simple string obfuscation

    extern "C" __declspec(dllexport) void encode(char* user) {

        string filename = Get_List_Directory() + "\\preferences.ini";
        string tmp{};
        string username = string(user);
        fstream f;
        stringstream ss;
        bool containsKey = false;
        f.open(filename, fstream::out | fstream::in | fstream::app);

        if (!f.is_open()) {
            Log("error  failed to open file preferences.ini");
            return;
        }
        while (getline(f, tmp)) {  //read file into ss
            if (tmp.find("username=") != tmp.npos) {
                containsKey = true;
            }
            ss << tmp << '\n';
        }

        srand(time(0));
        tmp = "";
        int num = 0;
        for (int i = 0; i < username.size() + 1; i++) {
            int j = 0;
            while (j < i + 1) {
                num = 0;
                while (num < 33) {
                    num = rand() % 127;
                }
                tmp += (char)num;
                j++;
            }
            if (i == username.size()) {
                break;
            }
            tmp += username[i];
        }
        f.close();
        f.open(filename, fstream::out | fstream::app);
        if (!containsKey) {
            cout << tmp;
            f << "username=" << tmp;
            return;
        }
        f.close();
        f.open(filename, fstream::out);
        containsKey = false;
        while (getline(ss, username)) {
            cout << username << '\n';
            if (username.find("username=") != username.npos) {
                containsKey = true;
            }
            else if (containsKey && username.find("=")) {
                containsKey = false;
                f << username << '\n';
            }
            else if (!containsKey) {
                f << username << "\n";
            }
        }
        f << "username=" << tmp;
        f.close();
    }
    extern "C" __declspec(dllexport) int decode(int num) {
        string filename = Get_List_Directory() + "\\preferences.ini";
        string tmp{};
        fstream f;
        bool containskey = false;
        f.open(filename, fstream::in);
        if (!f.is_open()) {
            Log(" error failed to open file");
            return 0;
        }
        while (getline(f, tmp)) {
            if (tmp.find("username=") != tmp.npos) {
                containskey = true;
                break;
            }
        }

        if (containskey) {
            tmp = tmp.substr(tmp.find("=") + 1, tmp.size() - (tmp.find("=") + 1));
            int n = 1;
            int b = 0;

            b += num;
            while (n < num + 2) {

                b += n;
                n++;
                if (b > tmp.size() - 1) {
                    return 0;
                }
            }
            return (int)tmp[b];
        }
        return 0;
    }