buuctf 派大星的烦恼

题目如下

首先找到伤疤并提取出来，发现一共有256个数据，根据题目中的提示答案为32位的字符串，再根据伤疤只有两种状态22和44，联想到每8个伤疤拼成8位二进制，22表示0,44表示1，组成一个二进制串

0110110000101100000011000110110010011100101011000000110010000110101011000010110010001100000111000010110001000110001001101010110001100110101001100110110001000110011011001010011010101100010001100010110011000110101001100010110011001100000111001100110001001100

将这个二进制串每8位组成一个二进制数，并转为hex，将hex转为字符串输出，即可得到答案。

with open("E:\Download\misc\派大星的烦恼.bmp","rb") as fr:
    res = fr.read()[4000:4256]
    tmp = []
    for v in res:
        if v == 34:
            tmp.append(0)
        else:
            tmp.append(1)
    fr.close()
for i in range(len(tmp)):
    tmp[i] = str(tmp[i])
a = "".join(tmp)
print(a)
b = []
for i in range(0,len(a),8):
    b.append(int(a[i:i+8],2))
w = ""
for v in b:
    w+=str(hex(v))[2:]
print(w)

 

6c2cc6c9cacc86ac2c8c1c2c4626ac66a66c466ca6ac462cc6a62ccc1ccc4c，发现这个hex串并不正确，无法解码，那么就将原本的二进制串逆序一下试试，

with open("E:\Download\misc\派大星的烦恼.bmp","rb") as fr:
    res = fr.read()[4000:4256]
    tmp = []
    for v in res:
        if v == 34:
            tmp.append(0)
        else:
            tmp.append(1)
    fr.close()
for i in range(len(tmp)):
    tmp[i] = str(tmp[i])
a = "".join(tmp)
a = a[::-1]
print(a)
b = []
for i in range(0,len(a),8):
    b.append(int(a[i:i+8],2))
w = ""
for v in b:
    w+=str(hex(v))[2:]
print(w)

 

3233383334656334623565366236656635646234383134356130353936303436，

这个hex的结果23834ec4b5e6b6ef5db48145a0596046提交不正确

那么可能是对每个二进制数据逆序，而不是整体逆序

with open("E:\Download\misc\派大星的烦恼.bmp","rb") as fr:
    res = fr.read()[4000:4256]
    tmp = []
    for v in res:
        if v == 34:
            tmp.append(0)
        else:
            tmp.append(1)
    fr.close()
for i in range(len(tmp)):
    tmp[i] = str(tmp[i])
a = "".join(tmp)
print(a)
b = []
for i in range(0,len(a),8):
    t = a[i:i+8]
    t = t[::-1]
    b.append(int(t,2))
w = ""
for v in b:
    w+=str(hex(v))[2:]
print(w)

3634303639353061353431383462643566653662366535623463653433383332，

这个hex的结果6406950a54184bd5fe6b6e5b4ce43832，提交成功