550

550C

这是550C，目前最强大的自感知、自适应、自组织可重塑编译计算核心。

#sage
from hashlib import sha256
from os import urandom
from functools import reduce


class ECLCG:
    def __init__(self,seed_x:int):
        p = 115792089237316195423570985008687907853269984665640564039457584007908834671663
        a = 0
        b = 7
        E=EllipticCurve(Zmod(p),[a,b])

        G = E.gens()[0]
        self.increment = E.random_point()
        self.status = G * seed_x
        
    def extract(self):
        ret = self.status
        self.status += self.increment * 550
        return ret
    
    def getrandbits(self,n:int):
        ls = []
        
        for i in range(ceil(n/256)): 
            x,y = self.extract().xy()

            h1 = bin(x >> 144)[2:]
            f1 = int(h1[:len(h1)//2] + bin(int.from_bytes(urandom(1),'big'))[2:] + h1[len(h1)//2:] + bin(int.from_bytes(urandom(1),'little'))[2:],2)

            h2 = bin(y >> 144)[2:]
            f2 = int(h2[:len(h2)//2] + bin(int.from_bytes(urandom(1),'big'))[2:] + h1[len(h1)//2:] + bin(int.from_bytes(urandom(1),'little'))[2:],2)

            ls.append(f1 << 128 | f2)
            
        ls[-1] >>= (-n) % 256
        return reduce(lambda x,y: x*2^256+y, [ls[-1]] + ls[:-1])
    
if __name__=='__main__':
    e = ECLCG(int.from_bytes(urandom(32),'big'))
    flag = b'nctf{}'
    
    print("1 for fetching a random number, 2 for getting encrypted flag, 3 for exit")
    
    for _ in range(550):
        opt=int(input())
        if opt==1:
            print(e.getrandbits(550))
        
        elif opt==2:
            pass
        
        elif opt==3:
            print("Bye~")
            break
        
        else:
            print("Invalid input")
            

Arcahv

"Delightful."

Sign

这是恢复互联网的密钥，密码是实时生成的三万个随机数。

燕归

这时候就适合来一局活动身体的叶灵纵啊！

寒凝