This module is in alpha-testing. Build in the usual way; send bug reports
and patches to me at the address below. From the documentation:

NAME
   Term::ReadPassword - Asking the user for a password

SYNOPSIS
     use Term::ReadPassword;
     while (1) {
       my $password = read_password('password: ');
       redo unless defined $password;
       if ($password eq 'flubber') {
         print "Access granted.\n";
         last;
       } else {
         print "Access denied.\n";
         redo;
       }
     }

DESCRIPTION
   This module lets you ask the user for a password in the
   traditional way, from the keyboard, without echoing.

   This is not intended for use over the web; user authentication
   over the web is another matter entirely. Also, this module
   should generally be used in conjunction with Perl's crypt()
   function, sold separately.

   The read_password function prompts for input, reads a line of
   text from the keyboard, then returns that line to the caller.
   The line of text doesn't include the newline character, so
   there's no need to use chomp.

   While the user is entering the text, a few special characters
   are processed. The character delete (or the character backspace)
   will back up one character, removing the last character in the
   input buffer (if any). The character CR (or the character LF)
   will signal the end of input, causing the accumulated input
   buffer to be returned. And, optionally, the character Control-C
   may be used to terminate the input operation. (See details
   below.) All other characters, even ones which would normally
   have special purposes, will be added to the input buffer.

   It is not recommended, though, that you use the as-yet-
   unspecified control characters in your passwords, as those
   characters may become meaningful in a future version of this
   module. Applications which allow the user to set their own
   passwords may wish to enforce this rule, perhaps with code
   something like this:

       {
         # Naked block for scoping and redo
         my $new_pw = read_password("Enter your new password: ");
         if ($new_pw =~ /([^\x20-\x7E])/) {
           my $bad = unpack "H*", $1;
           print "Your password may not contain the ";
           print "character with hex code $bad.\n";
           redo;
         } elsif (length($new_pw) < 5) {
           print "Your password must be longer than that!\n";
           redo;
         } elsif ($new_pw ne read_password("Enter it again: ")) {
           print "Passwords don't match.\n";
           redo;
         } else {
           &change_password($new_pw);
           print "Your password is now changed.\n";
         }
       }

   The second parameter to read_password is the optional
   `idle_timeout' value. If it is a non-zero number and there is no
   keyboard input for that many seconds, the input operation will
   terminate. Notice that this is not an overall time limit, as the
   timer is restarted with each new character.

   The third parameter will optionally allow the input operation to
   be terminated by the user with Control-C. If this is not
   supplied, or is false, a typed Control-C will be entered into
   the input buffer just as any other character. In that case,
   there is no way from the keyboard to terminate the program while
   it is waiting for input. (That is to say, the normal ability to
   generate signals from the keyboard is suspended during the call
   to read_password.)

   If the input operation terminates early (either because the
   idle_timeout was exceeded, or because a Control-C was enabled
   and typed), the return value will be `undef'. In either case,
   there is no way provided to discover what (if anything) was
   typed before the early termination, or why the input operation
   was terminated.

   So as to discourage users from typing their passwords anywhere
   except at the prompt, any input which has been "typed ahead"
   before the prompt appears will be discarded. And whether the
   input operation terminates normally or not, a newline character
   will be printed, so that the cursor will not remain on the line
   after the prompt.

SECURITY
   You would think that a module dealing with passwords would be
   full of security features. You'd think that, but you'd be wrong.
   For example, perl provides no way to erase a piece of data from
   memory. (It's easy to erase it so that it can't be accessed from
   perl, but that's not the same thing as expunging it from the
   actual memory.) If you've entered a password, even if the
   variable that contained that password has been erased, it may be
   possible for someone to find that password, in plaintext, in a
   core dump. And that's just one potential security hole.

   In short, if serious security is an issue, don't use this
   module.

AUTHOR
   Tom Phoenix <[email protected]>

SEE ALSO
   Term::ReadLine, the "crypt" entry in the perlfunc manpage, and
   your system's manpages for the low-level I/O operations used
   here.

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