193 lines
4.3 KiB
Python
Executable File
193 lines
4.3 KiB
Python
Executable File
#!/usr/bin/env python3
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import hashlib
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import qrcode
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from PIL import Image
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import numpy as np
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import requests
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def get_user():
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r = requests.get("https://brachiosaure.france-cybersecurity-challenge.fr/")
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name = r.text.split("text-warning\">")[1].split('<')[0]
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return name
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def get_digest(name):
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m = hashlib.sha512()
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m.update(name.encode())
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digest = m.digest()
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return digest
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def linearize_serial(matrix_serial):
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serial = bytearray()
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for line in matrix_serial:
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for b in line:
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serial.append(b % 256)
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return bytes(serial)
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def img_to_matrix(img):
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array = list(img.getdata())
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width, height = img.size
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matrix_img = [[array[i * width + j] for j in range(width)] for i in range(height)]
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return matrix_img
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def matrix_to_img(mat, path):
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array = np.uint8(mat)
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img = Image.fromarray(array)
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img.save(path)
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def gen_qrcode(data, path):
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qr = qrcode.QRCode(version = 1, box_size = 2, border = 2)
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qr.add_data(data)
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qr.make()
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qr_usr = qr.make_image()
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qr_usr.save(path)
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def identitymatrix(n):
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return [[int(x == y) for x in range(0, n)] for y in range(0, n)]
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def get_flag(name):
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files = {
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"upload1": open(f"{name}_usr.png", "rb"),
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"upload2": open(f"{name}_serial.png", "rb")
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}
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r = requests.post("https://brachiosaure.france-cybersecurity-challenge.fr/login", files=files)
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for line in r.text.split('\n'):
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if "FCSC{" in line:
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print(line)
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name = get_user()
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digest = get_digest(name)
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matrix_usr = [[digest[i * 8 + j] for j in range(8)] for i in range(8)]
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matrix_usr = np.array(matrix_usr)
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matrix_serial = np.dot(matrix_usr, matrix_usr)
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serial = linearize_serial(matrix_serial)
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gen_qrcode(digest, "user.png")
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gen_qrcode(serial, "serial.png")
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img_usr = Image.open("./user.png", "r")
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img_serial = Image.open("./serial.png", "r")
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matrix_img_usr = img_to_matrix(img_usr)
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matrix_img_serial = img_to_matrix(img_serial)
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def invert(usr, serial):
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# Add empty and identity matrices to make it invetible
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usr = make_invertible(usr)
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serial = make_invertible(serial)
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n = len(usr)
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# Total size after redimensionning
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new_n = n * 2
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# The magic inversion by swapping corners and computing matrix opposite
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usr_inv = invert_magic(usr)
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serial_inv = invert_magic(serial)
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# Will hold the final user png
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new_usr = []
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# Will hold the final serial png
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new_serial = []
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# Create the new_usr
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for i in range(new_n):
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line = [0] * new_n
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if i < n:
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for j in range(n):
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line[j] = usr[i][j]
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if i >= n:
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for j in range(n):
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line[j + n] = int(serial_inv[i - n][j])
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new_usr.append(line)
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# Create the new_serial
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for i in range(new_n):
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line = [0] * new_n
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if i < n:
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for j in range(n):
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line[j] = int(usr_inv[i][j])
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if i >= n:
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for j in range(n):
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line[j + n] = serial[i - n][j]
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new_serial.append(line)
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return new_usr, new_serial
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def make_invertible(mat):
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res = []
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n = len(mat)
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ident = identitymatrix(n)
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# Add the identity matrix below the original
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for line in ident:
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mat.append(line)
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for i in range(len(mat)):
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line = mat[i]
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for j in range(n):
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# Add the identity matrix at the right of the original
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if i < n:
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line.append(ident[i][j])
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# Add the empty matrix at the bottom right corner
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else:
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line.append(0)
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return mat
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def invert_magic(mat):
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n_tot = len(mat)
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n = n_tot // 2
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#Create a new empty matrix to hold the result
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res = [[0 for _ in range(n)] for _ in range(n)]
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ident = identitymatrix(n)
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# Add the identity matrix below
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for line in ident:
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res.append(line)
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for i in range(len(mat)):
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line = res[i]
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for j in range(n):
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# Identity matrix on the right
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if i < n:
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line.append(ident[i][j])
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# Oposite of the original in the bottom right corner
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else:
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el = -mat[i - n][j] % 256
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line.append(el)
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return res
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res_usr, res_serial = invert(matrix_img_usr, matrix_img_serial)
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matrix_to_img(res_usr, f"{name}_usr.png")
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matrix_to_img(res_serial, f"{name}_serial.png")
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get_flag(name)
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