17 Replies Latest reply on Mar 20, 2013 12:30 PM by IsakTen

    Read-only AND Encrypted

    FormUser

      I am using Acrobat XI Pro: is there a way to make a file read-only AND encrypted?

        • 1. Re: Read-only AND Encrypted
          Test Screen Name Most Valuable Participant

          All security uses encryption, but what exactly do you mean by "read only"? What do you want to forbid?

          • 2. Re: Read-only AND Encrypted
            FormUser Level 1

            PDF/A = read-only, looking for a way to make it work with encryption.

            • 3. Re: Read-only AND Encrypted
              Test Screen Name Most Valuable Participant

              I see what you mean. But PDF/A isn't really read only, that's just a quirk of Acrobat and it can be turned off. It was never created as a form of protection. Crucially, though, the rules of PDF/A forbid encryption, there cannot be a workaround. Encrypting - limiting access - isn't within the archiving aims.

              • 4. Re: Read-only AND Encrypted
                FormUser Level 1

                I disagree that PDF/A is a quirk. It is a regular feature found in ‘Save As Other…’ PDF/A is in routine use by at least one Government agency that I know, to prevent modification. Of course it is still possible for a hacker to modify the file by saving to a different file format and other hacking methods, but by then the modification is apparent.

                 

                In any case, this is a red herring, I mentioned PDF/A as an example for a read-only format, it does not have to be PDF/A as the read-only format.

                 

                What I am after is how to make an Acrobat file that is read-only AND encrypted, see subject line and my original posting.

                • 5. Re: Read-only AND Encrypted
                  Dave Merchant MVP & Adobe Community Professional

                  Test Screen Name doesn't mean that PDF/A is a quirk, but that the way Acrobat makes all PDF/A files into read-only documents is. Adobe interpret the ISO standard to imply that PDF/A files should not be modified, hence they stop you from doing so. Other software vendors disagree.

                   

                   

                  FormUser wrote:

                   

                  What I am after is how to make an Acrobat file that is read-only AND encrypted, see subject line and my original posting.

                   

                  Applying regular encryption to the file with the permissions settings to "no changes", you get exactly that.

                  • 6. Re: Read-only AND Encrypted
                    FormUser Level 1

                    "Applying regular encryption to the file with the permissions settings to "no changes", you get exactly that."

                     

                    Sorry, I disagree with that too. The intended recipient can upload the file to any of the on-line pdf editors, for example, enter the ‘Document Open’ password, and he will be able to edit the file in spite of a ‘No Change’ settings set with a different ‘Permission’ password.

                     

                    In other words, "applying regular encryption to the file with the permission settings to "no changes"[sic]" will only encrypt the file, but does not make the file 'read-only'. I do not want the intended recipient to be able to edit the file, at least not THAT easy.

                    • 7. Re: Read-only AND Encrypted
                      Test Screen Name Most Valuable Participant

                      As Acrobat's warning message says, not all software respects security permissions. The only way around that is to use a security method that cannot be opened except by Acrobat, such as the DRM offered by LiveCycle Rights Management. Quite a heavyweight solution.

                       

                      Alternatively, if you want to be able to detect modification, then you can simply use digital signatures.

                       

                      I don't quite understand what you are getting at. On the one hand, PDF/A seems enough security for your example, even though it can readily be taken off and put back on, and isn't even meant for security. On the other hand, you aren't interested in Acrobat's actual security options.


                      Perhaps you could describe your precise needs/wants, rather than just using the phrase "read only" which is not very well defined.

                      • 8. Re: Read-only AND Encrypted
                        FormUser Level 1

                        Thanks for asking about the actual application, which is emailing contractual documents. The recipient should only be able to printout and sign. Any changes to the document are made by hand and initialized, just like on paper. The vast majority of recipients are not very computer-savvy, I cannot expect anything more from them beyond entering a password to open the document. But a few recipients may be computer-savvy, and I want to prevent them from hacking any difficult-to-detect changes to the document.

                        • 9. Re: Read-only AND Encrypted
                          Dave Merchant MVP & Adobe Community Professional

                          If you want people to electronically-sign a document without any possibility of them altering the underlying page content prior to signing, use Adobe EchoSign. They don't get access to the original PDF file until it's been certified (after all parties have placed their signatures), at which point any changes are detectable as they will invalidate the certificate hash.

                          • 10. Re: Read-only AND Encrypted
                            FormUser Level 1

                            I think that just explaining the EchoSign procedure would turn potential clients off, it is too dissimilar from a paper procedure. Personally, I myself certainly do not like signing a proxy.

                             

                             

                            Returning to the original issue: emailing password-protected contractual documents has become commonplace, it is not an problem.

                             

                             

                            The problem is to prevent difficult-to-detect changes to the contractual document. The read-only of PDF/A would be adequate. Of course, it is possible to hack PDF/A, but it would be easy to detect that the PDF/A has been hacked, so that is not a problem either.

                             

                             

                            The overall issue is thus to combine read-only (if not PDF/A, then something else) and password protection. I am still looking for such read-only/password protection combination.

                            • 11. Re: Read-only AND Encrypted
                              George_Johnson MVP & Adobe Community Professional

                              Since you posted to the Security & Digital Signature forum, have you considered using digital signatures? You can make it so the document is locked when signed and can detect if the document was subsequently changed in any way.

                              • 12. Re: Read-only AND Encrypted
                                FormUser Level 1

                                George and others, I may indeed be missing something about digital signatures. Let me explain the intended workflow step-by-step, and please tell me what I am missing, thanks!

                                 

                                Step 1: I email a password-protected contract document with two signature blocks, a first signature block for the client, and a second signature block for myself. Both signature blocks are blank. (The password has been previously agreed to)

                                 

                                Step 2: Client enters the password to open and print the document, and signs the first signature block. Client may manually make and initialize minor changes. Client faxes (or mails) the document back to me. Or, if the client is computer-savvy enough, client scans, encrypts the document with the same password, and emails the document back to me.

                                 

                                Step 3: I countersign the second signature block, scan, encrypt the document with the same password, and email the document back to client.

                                 

                                My concern is about what could happen in step 2. How do I prevent difficult-to-detect changes to the document? Easy-to-detect changes to the document are of no concern to me, I simply refuse to countersign. But difficult-to-detect changes in the course of a normal office workday are a different matter entirely.

                                 

                                Sorry, BTW, if the above workflow appears archaic to Adobe forum participants. The vast majority of the biz world is still THAT archaic with only a few inroads of hi-tech.

                                • 13. Re: Read-only AND Encrypted
                                  FormUser Level 1

                                  Folks,

                                   

                                   

                                  I may have found a way to create a pdf document with Acrobat XI Pro that is read-only AND encrypted. Please let me know if I have indeed succeeded or not, thank you!

                                   

                                   

                                  The steps that I follow to create the read-only AND encrypted pdf document are as follows:

                                   

                                   

                                  Create a plain pdf document, from MS Word for example

                                  Sanitize Document

                                  Create Form without fields

                                  Close Form Editing

                                  Encrypt with Password

                                  Save

                                  Save As Other… => Reader Extended PDF... => Enable More Tools (includes form fill-in & save)…

                                   

                                   

                                  I as a not-very-sophisticated-computer-user did not find a way to hack difficult to detect changes - such as the insertion or deletion of the word 'not' - into the resulting pdf document. But again, please let me know if you DO find a way to hack the resulting pdf document, thank you!

                                   

                                   

                                  P.S. I think the resulting pdf document is essentially an encrypted form, albeit one without fields.

                                  • 14. Re: Read-only AND Encrypted
                                    Dave Merchant MVP & Adobe Community Professional

                                    OK, completely lost now.

                                     

                                    Your workflow in reply 12 is crying out for digital signatures or EchoSign - that's the reason they were invented, nobody should be printing and re-scanning a PDF file these days.

                                     

                                    Your explanation in reply 13 makes no sense whatsoever - starting and stopping the Form Edit mode without creating any fields does nothing to the PDF file. A PDF form is by definition a file with one or more form fields on it. Form fill-in Reader Extension is meaningless if there are no fields present, and if they are printing and re-scanning the document there's no point in applying REs in the first place.

                                    • 15. Re: Read-only AND Encrypted
                                      FormUser Level 1

                                      Dave:

                                       

                                       

                                       

                                      On your remark to reply 12: it is a human issue, not a hi-tech issue. For the vast majority of people that I am dealing with, nothing replaces a wet ink signature on a $$ contract, and on a $$$ contract even witnessed with another wet ink signature. I put this to rest, it is besides the topic in the subject line of this thread which is 'read-only AND encrypted pdf files'. Thus, I continue...

                                       

                                       

                                       

                                      On your remark to reply 13: the stated method does in fact do something to the pdf file. Before the method has been applied, a plain pdf file can be easily edited, but after the method has been applied, the resulting pdf file cannot be edited with ‘Edit Text & Images’ in Acrobat XI Pro. Moreover, a couple of on-line pdf editors that I tried could only do very coarse edits that are easy to detect, such as deleting/swapping pages, adding stickies, and the like, but the on-line pdf editors could not edit the text of the document, in particular.

                                       

                                       

                                      Don't look at the RE labels and what not, do look at the resulting pdf file after the method stated in reply 13 has been applied.

                                       

                                       

                                       

                                      If you (or somebody else) are in some way able to edit the text of the resulting pdf file after the method stated in reply 13 has been applied, let me know, thanks!

                                      • 16. Re: Read-only AND Encrypted
                                        Dave Merchant MVP & Adobe Community Professional

                                        Simple: de-extend the file in Acrobat Pro using File > Save a Copy, then remove the permissions password (trivial even if you don't know what it is).

                                         

                                        FormUser wrote:

                                         

                                         

                                        If you (or somebody else) are in some way able to edit the text of the resulting pdf file after the method stated in reply 13 has been applied, let me know, thanks!

                                         

                                        Applying Reader Extensions signs the PDF with a hidden digital certificate, which stops some of the editing features from working - but it can be removed again by anyone, as every copy of Acrobat Pro has the private key. You can do the same thing with the Certify tool and a self-signed digital ID, which is a lot harder to get rid of and can not only restrict editing, but can detect malicious attempts to alter the source of the file. Of course in your case that's meaningless as you're bouncing through a printout.

                                         

                                        To apply Reader Extensions you do not need to open Forms Editing mode. All you're doing is switching the toolbar layout back and forth.

                                         

                                        I appreciate that some people are uncertain about electronic signatures on contracts, but they are perfectly legal in most countries and far more secure than a paper->scan workflow. I really suggest you look at Adobe EchoSign, it's free to try and very easy for people to use. It even supports a fax-back service for those who refuse to sign on screen.

                                        • 17. Re: Read-only AND Encrypted
                                          IsakTen Level 4

                                          You can also apply a digital (certificate-based) signature. This will not prevent modification but if a document is modified the signature status will be invalid.