```
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#define MAX_FILE_SIZE 1024
static unsigned long long seed = 0;

void srandX(int arg1) {
seed = (unsigned long long)arg1 - 1;
}

int randX() {
seed = 0x5851f42d4c957f2d * seed + 1;
return (int)(seed >> 33);
}

int main() {
unsigned long start = 1715198460; //Wed May 08 2024 22:01:00
unsigned long end = 1715198519; //Wed May 08 2024 22:01:59

FILE *file = fopen("flag.enc", "rb");
if (!file) {
perror("Error opening encrypted file");
return 0;
}

char encrypted_data[MAX_FILE_SIZE];
size_t file_size = fread(encrypted_data, 1, sizeof(encrypted_data), file);
fclose(file);

if (file_size == 0) {
printf("Error: File is empty.\n");
return 0;
}

for (unsigned long i = start; i <= end; i++) {
srandX(i);
printf("Testing seed: %ld\n", i);

char decrypted_data[MAX_FILE_SIZE];
memcpy(decrypted_data, encrypted_data, file_size);

for (char j = 0; j < file_size; j++) {
//int rax_15 = randX();
//int rdx = rax_15 / 0x7f;
//int key = rax_15 - ((rdx << 7) - rdx);
int keyy = randX()%127;
decrypted_data[j] ^= keyy;
}
if (strstr((char*)decrypted_data, "PWNME{")) {
printf("Flag found with seed %ld: %s\n", i, decrypted_data);
return 0;
}
}

printf("No valid flag found.\n");
return 0;
}
```

Original writeup (https://medium.com/@hackthena/back-to-the-past-writeup-229c486e768f).