ultrasecure.py

import socket

s = socket.socket()
s.connect(("asis-ctf.ir", 12445))

s.recv(2048)
s.send("Paillier\n")
s.recv(2048)

lo = 10 ** 307
hi = 11 ** 307

while True:
    n = (lo + hi) / 2
    s.recv(2048)
    print "Sending N={}".format(n)
    s.sendall("E\n")
    s.recv(2048)
    s.sendall("{}\n".format(n))
    result = s.recv(2048)
    print result
    if "None" in result:
        print "GOT N: ", n+1
        exit(0)
    elif "Your secret is" in result:
        print "TOO LOW!"
        lo = n
    else:
        print "TOO HIGH!"
        hi = n