Do you need to decrypt this password again or check that a user knows this password ?

If you need to decrypt it again in the script it will only be obfuscated and anyone with enough Perl knowledge will be able to decrypt it too.

if you just need to check a user knows it you can store a hash of the password (MD5 hash should do the trick) and then compare a hash of the user attempt. To make this a little more secure you should mix the password with a salt before hashing it. This stops making a dictionary of many password hashes and then seeing if yours is already know. The salt can be stored clear along with the password hash.

#!/usr/bin/perl
use strict;
use warnings;
use Digest::MD5 qw (md5_base64);

print "enter a password to store: ";
my $password = <STDIN>;
my $salt = time;
my $digest = md5_base64($password.$salt);

print "salt: $salt hash: $digest\n";

my $enter = 0;
until ($enter) {
    print "Speak friend and enter: ";
    my $try = <STDIN>;
    my $tryhash = md5_base64($try.$salt);
    $enter++ if $tryhash eq $digest;
}
print "Welcome friend\n";
__END__
# output ...
enter a password to store: friend
salt: 1235062413 hash: 2eJWH+Yjy1Fw8J9wW6vmAg
Speak friend and enter: enemy
Speak friend and enter: friend
Welcome friend
[download]

Cheers,
R.

Do you just want to encrypt a password with the standard unix hash method in your script? Here is a small script that encrypts a password:

use strict;

my $inp;

srand(time() ^ $$);

print "Please enter password:\n";
system "stty -echo";
chop($inp= <STDIN>);
print "\n";
system "stty echo";
my $i= chr(rand(26)+ord('a')) . chr(rand(26)+ord('a'));
print crypt( $inp,$i ),"\n";
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But you can't use the encrypted form to connect to some service that needs the password. That is not possible!

If that is what you wanted you have to store the password in the clear. You can only really secure it if you store the password in a file only the script can read (in unix the script has to have its suid-flag set so it is executed with the rights of the script owner and the password file should be only readable by the script owner)

#!/usr/bin/perl
use warnings;
use strict;
#by fokat of perlmonks

my $string = 'justanotherperlhacker';
print "$string\n";

my $obscure =  pack("u",$string);
print "$obscure\n";

my $unobscure = unpack(chr(ord("a") + 19 + print ""),$obscure);

print "$unobscure\n";
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$password = "abc123";
$encrypt  = join('', map { ord($_) } split '', $password);
[download]

If you can suggest me a way in which I will not reveal the password in clear text (anywhere in the script) that will be great We are mentioning in clear text $passwd ="abc123" .I think there must be a way where I can declare $passwd="GHYFtg56" where decrypt(GHYFtg56) = abc123 I hope I made my question clear

If a function decrypt(GHYFtg56) were possible crypt() would be useless for storing passwords as anyone else (including the attacker) could do the decyphering too. You would have won nothing by storing it as "GHYFtg56".

cryptographic hash function must have the property that it is easy to create the hash (i.e use crypt()) but impossible to do the inverse (i.e. decrypt()) in acceptable time.

In other words: Your script needs to know some password to do something. Whatever the script knows, everyone with access to the script can find out too. The only exception is if the script stores the information somewhere else. See my other post here for a possible method

If you just want to obfuscate it a little (in case you have to open the file in front of untrustworthy people), I suggest to use a combination of map, ord, and chr. You have to first create a test script and run the password through some ord's and chr's to get an obscure string. Then, reverse the previous algorithm and place it in your script. I would give you an example of how I did this but it is not with me right now. :(