Tags: rev reverseengineering reverse
Rating:
We have to reverse the binary. Decompiled code:
The program basically XOR our input with number 3 and then compare the result with 'flag_matrix' which is:
The XOR has the commutative property:
input ^ 3 = flag_matrix
flag_matrix ^ 3 = input
Let's write a program wich XOR the flag with 3:
```c
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <string.h>
void main(){
char v7[104] = "[.NBPx67m47\\26\\a7g\\74\\o2`0m60\\`k0`h2m5~" ;
int i;
char s1;
for (i = 0; v7[i]; ++i){
s1 = v7[i]^3;
printf("%c", s1);
}
return;
}
```
# FLAG
X-MAS{54n74_15_b4d_47_l1c3n53_ch3ck1n6}
