[FSCTF 2023]Tea_apk HubuKMenZe的WriteUp

JADX打开，是xxtea加密
py脚本:

import base64
import xxtea

c=base64.b64decode('vlgg9nNjUcYuWzBSSOwKxbMD2rhFgf4zuiyMpLxpNkM=')
print(c)
key=b'ABvWW7hqwNvHUhfP'
print(xxtea.decrypt(c,key))

也可以使用密码学工具

c语言解密：

#include <stdio.h>
#include <stdint.h>

#define MX (((z>>5^y<<2) + (y>>3^z<<4)) ^ ((sum^y) + (key[(p&3)^e] ^ z)))
unsigned int key[4]={1467368001, 1902655319, 1215712887, 1348888661};

int main()
{
	
	unsigned int v[8]={4129315006, 3327222643, 1378900782, 3305827400, 3101295539, 872317253, 2760649914, 1127639484};
	int len=8;
	int rounds=52/len+6;
	unsigned int delta=0x9E3779B9;
	unsigned int sum=rounds*delta;
	unsigned int y=v[0];
	unsigned int e,p,z;
	do
        {
            e = (sum >> 2) & 3;
            for (p=len-1; p>0; p--)
            {
                z = v[p-1];
                y = v[p] -= MX;
            }
            z = v[len-1];
            y = v[0] -= MX;
            sum -= delta;
        }
        while (--rounds);
    
    for(int i=0;i<len;i++)
    	printf("%x ",v[i]) ;
	return 0;
 }