A Method of Embedding and Extracting Hidden Information Based on English PDF Documents

A technology for hiding information and documents, which is applied in the field of embedding and extracting hidden information based on English PDF documents. It can solve problems such as damage to daily reading operations and saving operations, and difficult extraction of hidden information, and achieve good visual concealment and robust editing behavior. Effect

Active Publication Date: 2016-05-11
SUN YAT SEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Existing information hiding technologies based on PDF documents are easily destroyed by various daily reading operations and saving operations of documents, and the embedded hidden information is difficult to be completely extracted

Method used

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  • A Method of Embedding and Extracting Hidden Information Based on English PDF Documents
  • A Method of Embedding and Extracting Hidden Information Based on English PDF Documents
  • A Method of Embedding and Extracting Hidden Information Based on English PDF Documents

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Embodiment 1

[0051] The method of the present invention embeds information based on the equivalence relationship between characters in the text string and octal sequences. Such as figure 1 As shown in , it is an example of two expressions for displaying character codes. This figure shows the equivalence relationship between characters and octal sequences. In the first line of the figure, the display character code in the operand of operator TJ is expressed in the form of character C; in the second line, the display in the operand of operator TJ Character codes are expressed in the form of the octal sequence \ddd. Both describe the content as "Researchon". Such as figure 2 Shown is a transfer sequence diagram that partially displays character codes. join figure 2 , the "\" in the operand of the operator TJ is an escape character, adding a backslash before the character has a strict meaning of interpretation, the first column in the table is the character code sequence, and the second...

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PUM

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Abstract

The invention relates to a method for embedding and extracting hidden information based on English PDF documents. The embedding method includes: reading in the data stream of the PDF document; reading in the hidden information to be embedded and converting it into a binary string; analyzing the logical structure of the PDF document to find out all page content stream objects; decompressing the content of the page content stream object Stream, by modifying the representation of the displayed character code, embed a certain bit of information header in the page content stream to indicate the length of the hidden information, and then embed the hidden information that has been converted into a binary string after the information header; recompress the content stream and write Input the file body; update the cross-reference table and file trailer according to the length change of the content stream after recompression; output the PDF document with embedded hidden information. The invention can embed and extract hidden information in English PDF documents, has good visual concealment and is robust to general editing behavior of documents.

Description

technical field [0001] The invention relates to the field of multimedia signal processing, more specifically, to a method for embedding and extracting hidden information based on English PDF documents. Background technique [0002] In recent years, with the rapid development of network technology, people have begun to transmit and obtain information more and more through the Internet. At the same time, new office models such as e-commerce and e-government are being widely used, and more and more administrative and commercial documents, such as authorization letters, registration forms, contracts, invoices, etc., have begun to be circulated and transmitted in the form of electronic documents. However, in the open environment of the Internet, malicious acts such as copying and tampering always threaten the copyright ownership of electronic documents, and a large number of copyright theft, illegal transmission, information forgery and other problems emerge in endlessly. Based ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F21/64
CPCG06F21/10G06F21/1062G06F21/1066
Inventor 刘红梅林少柳黄继武
Owner SUN YAT SEN UNIV
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