buuctf 梅花香之苦寒来 详解

下载得到图片
010editor发现文件尾有大量数据，为16进制数据

将16进制数据复制到 hex.txt 利用脚本转化为 ascii 获取坐标点

with open('hex.txt', 'r') as h:
    h = h.read()
with open('./ascii.txt', 'a') as a:
    for i in range(0, len(h), 2):
        tmp = '0x'+h[i]+h[i+1]
        tmp = int(tmp, base=16)
        if chr(tmp) != '(' and chr(tmp) != ')':
            a.write(chr(tmp))

用 matplotlib 绘图得到二维码

import matplotlib.pyplot as plt
import numpy as np


x, y = np.loadtxt('./ascii.txt', delimiter=',', unpack=True)
plt.plot(x, y, '.')
plt.show()

最终脚本

import matplotlib.pyplot as plt
import numpy as np


with open('hex.txt', 'r') as h:
    h = h.read()
with open('./ascii.txt', 'a') as a:
    for i in range(0, len(h), 2):
        tmp = '0x'+h[i]+h[i+1]
        tmp = int(tmp, base=16)
        if chr(tmp) != '(' and chr(tmp) != ')':
            a.write(chr(tmp))


x, y = np.loadtxt('./ascii.txt', delimiter=',', unpack=True)
plt.plot(x, y, '.')
plt.show()