Paper Info
Title
The hiding virtues of ambiguity: quantifiably resilient watermarking of natural language text through synonym substitutions
Abstract
Information-hiding in natural language text has mainly consisted of carrying out approximately meaning-preserving modifications on the given cover text until it encodes the intended mark. A major technique for doing so has been synonym-substitution. In these previous schemes, synonym substitutions were done until the text "confessed", i.e., carried the intended mark message. We propose here a better way to use synonym substitution, one that is no longer entirely guided by the mark-insertion process: It is also guided by a resilience requirement, subject to a maximum allowed distortion constraint. Previous schemes for information hiding in natural language text did not use numeric quantification of the distortions introduced by transformations, they mainly used heuristic measures of quality based on conformity to a language model (and not in reference to the original cover text). When there are many alternatives to carry out a substitution on a word, we prioritize these alternatives according to a quantitative resilience criterion and use them in that order. In a nutshell, we favor the more ambiguous alternatives. In fact not only do we attempt to achieve the maximum ambiguity, but we want to simultaneously be as close as possible to the above-mentioned distortion limit, as that prevents the adversary from doing further transformations without exceeding the damage threshold; that is, we continue to modify the document even after the text has "confessed" to the mark, for the dual purpose of maximizing ambiguity while deliberately getting as close as possible to the distortion limit. The quantification we use makes possible an application of the existing information-theoretic framework, to the natural language domain, which has unique challenges not present in the image or audio domains. The resilience stems from both (i) the fact that the adversary does not know where the changes were made, and (ii) the fact that automated disambiguation is a major difficulty faced by any natural language processing system (what is bad news for the natural language processing area, is good news for our scheme's resilience). In addition to the above mentioned design and analysis, another contribution of this paper is the description of the implementation of the scheme and of the experimental data obtained.
Year
DOI
Venue
2006
10.1145/1161366.1161397
MM&Sec
Keywords
Field
DocType
synonym substitution,original cover text,language model,natural language domain,previous scheme,hiding virtue,quantifiably resilient watermarking,quantitative resilience criterion,cover text,natural language text,natural language processing system,natural language processing area,natural language,information hiding
Digital watermarking,Heuristic,Computer science,Information hiding,Natural language,Homograph,Natural language processing,Artificial intelligence,Language identification,Ambiguity,Language model
Conference
ISBN
Citations 
PageRank 
1-59593-493-6
36
1.80
References 
Authors
18
3
Name
Order
Citations
PageRank
Umut Topkara133624.04
Mercan Topkara226719.51
Mikhail J. Atallah33828340.54