[Gllug] Encrypted PDF

[Daniel P. Berrange]

On Fri, Feb 24, 2006 at 06:25:03PM +0000, Richard Jones wrote:
> 
> This is an encrypted PDF file:
> 
> http://www.annexia.org/tmp/patent.pdf
> 
> (Yes, it's actually a software patent which I was partly responsible
> for .. hiss boo!)
> 
> evince (GNOME PDF reader) claims the document is encrypted and
> requires a password which I don't know.  xpdf displays page 1 but it
> seems that pages 2-81 are all blank.  Presumably they're the encrypted
> pages.
> 
> Does anyone know if it's possible to crack PDF encryption?  Is it a
> non-serious obfuscation like the passwords on Office documents, or is
> it proper encryption?

http://www.password-crackers.com/crack/guapdf.html

"(Un)fortunately, another method to decrypt PDF files exists. PDF 
 security (including Acrobat 3.x, 4.x scheme and Acrobat 5.x-7.x 
 40-bit encryption) uses strong enough encryption algorithm, but 
 because of U.S. crypto export regulations the key length is only 
 40 bits. So, you need to test only 240 keys to decrypt your file 
 with guarantee. GuaPDF does it, and key testing will take about 
 12 days on the Pentium 4/1600 PC. Within this time (and in average 
 within the half of this time) ANY file, encrypted with ANY password 
 (no matter what length of the password is or what language or 
 symbols used, etc) can be decrypted."


Regards,
Dan.
-- 
|=-            GPG key: http://www.berrange.com/~dan/gpgkey.txt       -=|
|=-       Perl modules: http://search.cpan.org/~danberr/              -=|
|=-           Projects: http://freshmeat.net/~danielpb/               -=|
|=-   berrange at redhat.com  -  Daniel Berrange  -  dan at berrange.com    -=|
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