[网鼎杯 2020 青龙组]you_raise_me_up

题目代码

#!/usr/bin/env python
# -*- coding: utf-8 -*-
from Crypto.Util.number import *
import random

n = 2 ** 512
m = random.randint(2, n-1) | 1
c = pow(m, bytes_to_long(flag), n)
print ('m = ' + str(m))
print ('c = ' + str(c))

# m = 391190709124527428959489662565274039318305952172936859403855079581402770986890308469084735451207885386318986881041563704825943945069343345307381099559075
# c = 6665851394203214245856789450723658632520816791621796775909766895233000234023642878786025644953797995373211308485605397024123180085924117610802485972584499

可以利用python自带的discrete_log来解

from Crypto.Util.number import *
from primefac import *
from gmpy2 import *
from sympy import *

m = 391190709124527428959489662565274039318305952172936859403855079581402770986890308469084735451207885386318986881041563704825943945069343345307381099559075
c = 6665851394203214245856789450723658632520816791621796775909766895233000234023642878786025644953797995373211308485605397024123180085924117610802485972584499
n = 2 ** 512
print(discrete_log(n,c,m))
flag = 56006392793405651552924479293096841126763872290794186417054288110043102953612574215902230811593957757
print(long_to_bytes(flag))