The import javax.crypto cannot be resolved

Hi, I’m trying to compile spark directly from source, and I get this error in a file called Encryptor.java. Does anyone know what’s going on here? Why can’t it find javax.crypto? By all accounts that should be included in the JRE/JDK right?

Also, is there a general page documenting building Spark from source? I’m not really a java developer, so some of the stuff with eclipse is a little opaque to me.