# Homecooked

This is kinda more rev imo but whatever.

We don't need to understand the main body of the script that much.

What we need to know is that it gets to incredibly large numbers, at which point the two functions it uses - a and b - become much too slow and inefficient to be useful.

Let's review the two functions: What do they do?

Function a simply iterates through all numbers between 2 and num - 1, and returns False if num % i == 0. Essentially, it checks if any numbers below a number are divisible by a number. What's that?

A prime checker.

We can just use `Crypto.Util.number.isPrime`, which is much more efficient.

As for b, it's much simpler. It just checks if the reverse of the string version of the number is the same as the number - checks if it's a palindrome. I just copied some more efficient code off stack overflow.

```python
def a(num):
    from Crypto.Util.number import isPrime
    return isPrime(num)  

def b(num):
    n = num
    rev = 0
    while num > 0:
        dig = num % 10
        rev = rev * 10 + dig
        num = num // 10
    if n == rev:
        return True
    return False
```

## Flag: flag{pR1m3s\_4re\_co0ler\_Wh3n\_pal1nDr0miC}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://the-winrars.gitbook.io/writeups/2020-writeups/nahamconctf/crypto/homecooked.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.