一道逆向出题笔记

　　因为我菜，没人找过我出题。突然有个师傅找我出题我还一阵受宠若惊！

　　我说pwn题放一放，因为我也是菜鸡。。。我可以试着出一道逆向。然后逆向题目就诞生了！

 1 def verification():
 2     part1 = 'flag{'
 3     part2 = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxx'
 4     part3 = '}'
 5     tmp = ''
 6     part2_1 = part2[:7]
 7     part2_2 = part2[7:20]
 8     part2_3 = part2[20:]
 9     for i in range(len(part2_1)):
10         tmp += chr(ord(part2_1[i])+1)
11 
12     for i in range(len(part2_2)):
13         tmp += chr(ord(part2_2[i])+0)
14 
15     for i in range(len(part2_3)):
16         tmp += chr(ord(part2_3[i])-1)
17 
18     ciphertext = '''M2gf`2t_short_y0u_nedc^Oxsg/m'''
19     true_flag = part1 + part2 + part3
20 
21 def story():
22     print('One day, after the rain, you were in front of the window and looked at the beautiful scenery outside. You have a girlfriend in your heart. Does she have an umbrella? Will she be cold? Did she eat? Will she be in a bad mood? how old is she? What is her name? Oh, thinking of tears falling out of contention. At this time, you received a letter from your distant buddy.')
23     print(r'"I finally became the person I hated the most!"')
24     print(r'You comfort: "Hahaha, everyone is like this, do not be sad. Who do you hate most when you were young?"')
25     print(r'"Rich people"')
26     print(r'At this time, your heart is more sad, but there is always a voice echoing in your mind "pyinstaller! Pyinstaller! Pyinstaller!"')
27     print('py is your girlfriend!')
28 
29 def check():
30     ysr = input()
31     if(ysr[:5]=='flag{' and ysr[-1:]=='}'):
32         print('Good!!!')
33         print('But!!!Not necessarily right!')
34     else:
35         print('Flag_is_wrong!')
36 if __name__ == '__main__':
37     story()
38     print("Please enter flag:")
39     check()
40     input()