Here is a running version of your code, with a legitimate key. It takes your values, makes a token, then decrypts the token. Can you describe in more detail what you need with the padding? Here is a commonly used sub for padding. Substitute your padding for the null bytes "\0", with a similar length($data) method.

sub get16 {
    my $data = shift;
#    return "\0" x ( 16 - length($data) % 16 ) . $data;
     return $data . "\0" x ( 16 - length($data) % 16 );

}
[download]

Here is your code, working with a legitimate key with debugging steps along the way.

#!/usr/bin/perl
use warnings;
use strict;
use Crypt::Rijndael;

my $key = "1A2B3C4D5E6Fabcd";
#$key = pack("H*",$key);

print "$key\n";

my $crypt = Crypt::Rijndael->new( $key, Crypt::Rijndael::MODE_ECB() );

my $vers = 1;
my $rand = 1002247;
my $time = 1317072992;
my $empid = 123;
my $sum = 103;
my $ndid = 42; 

my $packed = pack( "CLLLC", $vers, $rand, $time, $ndid, $sum );
print "$packed\n";

my @unpacked =  unpack("CLLLC",$packed) ;
print "@unpacked\n";


my $token = $crypt->encrypt($packed^("\0"x16));
print "\n$token\n";

$token = unpack("H*",$token);

print "---------+---------+---------+--\n";
print $token,"\n";


# do decryption
my $z = pack("H*", $token);
print "$z\n";

my $cbc1 = new Crypt::Rijndael $key, Crypt::Rijndael::MODE_CBC;
my $decrypted = $cbc1->decrypt($z);
print "decrypted->$decrypted\n";

my @values =  unpack("CLLLC",$decrypted) ;
print "@values\n";


exit;
[download]

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