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Welcome to NYCTF's reverse engineering tutorial

This tutorial will teach you the reverse engineering basics needed to ace NYCTF :)

Google drive folder with everything: link

There are 3 short tutorial videos, followed by a few practices to help you polish your skills.

Tutorials

Do follow along with these videos!

• Part 1 (1min 28s): Setting up

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Hints

Segment tree

Hint #1

This questions wants you to implement a conventional segment tree. You can use the nyrcs template

Hint #2

It wants you to find the minimum instead of the sum. How do you do that?

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Steps taken to get cms up and running

Cms was installed onto a raspberry pi running 64x raspbian through docker. This document details the process. It assumes you are working from the terminal.

Before everything

sudo apt-get update && sudo apt-get upgrade to have up-to-date apt info

Get CMS source

Note that we install through the docker route to avoid the suffering that comes with manually resolving dependencies.

1. Install git thru apt with sudo apt-get install git.

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Dijkstra

#include <iostream>
#include <queue>
#include <vector>
#include <limits.h>

using namespace std;

typedef long long int ll;

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Hints

Subgraphs

Hint #1

Use DFS for this. Approach is the same as with BFS (refer to session 7 slides), except that you use DFS.

Dijkstra

Hint #0

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2 Solutions for Subgraphs

Smart loop

Uses the vector visited.

Special optimization:

1. With the vector visited,
2. for (int i = 0; i<nodes; i++){
3. if (!visited[i]){do bfs and increment the counter by 1}

This avoids iterating through the whole visited vector every time. It only does so once.

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Hints & solutions

Wormholes

Hint 1

When defining a DP function, think about all the possible ways to get to where you are from ONE step before.

Also assume that if your cases are correct, all your dp results are correct.

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Noi notes

Boilerplate

Template

#include <iostream>
#define num long int

using namespace std;

int main(){

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