Yes, you could do this with the openssl toolkit. You want the "enc" option. See this page for details.

On the other hand, this would require either calling out to the /whatever/bin/openssl command, or using the OpenCA::OpenSSL module, which does pretty much the same thing. (if it even supports the "enc" function)

The Crypt::Blowfish_PP perl module would seem to be a simpler option if you are already processing the cgi request in perl.

From the docs:

$blowfish=new Crypt::Blowfish_PP($key); 
$plaintextBlock=$blowfish->decrypt($ciphertextBlock);
[download]

That's pretty lucid for your needs, eh ?