# A Mossad agent in Iran

Today I received the following riddle:

Topic: Math, Research, OSINT, Decoding, Code Writing.

Difficulty level: Medium — Difficult

Comments: Recommended page and pen, a place to write code (Python is better) to prove what is needed using pictures + a link to the source, in order to be convenient for everyone I was worried that Hebrew content would be available for research.

So today you are going to be Mossad agents🕵♂️ who are going to help destroy the Iranian reactor, but we have some things to explore, solve, and write.

At our disposal: a computer with a web, a page and a pen, code writing software, our brain🧠, and a headset🤔.

Why a headset? Because we are in contact with one of the agents who is in Iran and passing on information to us🤫

We must decipher and investigate and bring credible information to our spy so that we can destroy the Iranian reactor.

Our spy gave us the following information:

90% U-235

We must first research to understand what these numbers are and we will have to prove that the uranium they enrich is really meant for weapon use, when we prove that they do really enrich uranium for weapon use we can move on to the next information he passed on to us.

Our spy also passed us the following information with an explanation of it:

X, X, 2, 3, Y, 8, 13, 21, Z … STOP

He tells us about this line that it is actually A speed series goes up, ends and starts again — which causes the centrifuges (material separation devices) to remain in a constant loop that maintains a normal speed and gave us a bonus saying that if the speed gets out of control and passes the last number in the ending series they will be destroyed. We must decipher this series and the missing and write a code that will make the centrifuges out of control and destroy them, we will pass the code to our spy who will implant our malicious code in their system and we will succeed in destroying the Iranian reactor.

But there is a catch — their system knows to detect malicious code so we must use the numbers in this series in our code so that the centrifuges continue to operate until destruction and the code is not blocked.

And here is my solution attached right here, it turned out that I was the first to solve the riddle.

1. 90% U-235

The number U-235 is an isotope of uranium as can be seen in its entry in Wikipedia and is the isotope used in the nuclear industry because it is a fissile material.

This isotope is almost uncommon and therefore uranium is enriched with this isotope artificially and to use it for weapons it needs to be at least enriched to 85% of U-235, as can be seen here. But 90% is a level used to make the reactor smaller, as can be seen here.

So basically, the information we got is that uranium is enriched enough for nuclear weapons.

2. X, X, 2, 3, Y, 8, 13, 21, Z … STOP

The second part is the code quoted in the title that you immediately see is actually a Fibonacci series.

Thus the following disappear:

X = 1

Y = 5

Z = 34

I mean this is the centrifuge loop, we have to write a code for the Fibonacci series that will reach more than 34. In the code there are 9 digits, which means we have to get more than 9 digits in the Fibonacci number, I get to the 15th digit so the Iranians have no chance. This is the code in python:

>>> def fibonacci_of(n):

… if n in {0, 1}: # Base case

… return n

… return fibonacci_of(n — 1) + fibonacci_of(n — 2) # Recursive case

…

>>> [fibonacci_of(n) for n in range(15)]

[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377]