About PDF Versions
This product supports PDF versions 1.0 to 1.7; this topic summarizes which features are supported in each version. Features not mentioned here are supported in all versions. PDF files created by the product can be from versions 1.3 to 1.7 or PDF/A (based on version 1.4).
Encryption
40-bit RC4 – Supported in PDF version 1.1 and above (security revision 2)
128-bit RC4 – Supported in PDF version 1.4 and above (security revision 3)
128-bit AES – Supported in PDF version 1.6 and above (security revision 3)
256-bit AES – Supported in PDF version 1.7 and above (security revision 3)
All encryption follows RSA norms, and all AES encryption complies with FIPS (Federal Information Processing Standard).
Document permissions
The available set of document permissions depend on the security revision number (defined in the PDF standard). Two security revisions are used: 2 and 3.
Security revision 2 (RC4-40 encryption) allows the document creator to restrict the following operations:
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Modifying the document contents
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Copying text and graphics from the document
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Adding or modifying text annotations and interactive form fields
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Printing the document
Security revision 3 (RC4-128, RC4-128 or RC-256 encryption) adds the following operations to the repertoire the document creator can control:
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Form fill-in and sign document
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Text inspection for accessibility
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Document assembly including insertion, deletion of pages and creation of bookmarks and thumbnails
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Allow only printing that does not allow perfect digital copies, but which may also result in degradation of output quality
Metadata
Metadata fields are supported in PDF version 1.1 and above.
PDF file types
PDF/A : Supported in PDF version 1.4 only
Linearized PDF: PDF version 1.2 and above
PDF/A and Linearized PDF are mutually exclusive options. Also, if the PDF/A option is turned on, all controls in the Password Security panel are disabled.
PDF/A is a standard designed to be usable in as wide a range of applications and operating systems as possible, and also withstand future technological developments.
Linearized PDF is optimized for fast web display, so the first page displays quickly while other pages are still being processed.
Compression methods
TIFF G4 – PDF 1.0 to 1.3
JBIG2 – PDF 1.4
JPEG2000 – PDF 1.5 and above
MRC compression is supported in PDF 1.3 and above, for image-only PDF files.
When a PDF contains many photos, use of JPEG2000 can reduce file size by 50% or more, compared to earlier compression methods, without visibly losing quality.