my $cipher = Crypt::CBC->new( -cipher => 'Rijndael'
                            , -key   => $key
                            , -iv    => $iv
                            , -regenerate_key  => 0
                            , -padding         => 'space'
                            , -prepend_iv      => 0
                            );

my $buffer;
my $tmpfile = 'somefile';
open(FH_crypted, "<$tmpfile");
binmode FH_crypted;
open(FH_decrypted, ">$tmpfile.good");
binmode FH_decrypted;
$cipher->start('decrypting');
while (read(FH_crypted,$buffer,1024)) {
      print FH_decrypted $cipher->crypt($buffer);
  }
print FH_decrypted $cipher->finish;
$cipher->finish;
close FH_crypted;
close FH_decrypted;