I think your main problem might be that you aren't using the Crypt::CBC module. Here is an example program which encrypts and decrypts a file using Blowfish:

#!/usr/bin/perl

use strict;
use warnings;

use Crypt::CBC;

run();

sub run
{
    my $cipher = Crypt::CBC->new( {'key'             => 'my secret key
+',
                                   'cipher'          => 'Blowfish',
                                   'iv'              => '$KJh#(}q',
                                   'regenerate_key'  => 0,   # default
+ true
                                   'padding'         => 'space',
                                   'prepend_iv'      => 0,
                                   'pcbc'            => 1  #default 0
                                  });

    encrypt_and_decrypt_strings($cipher);
    encrypt_file($cipher);
    decrypt_file($cipher);
}

sub encrypt_and_decrypt_strings
{
    my $cipher = shift;

    # encrypt and decrypt strings
    my $ciphertext = $cipher->encrypt("This data is hush hush");
    my $plaintext = $cipher->decrypt($ciphertext);
    print("decrypted plaintext = $plaintext\n");
}

sub encrypt_file
{
    my $cipher = shift;

    print "encrypting file...\n";
    my $plain_file = "BIG_FILE";
    my $enc_file = "BIG_FILE.encrypted";
    open OUTFILE, ">$enc_file" or die "can't open $enc_file: $!";
    my $buffer;
    $cipher->start('encrypting');
    open(F,"$plain_file") or die "can't open $plain_file: $!";
    while (read(F, $buffer, 1024))
    {
        print OUTFILE $cipher->crypt($buffer);
    }
    print OUTFILE $cipher->finish;
    close F;
    close OUTFILE;
    print "finished encrypting file\n";
}

sub decrypt_file
{
    my $cipher = shift;

    print "decrypting file...\n";
    my $enc_file = "BIG_FILE.encrypted";
    open INFILE, "<$enc_file" or die "can't open $enc_file: $!";
    my $dec_file = "BIG_FILE.decrypted";
    open DECFILE, ">$dec_file" or die "can't open $dec_file: $!";
    $cipher->start('decrypting');
    my $buffer;
    while (read(INFILE, $buffer, 1024))
    {
        print DECFILE $cipher->crypt($buffer);
    }
    print DECFILE $cipher->finish;
    close DECFILE;
    close INFILE;
    print "finished decrypting file\n";
}

__END__
[download]