##`Night Coder`题解

题目地址：**https://ctf.bugku.com/challenges/detail/id/441.html**

题目大意：

-给了随机排列后的flag

-random种子是时间，提示当时是在2022年某个周四凌晨

```

import random

import datetime

from secret import flag

#Im a night coder, i coded this at night (thursday morning)

def seed_shuffler(my_list, seed):

  random.seed(seed)

  random.shuffle(my_list)

  return my_list

seed=int(datetime.datetime.now().strftime('%Y%m%d%H%M'))

flag = [f for f in flag]

enc = seed_shuffler(flag,seed)

print("".join(enc))

#result at that time: "N_gs{aesD_he_3AtrsOLlh3ROT1sECRl0m}s"

```

做题思路：

-遍历2022年所有周四的凌晨0:00-6:00，求解flag

### 解题脚本：

```python

fromdatetimeimportdatetime, timedelta

importrandom

defseed_shuffler(my_list,seed):

    random.seed(seed)

    random.shuffle(my_list)

   returnmy_list

definverse_seed_shuffler(shuffled,seed):

    n=len(shuffled)

   id=list(range(n))

   id=seed_shuffler(id, seed)

    m={id[i]: iforiinrange(n)}

   return[shuffled[m[i]]foriinrange(n)]

c="N_gs{aesD_he_3AtrsOLlh3ROT1sECRl0m}s"

c=[chforchinc]

start=datetime(2022,1,1)

cur=start+timedelta(days=(3-start.weekday()+7)%7)

whilecur.year==2022:

   forhourinrange(0,6):

       forminuteinrange(0,60):

            t=cur.replace(hour=hour,minute=minute).strftime('%Y%m%d%H%M')

            f=inverse_seed_shuffler(c,int(t))

            f="".join(f)

           if"shellmates"inf:

               print(cur)

               print(f)

    cur+=timedelta(weeks=1)

# 2022-05-26 00:00:00

# shellmates{N1ghT_C0D3Rs_ArE_LOOs3Rs}

```