Package != Module != Object class

perlmod perlmodlib perlmodstyle perlboot

Your code suggests that you really want to just use a module for library routines, rather than to create an object class... you're pretty much ignoring the point of object-oriented programming by having your methods try to create disposable objects to perform single operations (and you're not storing the results of CreateEncryptDecryptObject, so it's a no-op, anyway.) Further, if your methods were actually invoked through objects, they'd have the object itself as the first item in @_, meaning that, as written, your Encrypt and Decrypt methods, would be trying to encrypt and decrypt the object reference. (And your uses of $log are going to fail... they'll be trying to use $Config::Confmanager::log which will be undefined.)

How you would use these in a program would depend on whether you go with OOP or not.

Here's one easy way with a closure and an ordinary, non-object-oriented module:

package Config::Confmanager;
use warnings;
use strict;
require Exporter;
our @ISA = 'Exporter';
our @EXPORT=qw(Encrypt Decrypt);
use Crypt::CBC; #CPAN Module For Encryption And Decryption  

{
    my $crypto = Crypt::CBC->new( {'key'       => 'passport',
                   'cipher'          => 'DES',
                   'iv'              => '$KJh#(}q',
                   'regenerate_key'  => 0,   # default true
                   'padding'         => 'space',
                   'prepend_iv'      => 0
                   });
    sub Encrypt { 
    my($encryptstring) = @_;
    my $cipherencryptstring = $crypto->encrypt($encryptstring);
    die "Could not Encrypt requested string" unless $cipherencryptstri
+ng;
    return $cipherencryptstring;
    } 

    sub Decrypt {
    my($decryptstring) = @_;
    my $cipherdecryptstring = $crypto->decrypt($decryptstring);
    die "Could not Decrypt requested string" unless $cipherdecryptstri
+ng;
    return $cipherdecryptstring;
    }
}

1;
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And here's how you'd use it.

#!/usr/bin/perl

use strict;
use warnings;
use Config::Confmanager;

my $cleartext = "la dee dah";
my $encrypted = Encrypt($cleartext);
my $decrypted = Decrypt($encrypted);

print "$cleartext\n";
print "$encrypted\n";
print "$decrypted\n";
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(I agree with tilly about @EXPORT_OK, but didn't change it in this example to keep it just a little closer to your original.)