BUUCTF_N1book_[第七章 CTF之CRYPTO章]BabyRSA

题目：

from Crypto.Util.number import *

flag = bytes_to_long("n1book{*********}")

p = getPrime(128)
q = getPrime(128)
n = p * q
e = 65537

cipher = pow(flag, e, n)
print n, cipher

# 69343391982073836527260787066436662760820725339907775857387709078502658633087 
# 19914364722342610626569065936888842248099105322649309104924491672406432347316

已知n，用yafu分解n，得到q，p：

q=306646691207889915109374013611076713401

p=226134486267985710544345427491176087287

 

那么已知p，q，n，e，就可以脚本解m（flag）

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import binascii
import gmpy2
import Crypto.Util
p=226134486267985710544345427491176087287
q=306646691207889915109374013611076713401
e=65537
c=19914364722342610626569065936888842248099105322649309104924491672406432347316
n=q*p

phi=(p-1)*(q-1)
d=gmpy2.invert(e,phi)
m=pow(c,d,n)
print(hex(m))
print(binascii.unhexlify(hex(m)[2:].strip("L")))

flag：

flag{ju5t_f4ctor1z3_N}