Right. Knowing the salt is half the battle in cracking the password.

In addition to the suggestions of our fellow monks, I can add two more points.

Use a random salt and store the password in such a way where it will be extremely difficult for someone to obtain. Such as a configuration file only readable by the application itself. Some example code follows:

use strict;

my $pass;

$| = 1;
print "password: ";
chomp($pass = <STDIN>);
print crypt_pass($pass), "\n";
exit;

sub crypt_pass {
        my $p = shift;
        return unless $p;

        my $salt = chr(65+rand(27)).chr(65+rand(27));
        return crypt($p, $salt);
}
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Another thing you can do is use the first two characters of the password as the salt, then strip those two characters off before you store it.

use strict;

my $pass;

$| = 1;
print "password: ";
chomp($pass = <STDIN>);
print crypt_pass($pass), "\n";
exit;

sub crypt_pass {
        my $p = shift;
        return unless $p;

        crypt($p, $p) =~ /..(.*)/;
        my $cpass = $1;
        return $cpass;
}
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