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SUMMARY:Practical Linguistic Steganography using Synonym Substitution - Ch
 ing-Yun (Frannie) Chang &amp\; Stephen Clark\, University of Cambridge
DTSTART:20110517T151500Z
DTEND:20110517T161500Z
UID:TALK29875@talks.cam.ac.uk
CONTACT:Wei Ming Khoo
DESCRIPTION:Linguistic Steganography is concerned with hiding information 
 in a natural language text\, for the purposes of sending secret messages. 
 A related area is natural language watermarking\, in which information is 
 added to a text in order to identify it\, for example for the purposes of 
 copyright. Linguistic Steganography algorithms hide information by manipul
 ating properties of the text\, for example by replacing some words with th
 eir synonyms. Unlike image-based steganography\, linguistic steganography 
 is in its infancy with little existing work. In this talk we will motivate
  the problem\, in particular as an interesting application for Natural Lan
 guage Processing (NLP) and especially natural language generation. Linguis
 tic steganography is a difficult NLP problem because any change to the cov
 er text must retain the meaning and style of the original\, in order to pr
 event detection by an adversary.\n\nOur method embeds information in the c
 over text by replacing words in the text with appropriate substitutes. We 
 use a large database of word sequences collected from the Web (the Google 
 n-gram data) to determine if a substitution is acceptable\, obtaining prom
 ising results from an evaluation in which human judges are asked to rate t
 he acceptability of modified sentences.
LOCATION:Lecture Theatre 2\, Computer Laboratory\, William Gates Building
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