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Old 09-27-2025, 04:57 PM   #6
Doitsu
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Device: Kindle PW2
Quote:
Originally Posted by Abdo View Post
  • The EPUB contains audio elements (so PDF conversion isn't suitable)
You can embed or attach audio files to PDF documents.

Quote:
Originally Posted by Abdo View Post
  • Are there EPUB-specific features (like FXL - Fixed Layout) that make modification more difficult?
It's slightly off-spec, but you could theoretically obfuscate the first 1040 bytes in all files, except for the .opf file. But that obfuscation could be easily reverted. It'll also trigger the following EPUBCheck error message for all non-font files:

Code:
ERROR(PKG-026): obfuscation_test.epub/META-INF/encryption.xml(24,58): Obfuscated resource must be a Font Core Media Type (was declared as "XXX/XXX" in "OEBPS/content.opf").
My test file displays fine in Thorium, ADE 4.5 and Calibre E-Book Viewer, but it can no longer be edited with Sigil, because all .xhtml, .css, .png and .ttf files have been obfuscated.
Attached Files
File Type: epub obfuscation_test.epub (53.1 KB, 4 views)

Last edited by Doitsu; 09-28-2025 at 03:48 AM.
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