To ensure that your PDF documents and their valuable contents are secured, you need to ensure that they are encrypted and that use is restricted. However, if you encrypt a PDF document with a password, you may find that is not as protected as you might think.
This is because the password that you enter is used as the key and the implementation of the Adobe Security Handler (which does the encryption) works is not very effective. Many password recovery programs take advantage of this and enable users to remove PDF passwords and therefore the encryption. Once the document open password has been removed any PDF restrictions applied to stop editing, printing, etc. can be removed in seconds.
Besides security issues, there are other problems involved when managing the key (password) in an encrypted PDF document. These include:
- Making the key and writing it down
- Transferring the key to the authorized user
- Setting PDF restrictions
- Altering user rights
- Preventing unauthorized transfer or theft of the key
In PDF encryption, a key refers to a password that is used to both encrypt and decrypt the PDF file. You have to send the key to the intended or authorized user along with the encrypted PDF document so that they can open it. But the most prominent danger is that when a user gets hold of the password or key, not only can the document be manipulated, it can be shared or forwarded to unintended entities. In this regard, password keys that have to be visibly shared with users are highly unreliable and insecure.
There are different ways to transfer keys to authorized users. In a complex setting, you can create a random cryptographic key at the time of document encryption (so each time you protect the same document it is given a new key). This key must only be made available to the user for its intended purpose. However, if you send the key as a file, the user could easily forward it to others.
Perhaps the key could be hidden in the user registry. However, numerous programs can display what has been changed to find the location and value of the key quickly and this could then be copied and given to others.
Both the above methods are not fail-proof when it comes to PDF security. The right way to secure PDFs files is to lock the key to the authorized user’s device. This will ensure that even if an unauthorized user shares the key with another individual or party it will not work because it is encrypted to the authorized device.
To prevent the theft or transfer of a key, you need to make a note of the following:
- Avoid using passwords
- Do not permit the key to be immediately accessed by the user
- Do not share the key file where the key is instantly recognizable
- Make use of a transparent and secure key exchange mechanism
- Secure the key to each authorized user’s device
When securing PDF files, encryption can be a valuable technology. However, it needs to be implemented in the right manner. Most PDF encryption software uses AES encryption with 256-bit keys but if an attacker can circumvent an encryption system by using simple tools, it does not matter how strong the encryption algorithm is.
To securely protect your PDF files, you require total document protection that can only be provided with the right PDF DRM security system. A robust PDF DRM solution will offer you PDF encryption, licensing controls, public-key technology, and more to safeguard your PDF files from been hacked or compromised regardless of where they reside. With document protection controls from a PDF DRM system, you can:
- Secure, control, and prevent your confidential, classified, and revenue-generating PDF files from been accessed by unauthorized users
- Stop unauthorized sharing and distribution, apply dynamic watermarks with unique user information, and more.
- Maintain full control over how content is used during the entire lifecycle of your documents.
- Stop copying, editing, printing, and any form of manipulation of your PDF documents.
- Enforce expiry controls, revoke access anywhere and at any time, and lock used to devices and locations.
- View where, when, and how often your documents have been viewed and printed and by whom.
PDF encryption that is protected with a password (such as that supplied in Adobe Acrobat) can be easily removed. But with a robust PDF DRM system, you can persistently protect your PDF documents at any time and anywhere.