Ant cannot find package javax/crypto

Hello,
I've added some encryption tools to my project and
IDEA's ant complains:
Sematic error: You need to modify classpath,...
Package javax/crypto could not be found in ]]>

javax/crypto is part of jdk 1.4 , right?

the offending line is:

import javax.crypto.*;

as a note my native ant version 1.5.4
has no problem compiling the project.