Hello, Daniel,

My colleague, Yoan, is currently out of office so I will be assisting you with this case.

Thank you for providing the PDF encrypted by iText with AES256. Indeed, I can confirm that it opens with the default viewer on an iPhone. That is why I have logged it in our feedback portal by creating a public thread on your behalf. You can cast your vote for the item, track its progress, subscribe for status changes, and add your comments on the following link:

PdfProcessing: Encrypted documents with an AES-256 algorithm are opened as empty documents on Apple devices

I have also updated your Telerik points.

Currently, the possible solution that I can suggest is to use AES-128 encryption once the feature is officially released. Stay tuned.

Regards,
Dess | Tech Support Engineer, Principal
Progress Telerik

Hello Matt,

We are open to reviewing and considering AES-256 encryption for Apple devices. If you are indeed able to encrypt a PDF file using iText that successfully opens on Apple devices, could you please share a sample document generated with iText? We’d like to test and examine it to determine whether there are any differences that enable compatibility on Apple devices.

Since this is a public thread and any shared resources are publicly accessible, I recommend opening a separate support ticket specifically for the AES-256 encryption topic. This will allow you to attach the file securely while keeping discussions organized and avoiding confusion.

Additional Information

We've had several similar reports so far. To be honest, the situation with AES256-encrypted PDFs on Apple devices is a bit tricky. PDF documents encrypted with AES-256 often open as blank pages in the default viewer on Apple devices (like iPhones and iPads) due to limited support for advanced encryption standards in Apple's native PDF rendering tools. [ReadMore]

What is the Reason?

Limited AES-256 Support in Native Viewers
Apple's built-in PDF viewers (such as Preview, Safari, and Books) do not fully support AES-256 encryption, especially when combined with certain PDF features like OTP protection or advanced permissions. This results in blank pages or failed rendering.

PDFKit and Preview Limitations
Apple's PDFKit (used in iOS/macOS for rendering PDFs) lacks compatibility with some newer PDF standards and encryption schemes. It may ignore or fail to process:

• Adobe-specific features (e.g., AcroJS scripts)
• Certain image formats (e.g., JPEG2000)
• Complex permissions or metadata
• [Read More]

Rendering Bugs in iOS Versions
Some iOS versions (e.g., iOS 18.2) have known bugs where PDFs display incorrectly. Images may be missing or inverted, and encrypted content may not render at all. [Read More]

App-Specific Behavior
Even Adobe Acrobat Reader on iOS may struggle with AES-256 encrypted PDFs unless the file is saved locally and opened directly in the app. Cloud-based workflows or "Open In" options often fail. [Read More]

Regards,
Yoan
Progress Telerik

Hello Matt,

Thank you very much for providing the additional details and thoughtful feedback. I want to assure you that everything you’ve shared will be thoroughly reviewed and carefully considered during the planning phase, before any work on this task begins.

Regards,
Yoan
Progress Telerik