN();
		usuarioRN.salvar(this.usuario);

		usuario = new Usuario();
		return "/admin/principalAdmin";
	}

<authentication-manager>
		<authentication-provider>
			<password-encoder hash="md5" />
			<jdbc-user-service data-source-ref="omissoesDataSource"
				authorities-by-username-query="SELECT u.user_login, p.permissao 
											 FROM usuario u, usuario_permissao p 
											WHERE u.user_codigo = p.usuario 
											  AND u.user_login = ?"
				users-by-username-query="SELECT user_login, user_senha, estado_ativo 
									   FROM usuario 
									  WHERE user_login = ?" />
		</authentication-provider>
	</authentication-manager>

<h:panelGroup rendered="#{!empty param.login_error}">
				<h:outputText value="Login e Senha não Confere !!!"
					style="color: red;font-size:22px;" />
				<br />
			</h:panelGroup>

			<form id="login" method="post"
				action="#{request.contextPath}/j_spring_security_check">
				<center>
					<p:panelGrid columns="2">
						<f:facet name="header">.: Digite os dados :.</f:facet>
						<h:outputLabel for="j_username" value="Login" />
						<h:inputText id="j_username" required="true" />

						<h:outputLabel for="j_password" value="Senha" />
						<h:inputSecret id="j_password" required="true" />

						<h:outputLabel />
						<h:commandButton type="submit" value="Login" />
					</p:panelGrid>
				</center>
			</form>