C++ Buffer Overflow, strcpy, fgets, sprintf showing runtime error

Question

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int check_authentication(char* password) {
    int auth_flag = 0;
    char* password_buffer;
    char* dept;
    password_buffer = (char*)malloc(16);
    dept = (char*)malloc(10);
    printf("Your department?");
    fgets(dept, 10, stdin); //line 11
    strcpy_s(password_buffer, 16, password); //line 12
    if (strcmp(password_buffer, "AsiaPacificInst") == 0) {
        if (strcmp(dept, "NSF") == 0) {
            auth_flag = 1;
        }
    }
    if (strcmp(password_buffer, "AsiaPacificUni") == 0) {
        if (strcmp(dept, "TM") == 0) {
            auth_flag = 1;
        }
    }
    return auth_flag;
}
int main(int argc, char* argv[]) {
    char errmsg[512];
    char outbuf[512];
    char user[20];


    printf("Username: ");
    fgets(user, 20, stdin); //line 32
    if (strcmp(user, "Adm1n") == 0) {
        printf("Authorised User\n"); sprintf_s(errmsg, "Authorised User %400s", user); sprintf_s(outbuf, errmsg);  //line 34

        if (argc < 2)
        {
            printf("Usage: %s <password>\n", argv[0]); exit(0);
        }

        if (check_authentication(argv[1]))
        {
            printf("\n-=-=-=-=-=-=-=-=-=-=-=-=-=-\n");
            printf(" Access Granted.\n");
            printf("-=-=-=-=-=-=-=-=-=-=-=-=-=-\n");
        }

        else {
            printf("\n-=-=-=-=-=-=-=-=-=-=-=-=-=-\n");
            printf("\nAccess Denied.\n");
            printf("\n-=-=-=-=-=-=-=-=-=-=-=-=-=-\n");
        }


    }
    else { printf("Unauthorised User!!\n"); exit(0); }

}

I need help on to check whether the set of codes below has been written in the correct way as I'm not familiar with C++.

1. fgets (line 11 and 32)
2. strcpy_s (line 12)
3. sprintf_s (line 34)

Because these line of codes had errors earlier when I got them from another source. However, I fixed those error yet on runtime the program did not work properly. The program actually should request for a username and password and verify whether the user is authorized using the username and verify the user's department using their password. However, I could only enter the username when I run the program. It did not request me a password. Also in overall is there any other issue that may cause the program to not run properly.

Program Result when executed

Answer 1

The program doesn't request password, because it expects it to be passed as an argument like this: 'c:\yourapp.exe yourpass'. If you want it to request a password, you should modify it a bit.

Add following lines before if (check_authentication(argv[1])) line in your main function.

char password[16];
printf("Password: ");
fgets(password, 16, stdin);

Replace line if (check_authentication(argv[1])) with if (check_authentication(password))

And delete or comment out following lines:

if (argc < 2)
{
    printf("Usage: %s <password>\n", argv[0]); exit(0);
}

And finally please do not forget removing newlines after each fgets call. Removing trailing newline character from fgets() input