Planet PDF Forum Planet PDF Forum
  New Posts New Posts RSS Feed - pdf password asked by reader
  FAQ FAQ  Forum Search   Register Register  Login Login


Hi, welcome to the Foxit Planet PDF Forum. If you have PDF or Adobe Acrobat questions then the right place to ask them is here, in this forum.

pdf password asked by reader

 Post Reply Post Reply
Author
ylard View Drop Down
New Member
New Member


Joined: 26 Mar 2012
Location: brussels
Points: 1
Post Options Post Options   Quote ylard Quote  Post ReplyReply Direct Link To This Post Topic: pdf password asked by reader
    Posted: 26 Mar 2012 at 10:34am
hi,
I am working on archiving of digital data. When archiving pdf, I must ensure that the files are viewable in a long term period. So I want identify files requiring passwords in order to advice the producer to remove the password. But, I do not know how to identify when Arcobat  reader (or others Pdf readers) sometimes requires password to view files and sometimes does not.
I have two files with /Encrypt set
If I look at the in the 'encryption object' , one has
 
<</Filter /Standard
/V 2
/Length 128
/R 3
/P -20

/O and /U are set

and acrobat reader ask for a password (even if the file should be printable as bit 3 is set in /P)

and the othe rone

<</P -44
/Filter /Standard
/R 2
/V 1

 /O and /U are also set

but for this one, no password is required by acrobat reader.

My questions:
- why acrobat reader do not let see printable documents?
- How can I identify files which will require passwords in  Acrobat reader?

thanks for any answer







Back to Top
Sponsored Links


Back to Top
aandi View Drop Down
Senior Member
Senior Member


Joined: 07 Jul 2011
Points: 18358
Post Options Post Options   Quote aandi Quote  Post ReplyReply Direct Link To This Post Posted: 26 Mar 2012 at 11:37am
The "printable" permission and "needs a password" are quite separate things. Have you read the PDF Specification where it talks about encryption?

Especially, 7.6.3.1 "PDF’s standard security handler shall allow access permissions and up to two passwords to be specified for a document".

I recommend you experiment with using Acrobat to actually set security to see the huge range of variations available.


Edited by aandi - 26 Mar 2012 at 11:41am
Back to Top
aandi View Drop Down
Senior Member
Senior Member


Joined: 07 Jul 2011
Points: 18358
Post Options Post Options   Quote aandi Quote  Post ReplyReply Direct Link To This Post Posted: 26 Mar 2012 at 12:27pm
Notice too that /O and /U are required, even though the passwords are optional.
Back to Top
aandi View Drop Down
Senior Member
Senior Member


Joined: 07 Jul 2011
Points: 18358
Post Options Post Options   Quote aandi Quote  Post ReplyReply Direct Link To This Post Posted: 26 Mar 2012 at 12:46pm
I had to reread this stuff, I couldn't remember how it worked when passwords were absent. But this is there. Some more thoughts:

- some versions of Acrobat allowed you to create a PDF with neither owner nor user password, current versions do not.

- the algorithms are designed so that a casual inspection does not tell you anything about passwords, including whether or not they exist.

- a PDF reader needs to know whether to prompt for user password. How? See 7.6.3.4 "Note too that algorithm 6 can be used to determine whether a document’s user password is the empty string, and therefore whether to suppress prompting for a password when the document is opened."
Back to Top
Lejeckey View Drop Down
New Member
New Member
Avatar

Joined: 09 Aug 2014
Points: 1
Post Options Post Options   Quote Lejeckey Quote  Post ReplyReply Direct Link To This Post Posted: 10 Aug 2014 at 7:47am
I had problem too
Back to Top
sohapearl View Drop Down
New Member
New Member


Joined: 16 Sep 2014
Points: 1
Post Options Post Options   Quote sohapearl Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 2014 at 1:15pm
as i said i can not copy it into another place, if i copy it to other place any pdf file will be corrupted. nothing problem when i open it from dvd directly



Edited by sohapearl - 16 Sep 2014 at 1:15pm
Back to Top
aandi View Drop Down
Senior Member
Senior Member


Joined: 07 Jul 2011
Points: 18358
Post Options Post Options   Quote aandi Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 2014 at 3:19pm
As you said where? This seems to be your first post. And it doesn't seem to be connected to the discussion here from a couple of years ago. I wonder if you meant this to go somewhere else. 
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 11.10
Copyright ©2001-2017 Web Wiz Ltd.

This page was generated in 0.016 seconds.