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Portable Document Format (PDF) is a popular file format to store documents. Protection of PDF files is thus important. In this paper, we present a (t, n) PDF-sharing scheme which shares the given secret PDF file F among n stego-PDF files. Each stego-PDF file looks completely identical to its original PDF version. When people collect sufficient number (t) of stego-PDF files among the n created stego-PDF files, the secret PDF file F can be revealed error-freely, while less than t stego-PDF files gets nothing but noise. Therefore, our protection not only tolerates missing, but also resists thief's peeping. As a result, the scheme provides the readers a different approach to the protection of important PDF files, in a manner quite distinct from the watermark or encryption approaches used by commercial PDF makers.

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