2021寒假MISC打卡DAY14

1. [INSHack2017]hiding-in-plain-sight
   foremost
   flag{l337_h4xx0r5_c0mmun1c473_w17h_PNGs}

2. [网鼎杯 2020 青龙组]虚幻2

得到的 flag 请包上 flag{} 提交。

不明全部，稍做记录。

得到一张类似二维码的小图

将其分离出rgb三个通道（笔者用的stegsolve）

根据拼接，得到类似汉信码

存在一定的爆破和容差

from PIL import Image
from random import randint

for k in range(5):
	# 用到的三张图片就是上面说的 RGB 通道分开的图片（未放大10倍）
    R = Image.open('solved_r.bmp')
    G = Image.open('solved_g.bmp')
    B = Image.open('solved_b.bmp')
    GBR = Image.new('RGB', (31, 31))
    TMP = Image.new('RGB', (7, 7))
    GBRReadble = Image.new('RGB', (372, 372))

    n_r = 0
    n_g = 0
    n_b = 0
    p_r = R.load()
    p_g = G.load()
    p_b = B.load()
    pim = GBR.load()
    pimr = GBRReadble.load()
    tmp = TMP.load()

    for i in range(31):
        if i%3 == 0:
            for j in range(31):
                pim[i, j] = p_g[j, n_g]
            n_g = n_g + 1
        elif i%3 == 1:
            for j in range(31):
                pim[i, j] = p_b[j, n_b]
            n_b = n_b + 1
        elif i%3 == 2:
            for j in range(31):
                pim[i, j] = p_r[j, n_r]
            n_r = n_r + 1

    for i in range(0, 7):
        for j in range(0, 7):
            tmp[i, j] = pim[i, j]
            
    TMP = TMP.rotate(180)
    tmp = TMP.load() 

    for i in range(0, 7):
        for j in range(0, 7):
            pim[i, j] = tmp[i, j]       
           
    for i in range(14, 23):
        for j in range(24, 31):
            if (randint(0, 1) == 0):
                pim[i, j] = (0,0,0)