Well, If you don't mind to use a module :)

use strict;
use warnings;
use Term::ReadKey;

my $hint = "I'm not going to tell you! You knew it already";

print "Username: ";
chomp(my $user = <STDIN>);
# validate $user

print "Password: ";
ReadMode 'noecho';
chomp(my $pass = <STDIN>);
ReadMode 'normal';
# validate $pass

print "\nYou said: username=$user, password=($hint)\n";
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