Above code contained a couple of spelling misstakes, which I've taken the liberty of correcting.

Also, is there a way to get this approach to work with an arbitrary length plaintext? I.e. with plaintexts more than 16 character in length?

# Encrypter

use Crypt::Blowfish ();
use MIME::Base64 qw( encode_base64 );

my $key       = ...;
my $plaintext = ...;
die("Text to encrypt must be less than 16 bytes long\n")
   if length($plaintext) >= 16;

my $cipher = Crypt::Blowfish->new($key);
my $padded_plaintext = pack('Ca15', length($plaintext), $plaintext);
my $ciphertext1 =                $cipher->encrypt(substr($padded_plain
+text, 0, 8));
my $ciphertext2 = $ciphertext1 ^ $cipher->encrypt(substr($padded_plain
+text, 8, 8));
my $ciphertext  = $ciphertext1 . $ciphertext2;
my $websafe_ciphertext = substr(encode_base64($ciphertext, ''), 0, -2)
+;

# Decrypter

use Crypt::Blowfish ();
use MIME::Base64 qw( decode_base64 );

my $key                = ...;
my $websafe_ciphertext = ...;
die("Text to decrypt must be exactly 22 bytes long\n")
   if length($websafe_ciphertext) != 22;

my $cipher = Crypt::Blowfish->new($key);
my $ciphertext = decode_base64($websafe_ciphertext.'==');
my $ciphertext1 = substr($ciphertext, 0, 8);
my $ciphertext2 = substr($ciphertext, 8, 8);
my $padded_plaintext = $cipher->decrypt(               $ciphertext1)
                     . $cipher->decrypt($ciphertext1 ^ $ciphertext2);
my $plaintext = unpack('C/a*', $padded_plaintext);
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