Using bytebuddy reflection to bypass file string check

There's this problem in Codewars
https://www.codewars.com/kata/58a3fa665973c2a6e80000c4/train/java

We will have to just square root a very big number. Of course all of us would think about BigInteger.sqrt - but the challenge itself reject these words: reflection, biginteger, bigdecimal, runtime, process, script. (P/s you can't use unicode either).

Update: also blocked "newInstance", "invoke"

Well there's no fun in doing what intended for the task, so I currently trying to bypass this by using bytebuddy (luckily they don't reject this).

import net.bytebuddy.ByteBuddy;
import net.bytebuddy.agent.ByteBuddyAgent;
import net.bytebuddy.dynamic.DynamicType.Loaded;
import net.bytebuddy.dynamic.loading.ClassReloadingStrategy;
import net.bytebuddy.implementation.FixedValue;
import net.bytebuddy.matcher.ElementMatchers;

public class Kata {	
  public static String integerSquareRoot(String n) {
    ByteBuddyAgent.install();
		Loaded<Kata> dynamicType = new ByteBuddy().redefine(Kata.class).method(ElementMatchers.named("text"))
				.intercept(FixedValue.value(new java.math.BigInteger(n).sqrt().toString())).make()
				.load(Thread.currentThread().getContextClassLoader(), ClassReloadingStrategy.fromInstalledAgent());
    return Kata.text("forsenCD");
	}
  
  public static String text(String n){
    return n;
  }
}

What it does here is to force the text() method to return what's in the intercept

This solution itself solve the task, but as you can see, it still have "BigInteger" in the intercept.

I'm noob at bytebuddy, so anyone have a way to solve this using bytebuddy reflection, that maybe can change the BigInteger in the intercept with a string (so I can use character array) to solve this.

Or maybe even using Nashorn engine to get to some JavaScript API.

Please feel free to share your thought.

Sure, since we're hacking anyway, this should be fun:

1. Instead of calling the BigInteger constructor directly, call it using reflection: Class.forName("java.math.BigInteger").newInstance(n) *
2. Now take that String literal, and apply an encoding of your choice. Base64 should do. Save the encoded string as a constant.
3. At runtime, decode the String and pass it to Class.forName.

* Does newInstance have a varargs option? If not, use getConstructors instead and call the right one.