There are two methods in which input can be taken in a more secure way:
- Do not display any content.
- Display a special character such as an asterisk instead of actual content.
In this method, input content will be invisible. This can be implemented in two ways:
using <windows.h>:
Program 1:
Below is the program where console mode is set to enable, echo input, and reset the console mode:
// C++ program to take the input // invisibly #include <iostream> #include <windows.h> using namespace std;
// Function take password and // reset to console mode std::string takePasswdFromUser() { HANDLE hStdInput
= GetStdHandle(STD_INPUT_HANDLE);
DWORD mode = 0;
// Create a restore point Mode
// is know 503
GetConsoleMode(hStdInput, &mode);
// Enable echo input
// set to 499
SetConsoleMode(
hStdInput,
mode & (~ENABLE_ECHO_INPUT));
// Take input
string ipt;
getline(cin, ipt);
// Otherwise next cout will print
// into the same line
cout << endl;
// Restore the mode
SetConsoleMode(hStdInput, mode);
return ipt;
} // Driver Code int main()
{ string input;
cout << "@root>>> " ;
// Function Call
input = takePasswdFromUser();
// Print the input
cout << input << endl;
} |
Output:
using <conio.h>:
For this getch() is used. This function takes a character input from user without buffer and doesn’t wait for the user to press “return” key.
Program 2:
Below is the C++ program to demonstrate the use of getch() in conio.h:
// C++ program to demonstrate the // use of getch() #include <conio.h> #include <iostream> using namespace std;
// Function using getch() std::string takePasswdFromUser() { string ipt = "" ;
char ipt_ch;
while ( true ) {
ipt_ch = getch();
// Check whether user enters
// a special non-printable
// character
if (ipt_ch < 32) {
cout << endl;
return ipt;
}
ipt.push_back(ipt_ch);
}
} // Driver Code int main()
{ string input;
cout << "@root>>> " ;
// Function call
input = takePasswdFromUser();
cout << input << endl;
} |
Output:
Drawback: The user can’t clear the response made earlier. When backspace is pressed, the input is returned.
Program 3:
Below is the C++ program to demonstrate the solution to the above drawback:
// C++ program to demonstrate the // solution of above drawback #include <conio.h> #include <iostream> using namespace std;
// Enumerator enum TT_Input {
// ASCII code of backspace is 8
BACKSPACE = 8,
RETURN = 32
}; // Function accepting password std::string takePasswdFromUser() { string ipt = "" ;
char ipt_ch;
while ( true ) {
ipt_ch = getch();
if (ipt_ch < TT_Input::RETURN
&& ipt_ch != TT_Input::BACKSPACE) {
cout << endl;
return ipt;
}
// Check whether the user
// pressed backspace
if (ipt_ch == TT_Input::BACKSPACE) {
// Check if ipt is empty or not
if (ipt.length() == 0)
continue ;
else {
// Removes last character
ipt.pop_back();
continue ;
}
}
ipt.push_back(ipt_ch);
}
} // Driver Code int main()
{ string input;
cout << "@root>>> " ;
// Function call
input = takePasswdFromUser();
cout << input << endl;
} |
Hiding the password by a special character(*):
The idea is to use the library <conio.h> here to hide password with asterisk(*). Below is the C++ program using conio.h to hide the password using *:
Program 4:
// C++ program to hide the password // using *(asterik) #include <conio.h> #include <iostream> using namespace std;
// Enumerator enum IN {
// 13 is ASCII for carriage
// return
IN_BACK = 8,
IN_RET = 13
}; // Function that accepts the password std::string takePasswdFromUser( char sp = '*' )
{ // Stores the password
string passwd = "" ;
char ch_ipt;
// Until condition is true
while ( true ) {
ch_ipt = getch();
// if the ch_ipt
if (ch_ipt == IN::IN_RET) {
cout << endl;
return passwd;
}
else if (ch_ipt == IN::IN_BACK
&& passwd.length() != 0) {
passwd.pop_back();
// Cout statement is very
// important as it will erase
// previously printed character
cout << "\b \b" ;
continue ;
}
// Without using this, program
// will crash as \b can't be
// print in beginning of line
else if (ch_ipt == IN::IN_BACK
&& passwd.length() == 0) {
continue ;
}
passwd.push_back(ch_ipt);
cout << sp;
}
} // Driver Code int main()
{ string input;
cout << "@root>>> " ;
// Function call
input = takePasswdFromUser();
cout << input << endl;
} |