Hakim Benoudjit h4k1m0u

Kotlin

Statically typed language.
Outputs bytecode that runs on the JVM (like Java).

Gradle

Build system for Android used for compilation, packaging (APK), and for dependency management.

Android KTX

Kotlin extensions for Android development.

What is it

An instrumentation tool for x86, Android..., that targets binary applications.

Usage

To debug live processes.
To execute your script inside another process.

Applications

Frida is used for dynamic reverse engineering (i.e. analyze a program while software is running).
Static reverse engineering software in contrast take binaries to dissect them.

File structure

Libraries: Userland/Libraries/{LibC, LibGUI...}
Games: Userland/Games/{Snake, Solitaire...}
Applications: Userland/Applications/{Calculator, Calendar...}

Ninja

SerenityOS is built using CMake and Ninja.

Target: output files of the build process (executables, libraries).
Use Ninja with CMake: cmake -G Ninja (generates a build.ninja file)
Build target: ninja

Electronic components

Breadboard: Rectangular plastic board with tiny holes to insert electronic components in them.
Jump wire: Electrical wire used to interconnect components.
Transistor: Used to amplify current, switch on/off the flow of current, and to construct logic gates.
Diodes: Allows the flow of current in one direction & blocks the other direction (like a valve).
Resistors: Limits the flow of current.
Capacitor: Stores and releases electricity (like a temporary battery).
LED: emits light when current flows through it.
Arduino devices:
Sensors: Used to monitor physical phenomena (e.g. temperature, humidity, motion, light...).

C++ syntax

List initialization

Advantage: Doesn't allow narrowing, i.e. the following throws an error:

int i {2.0f};

Direct and copy initialization

Advantage: Doesn't create a copy (practical for objects):

Below some notions about USB that could be useful to access USB devices programatically with [libusb]. For more details refer to [USB2.0 specification][usb2-specification].

Terminology

Host: Computer.
USB device: Peripheral connected to computer via USB.
Hub: USB device providing additionnal connections to the USB.
IRQ (Interrupt request): a hardware signal from device requesting attention from host.
Pipe: Logical abstraction for associating device's endpoint and host's software. There two types of pipes:
- Stream pipe: data no USB-defined structure.
Message pipe: data has a USB-defined structure.

OSI model

For systems interconnections in a network, and has 7 layers (from top to bottom):

Application: Closest to user, e.g. HTTP, FTP...
Presentation: Encryption/Decryption, Compression/decompression, e.g. jpeg, mpeg...
Session: e.g. sync file transfers with checkpoints (to avoid restarting from beginning on failure).
Transport: Flow and error control, e.g. TCP, UDP
Network: breaks/assembleds data into packets, routing, e.g. IP
Data link: connects devices that are physically in the same network, e.g. Ethernet, MAC
Pyhsical: bit (raw data), e.g. cables

	#include <limits.h>
	#include <string.h>
	#include <stdbool.h>
	#include <gd.h>

	#include "utils.h"

	/**
	* Print password written beforehand on image with steganography_write.c
	* - GD documentation: https://libgd.github.io/manuals/2.1.1/files/preamble-txt.html

	#include <gd.h>

	// C doesn't allow variable length arrays (even using a constant)
	#define N_CORNERS 3

	typedef struct {
	int x;
	int y;
	} Point;

	#include <stdio.h>
	#include <stdint.h>
	#include <stdlib.h>
	#include <string.h>
	#include <math.h>

	/**
	* Parse bitmap image to find RGB values at given row and column
	* Bitmap format: https://en.wikipedia.org/wiki/BMP_file_format
	* Tested input bitmap image saved in Gimp without color space information and in 24bits format