Improving Acrobat Security ?

Question

Acrobat provides an easy means for the password protection of PDF documents. The approach is advantageous in that the documents can be read with the freely available Adobe Reader with usage of the appropriate passwords. Unfortunately, as is well known, this protection is easily circumvented.
My question is this. Is there any way to improve the present Adobe PDF security or does anyone know of a program that will generate an Adobe Reader compatible file after an original PDF file has been encrypted and decrypted by a "third party" program.
We tried this appraoch with the Dlock version of MPJ, which is a military grade encryption system. A PDF file was encrypted and then decrypted by MPJ. Unfortunately, Adobe Reader could not read the resultant decrypted file.The MPJ encryption/decryption process functions properly with other files.
Thank you very much for your assistance.

Answer 1

Hi Dave,
I did find this on the Adobe Acrobat developer site. The SDK does have encryption capability as follows. I still don't know if this can also be accomplished by using a command line option with acrobat.exe.
QUOTE
Encryption is controlled by an encryption dictionary in the PDF file. The Acrobat  core API uses RC4 (a proprietary algorithm provided by RSA Data  Security, Inc.) to encrypt document data, and a standard (proprietary)  method to encrypt, decrypt, and verify user passwords to determine  whether or not a user is authorized to open a document.
Each stream or string object in a PDF file is individually encrypted. This level of encryption improves performance  because objects can be individually decrypted as needed rather than  decrypting an entire file. All objects, except for the encryption  dictionary (which contains the security handler’s private data), are  encrypted using the RC4 algorithm Adobe licenses from RSA Data Security,  Inc. A plug-in may not substitute another encryption scheme for RC4.
A plug-in that implements a security handler is responsible for encrypting the values it places into the encryption  dictionary, and it may use any encryption scheme. If the security  handler does not encrypt the values it places into the encryption  dictionary, the values are in plain text.
The core API provides two Cos layer methods to encrypt and decrypt data using the RC4 algorithm. These methods are CosEncryptData and CosDecryptData. (See the Acrobat and PDF Library API Reference.)
Security handlers may use these methods to encrypt data they want to put into the PDF file’s encryption dictionary  and decrypt data when it is read from the dictionary. Security handlers  may instead choose to ignore these methods and use their own encryption  algorithms.
END QUOTE
Best regards,
Robbie