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伪随机数python.random

例题：NSSCTF fakerandom

import random
flag = 'xxxxxxxxxxxxxxxxxxxx'
random.seed(1)
l = []
for i in range(4):
    l.append(random.getrandbits(8))
result=[]
for i in range(len(l)):
    random.seed(l[i])
    for n in range(5):
        result.append(ord(flag[i*5+n])^random.getrandbits(8))
print(result)
# result = [201, 8, 198, 68, 131, 152, 186, 136, 13, 130, 190, 112, 251, 93, 212, 1, 31, 214, 116, 244]

首先运行看看l里面有什么

import random
flag = 'xxxxxxxxxxxxxxxxxxxx'
result = [201, 8, 198, 68, 131, 152, 186, 136, 13, 130, 190, 112, 251, 93, 212, 1, 31, 214, 116, 244]
key = []
random.seed(1)
l = []
for i in range(4):
    l.append(random.getrandbits(8))
#print(l)
result=[]
for i in range(len(l)):
    random.seed(l[i])
    for n in range(5):
        key.append(random.getrandbits(8))
print(key)
# result = [201, 8, 198, 68, 131, 152, 186, 136, 13, 130, 190, 112, 251, 93, 212, 1, 31, 214, 116, 244]

再把key提取出来，再异或

import random
flag = 'xxxxxxxxxxxxxxxxxxxx'
result = [201, 8, 198, 68, 131, 152, 186, 136, 13, 130, 190, 112, 251, 93, 212, 1, 31, 214, 116, 244]
key = [135, 91, 149, 7, 215, 222, 193, 206, 108, 233, 219, 53, 164, 47, 181, 111, 123, 185, 25, 137]
random.seed(1)
l = []
for i in range(4):
    l.append(random.getrandbits(8))
#print(l)
for i in range(len(l)):
    random.seed(l[i])
    for n in range(5):
        key.append(random.getrandbits(8))
for i in range(len(result)):
    print(chr(result[i] ^ key[i]),end='')
# result = [201, 8, 198, 68, 131, 152, 186, 136, 13, 130, 190, 112, 251, 93, 212, 1, 31, 214, 116, 244]

NSSCTF{FakeE_random}，得到flag

更新: 2024-07-02 13:31:23
原文: https://www.yuque.com/chaye-apqbl/vsc85q/tihnf3qxk2bphuwh