GipsyT
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找到登录页面http://1.14.97.218:28261/home/login/
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登录得到flag
吃豆人吃豆魂
在index.js中找到flagbase加密之后的
Crypto
easystream3
经过4次getrandbits(8)之后state重置了之后是三个getrandbits已知
可以爆破出mask(非预期)有点慢
s=[189, 81, 22, 153, 205, 197, 241, 3, 18, 128, 36, 253, 5, 200, 170, 131, 25, 71, 9, 196, 164, 161, 9, 0, 7, 123, 149, 121, 32, 122, 149, 131, 170, 252, 189, 68, 162, 164, 153, 67]
b='DASCTF{'
a=[]
for i in range(len(b)):
a.append(ord(b[i])^s[i])
print(a)
c=0b11111001000100000100010111011010
# d=100110011000001110001010
class lfsr():
def __init__(self, seed, mask, length):
self.length_mask = 2 ** length - 1
self.mask = mask & self.length_mask
self.state = seed & self.length_mask
#print(self.state, self.mask)
def next(self):
next_state = (self.state << 1) & self.length_mask
i = self.state & self.mask & self.length_mask
output = 0
while i != 0:
output ^= (i & 1)
i = i >> 1
next_state ^= output
self.state = next_state
return output
def getrandbit(self, nbit):
output = 0
for _ in range(nbit):
output = (output << 1) ^ self.next()
return output
for i in range(2**31,2**32):
b = lfsr(c, i, 32)
if(b.getrandbit(8)==153):
if(b.getrandbit(8)==131):
if(b.getrandbit(8)==138):
print(i)
seed=2226048585
f=lfsr(c,seed,32)
for i in s:
print(chr(f.getrandbit(8)^i),end='')
#TF{88ac22ea2ce99c7a325fe6ce2ddd3718}
easyrsrsa1
hint:共模攻击
两次encode之后得到两个矩阵即可解得原矩阵
比赛时矩阵逆元没想到直接求逆。。
from gmpy2 import *
e1 = next_prime(65537)
e2 = next_prime(e1)
key1=
key2=
n=
def egcd(a, b):
if a == 0:
return (b, 0, 1)
else:
g, y, x = egcd(b % a, a)
return (g, x - (b // a) * y, y)
c1 = matrix(Zmod(n),key1)
c2 = matrix(Zmod(n),key2)
s = egcd(e1, e2)
s1 = s[1]
s2 = s[2]
if s1 < 0:
s1 = - s1
c1 = c1.inverse()
elif s2 < 0:
s2 = - s2
c2 = c1.inverse()
m = power_mod(c1,s1,n)*power_mod(c2,s2,n)
flag = []
for i in range(5):
for j in range(5):
if int(m[i][j])>1000:
print(int(m[i][j])-n,end=' ')
else:print(m[i][j],end=' ')
MISC
好怪哦
010打开发现他是倒的PK
逆一下
with open("fuck.zip","rb") as f:
a=f.read()
with open("1.zip","wb") as f1:
f1.write(a)
解压得到flag.png
发现他缺少头加上png头得到文件
改高度得到flag