NSSCTF_RE_[SWPUCTF 2021 新生赛]fakebase(鸽)

题目:

flag = 'xxxxxxxxxxxxxxxxxxx'

s_box = 'qwertyuiopasdfghjkzxcvb123456#$'
tmp = ''
for i in flag:
    tmp += str(bin(ord(i)))[2:].zfill(8)
b1 = int(tmp,2)
s = ''
while b1//31 != 0:
    s += s_box[b1%31]#从box里取加到s
    b1 = b1//31#取整数

print(s)

# s = u#k4ggia61egegzjuqz12jhfspfkay

最开始以为是自定义base,但是仔细看了之后其实就是从box里取字符,