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18 lines
708 B
Markdown
18 lines
708 B
Markdown
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Frequently Asked Questions
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Why Don't You Support Writing a PDF File with Encryption?
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PDF encryption offers very little protection:
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- PDF encryption keys are reused and derived from the user password (padded
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with a standard base string) and the object numbers in the file.
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- RC4 encryption (40- and 128-bit) was broken years ago.
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- AES encryption (128- and 256-bit) is better, but PDF uses Cipher Block
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Chaining (CBC) which enables attacks that allow the original encryption key
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to be recovered.
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In addition, PDF usage controls (no print, no copy, etc.) are tied to this
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encryption, making them trivial to bypass.
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