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Hacking Apps

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2011-01-10 21:41:00
pdfer
Registered: Dec 23 2010
Posts: 28

I have seen advertised on different websites offering for sale different apps claiming to be able to remove Security Passwords. Is this true? Anyone know anymore? It sounds scary. We set passwords to protect the document so someone can not easily remove our passwords and enter and cannibalize our works. What do you know. I would appreciate some opinions. Thanks all.

Jackson C.

My Product Information:
Acrobat Pro 9.0, Macintosh
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2011-01-10 22:14:59
#1
UVSAR
Expert
Registered: Oct 29 2008
Posts: 1357
"Permissions" passwords that control printing and copying can be removed from a PDF file trivially - only Adobe software guarantees to respect the restrictions imposed by a permissions password policy, which is why there's a warning message when you apply them. By definition if you can read the content on your screen, your computer knows enough to print or copy the file. It's only honesty on the part of the software reading the PDF which stops you.

"Open" passwords are extremely difficult to defeat unless the password is guessable - software which claims to crack those passwords does so using brute-force, trying every possible character combination, so a file protected with "123" will be broken in seconds, one using "buOf(fgIf68F68r68riVI%7c57y##vt^*cr68$6ghf68r" will take a little longer! With AES-256 encryption and a complex password the average single-CPU time to locate the key runs into billions of years.

If you need to distribute a file of significant value, that everyone can open freely but which prevents some types of extraction, then you must use a security method which restricts the file to being opened in products that will respect the rules; for example using LiveCycle DRM, or distributing it as a protected ebook via Adobe Digital Editions, etc.. It's a compromise between flexibility for your users, cost of implementing the protection, and losses should your works be infringed. Although strong-limit models were popular in the past, the digital media sector now understands that for mass-market sales an open model is better financially; which is why online stores are selling MP3 music tracks instead of DRM-protected ones.

To that end, permissions "security" serves a valid purpose in telling your readership that you don't want them to copy the content. Even though they can bypass it should they wish, the majority of people will get the message. Those that are determined to copy it will do so whatever you try, and that's what the courts are for.
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