190403-lab1

sysmagic.c

 

void get_flag(){
        int fd ;
        int password;
        int magic ;
        char key[] = "Do_you_know_why_my_teammate_Orange_is_so_angry???";
        char cipher[] = {7, 59, 25, 2, 11, 16, 61, 30, 9, 8, 18, 45, 40, 89, 10, 0, 30, 22, 0, 4, 85, 22, 8, 31, 7, 1, 9, 0,
126, 28, 62, 10, 30, 11, 107, 4, 66, 60, 44, 91, 49, 85, 2, 30, 33, 16, 76, 30, 66};
        fd = open("/dev/urandom",0);
        read(fd,&password,4);
        printf("Give me maigc :");
        scanf("%d",&magic);
        if(password == magic){
                for(int i = 0 ; i < sizeof(cipher) ; i++){
                        printf("%c",cipher[i]^key[i]);
                }
        }
}
 
 
int main(){
        setvbuf(stdout,0,2,0);
        get_flag();
        return 0 ;
}  

 

slv.py

def main():
 
        flag=""
 
        key="Do_you_know_why_my_teammate_Orange_is_so_angry???"
 
        cipher = [7, 59, 25, 2, 11, 16, 61, 30, 9, 8, 18, 45, 40, 89, 10, 0, 30, 22, 0, 4, 85, 22, 8, 31, 7, 1, 9, 0, 126, 28
, 62, 10, 30, 11, 107, 4, 66, 60, 44, 91, 49, 85, 2, 30, 33, 16, 76, 30, 66]
 
        for i in range(0, len(cipher)):
 
                flag += chr(ord(key[i]) ^ cipher[i])
 
        print (flag)
 
 
 
if __name__ == '__main__':
 
        main()

이렇게 python으로 짜서 flag값을 구해도 되고

디버깅으로 조건문을 맞춰줘도 flag값이 나온다.