HelloGhidra.c

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

#define XOR_PASSWORD    "]pyyzJR}|qgt4" // Hello_Ghidra! xor 0x15
#define XOR_KEY         0x15
#define PASSWORD_LEN    13

int check_password(char *password)
{
    char buf[PASSWORD_LEN];
    int i;

    if (strlen(password) != PASSWORD_LEN)
        return -1;

    for (i = 0; i < PASSWORD_LEN; i++)
        buf[i] = password[i] ^ XOR_KEY;
    
    if (strncmp(buf, XOR_PASSWORD, PASSWORD_LEN) != 0)
        return -1;

    return 0;
}

int main(int argc, char *argv[])
{
    if (argc < 2) {
        printf("Usage: %s <password>\n", argv[0]);
        return -1;
    }

    if (check_password(argv[1]) < 0) {
        printf("Incorrect password.\n");
        return -1;
    }

    printf("Congratulations! flag{%s}\n", argv[1]);
    return 0;
}