Password Protection of PDF with multiple passwords stored in external database.

Question

Ok, here is what I need to do.
I need to find a way to embed a script into a PDF using LifeCycle Designer so if someone downloads my PDF they won't be able to access it unless they are a registered user in my MSAccess or MySQL database.
Link from PDF to external database to authenticate USER before allowing the PDF to be opened (in case they have downloaded it to their desktop).
Is there a creative way or alternative to accomplish this? Just looking to prevent the average person (not the security savy webmaster).
Thank you.

Answer 1

The Bouncy Castle JCE provider (www.bouncycastle.org) has Base64 encoder/decoder classes that 'just work'.
import org.bouncycastle.util.encoders.Base64;
String base64encodedString = "ABCKD4632adcomd";
byte[] decoded = Base64.decode(base64encodedString);
String reencoded = new String(Base64.encode(decoded));As for your second question re: how should you re encrypt the passwords? The standard, quite secure way of doing this is to use a one-way cipher. This will encrypt the password text to an unintelligible mess, that CANNOT be decrypted back to the original.
When a new user enters their password for the first time, you use your cipher to encrypt it, and store this (not the actual password).
To verify this user, you take the password they give you, encrypt it in the same way, and compare the results.
Unix/Linux can use a shell command called 'crypt' to do exactly this... MySQL will also do it for you... INSERT INTO blah VALUES(CRYPT('blahpasswordstring'), and SELECT * FROM blah WHERE password=CRYPT('enteredpassword')).
... and its far too early in the morning, and I cant for the life of me remember the JCE equivalent of this function :(