If you have Adobe Acrobat iOS installed on your device, tapping "Open In" should present a list of apps that includes "Adobe Acrobat Reader" for opening the file. You may have to swipe the list of apps from right to left to see Adobe Acrobat. If this still does not work, please let me know.
That said, there are some forms of encryption and protected documents that the iOS Adobe Acrobat can read, but cannot edit. If you have a sample of one of these files to share, you can email me at firstname.lastname@example.org and I can confirm.
Thanks for the quick response. The problem is that, for these documents, the "Open In..." dialogue does nothing. When clicking the link for any of these protected documents, a new tab opens in Safari with the Open In... link in the upper left, but clicking the button does nothing, unlike other documents, where the list of apps appears. The viewer just seems to choke on these protected docs.
I will email you an example at the address you provided. We are expecting viewer to just view it, not allow editing. The password protection is for editing, not viewing.
Thank you again for reaching out. After seeing your file, I am nearly positive that this is a bug in Safari (since "Open In" does nothing). I will file a bug with Apple.
I have a similar problem. I have several pdf documents signed with a self-signed certificate (created by me from Microsoft Internet Information Server).
I have installed my self-signed certificate in Windows 10 operating system and I open that document without problems. But when I try to open it in Android, IOS (iphone) or Mac OS, I always get the same error: "The file is possible to be damaged or format which Preview View does not be able to recognize" or something like that. I have installed the self-signed certificate in them as well.
I have tested with diferents certificates and pdf versions (when I convert it from a .docx file) and I always get the same result in Android, IOS and Mac OS.
What is the problem? What am I doing wrong?