Posts in Category "Security"

How do I prevent someone from forwarding a PDF?

Attorneys are ethically bound to rigorously defend the confidentiality of clients.

For that reason, legal professionals often want to limit the distribution of documents. Accordingly, I received the following email from at attorney this week:

Is there any way I can prevent someone from forwarding a PDF I send to them?

While it is impossible to prevent someone from forwarding a file, you can prevent the next person from opening it.


Can’t I use passwords?

It is easy to password protect a PDF document. (See Password Security using Adobe Acrobat 8 or 9 ).

Anyone who enters the correct password can open the document. However, that does not prevent the recipient from giving the password to another party who could, in turn, open the document.

Public Key Cryptography

Public Key security is a great way to limit who can open PDF documents. Acrobat uses a mathematical algorithm to create a related pair of keys— a secret private key and a public key.

Public and Private Keys

Public Key security may also be called PKI (Public Key Infrastructure) or Certificate Security.


Here’s how it works in practice:

  1. The parties exchange public keys using Acrobat or Adobe Reader
  2. You encrypt a PDF using the public key of the recipient(s)
  3. The PDF can only be decrypted with the corresponding private key of your intended recipient

Read on to learn how to exchange PDF documents and prevent forwarding.

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Important: Acrobat 9.3 and Acrobat 8.2 Updates Available

Adobe just released updates to both Acrobat and Adobe Reader versions 8 and 9.

Both updates include some bug fixes and critical security updates.

If you manage your own computer, the easiest way to get the update is to choose Help—> Check for Updates.

Close Acrobat after the update begins.

If you don’t manage your computer, please contact your IT department.

You can get more information here about the updates below:

Release Notes for 9.3
Technote 52073
Release Notes for 8.2
Technote 52074
About the Security Updates
Information on Application Security Control
Application Security Wiki

Important: Still using Acrobat or Reader 7?

Adobe no longer supports or patches for Acrobat/Reader 7 and earlier.

These versions and all previous versions are missing critical updates and users are recommended to upgrade.

For more information, see Adobe Support Policies.

NOTE: As described in Adobe’s Supported Product Versions, Adobe Acrobat Professional 7.x and Adobe Reader 7.x support ended on December 28, 2009.

Read on to learn more about why it is important to keep Acrobat up to date.

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Creating a Click-thru Agreement in a PDF

A click-thru (sometimes called ClickWrap) agreement is a software or web-based acceptance of terms.

Click-thru agreements rely on the recipient clicking "OK" or "I agree" to accept the terms of the agreement.

Click thru example

I recently received this email message about Click-thru PDF agreements:

Is it possible to create a message that appears prior to a [PDF] document being opened to accept terms and conditions? If the user would click "Yes" the PDF would open. If the user click "No" the document would close.

Short answer: Yes!

Do Click-thru Agreements have Legal Precedent?

Yes, there are a number legal decisions on the subject.

The earliest reference I found was to ProCD v. Zeidenberg (text), which established that clicking a button in a software program constituted acceptance of terms.

A number of relevant court decisions may be found here: Click-Wrap Agreement – Internet Library of Law and Court Decisions.

In this article, I’ll show you how to create an alert message that pops up when a PDF is opened:

JavaScript Message Window for Click-thru agreement

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Securing Legal Documents – Preso and Resources

On May 24th, my colleague Mark Middleton and I presented a Securing Legal Documents and Information eSeminar.

In the seminar, we covered password, certificate and policy-server security.

Click to see
On-Demand Security eSeminar

(53 minutes)

The presentation was requested by many attendees, so I thought I’d post it here.

I’ve also included a single-page PDF which lists a number of security resources.

Click to get to these documents…

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Custom Security Envelopes

I recently wrote an article on using Security Envelopes to securely send a group of documents to clients.

Security Envelopes can be customized to include your company logo and branding. Essentially, this Acrobat feature is the digital equivalent of pre-printed envelopes.

Customizing the envelope isn’t difficult or necessarily time consuming. Here are the steps involved:

  1. Create the envelope template
    I’ve included a sample envelope in Microsoft Word format
  2. Convert envelope into PDF
  3. Add envelope form fields for To, From, Date, etc.
  4. Set Document Properties
  5. Save into the Acrobat templates folder

Read on to learn how to make your own customized Acrobat Security Envelope using Adobe Acrobat Professional.

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Safely Send Groups of Files using Acrobat Security Envelopes

When you receive a letter in the mail, most of us assume it hasn’t been tampered with by inspecting the seal or looking for suspicious markings. The outside of the envelope tells us who sent the materials. The envelope itself may contain several documents, but we don’t know which ones until we open the envelope itself.

Unfortunately, in the digital world, securely packaging several documents is more complex.

One possibility is to create a zip archive of the files. Zip archives compress the files, but unfortunately can also contain viruses. Today, many anti-spam programs block zip files. Zip archives also don’t tell us what’s inside and if we should open it. Worse, many clients don’t know how to work with Zip files.

An Acrobat Security Envelope is an excellent alternative. A PDF acts as a secure container to send files to your client.

Since Acrobat files can contain attachments, Acrobat can be used as a container for other types of files.

Acrobat 7 offers the ability to create a digital facsimile of an envelope containing other files:
Example Security Envelope

Since the file is an ordinary PDF, all your client needs is the free Adobe Reader to open the file.

Read on to learn how to create a Security Envelope

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Password Security using Adobe Acrobat 8 or 9

Not long ago, I met an attorney who specialized in family law, especially divorce cases. The attorney had an issue come up with a client and wanted to know more about Acrobat security.

His client, the wife in the divorce proceedings, worked two jobs and had a hectic schedule. Email communication would have been the likely solution; however the husband and wife still resided in the same home and shared the same computer and email account.

What to do?

Sensitive matters make for concerned clients. Using Adobe Acrobat security, it is easy to password protect files from prying eyes.

All communications to the client were sent as encrypted PDFs which required a password to be viewed. This offered his client a high level of confidence that the spouse would not be able to open and read information sent from his office.

Read on to learn how to apply and work with password security.

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