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This work improves synonym-substitution encoding through two key mechanisms: it uses the Google n-gram corpus to test whether a candidate synonym is applicable in context, and it resolves ambiguity from words with multiple senses by assigning bits via a novel vertex coding method. Words become graph vertices, synonyms connect by edges, and a vertex coding algorithm yields a unique bit sequence per word while preserving reasonable embedding capacity and avoiding excessive synonym pruning.",{"@graph":63,"@context":118},[64,80,101],{"@type":65,"itemListElement":66},"BreadcrumbList",[67,71,74,77],{"item":68,"name":69,"@type":70,"position":9},"https://docshare.wps.com","Home","ListItem",{"item":72,"name":10,"@type":70,"position":73},"https://docshare.wps.com/template/",2,{"item":75,"name":51,"@type":70,"position":76},"https://docshare.wps.com/template/general/",3,{"item":78,"name":59,"@type":70,"position":79},"https://docshare.wps.com/template/practical-linguistic-steganography-using-contextual-synonym-substitution-and-a-novel-vertex-coding-method/256371/",4,{"url":78,"name":59,"@type":81,"image":82,"author":87,"headline":59,"publisher":90,"fileFormat":93,"inLanguage":57,"description":61,"dateModified":94,"datePublished":95,"encodingFormat":93,"isAccessibleForFree":96,"interactionStatistic":97},"DigitalDocument",{"url":83,"@type":84,"width":85,"height":86},"https://docshare.wps.com/thumbnails/practical-linguistic-steganography-using-contextual-synonym-substitution-and-a-novel-vertex-coding-method/256371.png","ImageObject",442,249,{"name":88,"@type":89},"Mimi","Person",{"url":68,"name":91,"@type":92},"DocShare","Organization","application/pdf","2026-09-20","2026-09-13",true,{"@type":98,"interactionType":99,"userInteractionCount":9},"InteractionCounter",{"@type":100},"ViewAction",{"@type":102,"mainEntity":103},"FAQPage",[104,110,114],{"name":105,"@type":106,"acceptedAnswer":107},"How does the method embed hidden information into natural language text?","Question",{"text":108,"@type":109},"It hides bits by replacing selected cover words with context-appropriate synonyms, where the specific word choice corresponds to encoded bits.","Answer",{"name":111,"@type":106,"acceptedAnswer":112},"How is synonym applicability in context ensured?",{"text":113,"@type":109},"The system checks whether a synonym fits the surrounding context using the Google n-gram corpus.",{"name":115,"@type":106,"acceptedAnswer":116},"How does the vertex coding method handle ambiguity from multiple word senses?",{"text":117,"@type":109},"It models words as vertices in a graph and assigns codes to substitutes using a vertex coding algorithm, so each word corresponds to a unique bit sequence.","https://schema.org",{"og:url":78,"og:type":120,"og:title":59,"og:site_name":91,"og:description":61},"article",{"robots":122,"canonical":78},"index,follow",{"doc_id":124,"site_id":56},256371,1789302752,{"code":4,"msg":5,"data":127},{"doc_id":124,"user_id":128,"nickname":88,"user_avatar":129,"doc_module":9,"category_id":50,"category_name":51,"doc_title":59,"doc_description":61,"doc_content":130,"file_id":131,"file_url":132,"file_type":133,"file_size":134,"view_count":9,"is_deleted":4,"is_public":9,"is_downloadable":9,"audit_status":9,"page_count":135,"language":136,"language_code":57,"site_id":56,"html_lang":57,"table_of_contents":137,"faqs":138,"seo_title":139,"seo_description":61,"update_tm":125,"read_time":30},2336477974920,"https://ap-avatar.wpscdn.com/davatar_155a257f0dc6eb9ab79c44ca47cae57d","Practical Linguistic Steganography using Contextual Synonym Substitution and a Novel Vertex Coding Method  \nChing-Yun Chang􀀃 University of Cambridge  \nStephen Clark􀀃􀀃 University of Cambridge  \nLinguistic steganography is concerned with hiding information in natural language text. One of the major transformations used in linguistic steganography is synonym substitution. However, few existing studies have studied the practical application of this approach. In this article we propose two improvements to the use of synonym substitution for encoding hidden bits of information. First, we use the Google n-gram corpus for checking the applicability of a synonym in context, and we evaluate this method using data from the SemEval lexical substitution task and human annotated data. Second, we address the problem that arises from words with more than one sense, which creates a potential ambiguity in terms of which bits are represented by a particular word. We develop a novel method in which words are the vertices in a graph, synonyms are linked by edges, and the bits assigned to a word are determined by a vertex coding algorithm. This method ensures that each word represents a unique sequence of bits, without cutting out large numbers of synonyms, and thus maintains a reasonable embedding capacity.  \n1. Introduction  \nIn order to transmit information through an open channel without detection by anyone other than the receiver, a covert channel can be used. In information theory, a covert channel is a parasitic communications channel that is hidden within the medium of a legitimate communication channel (Lampson 1973) . For example, steganography is a form of covert channel in which certain properties of the cover medium are manipulated in an unexpected, unconventional, or unforeseen way so that, with steganographic transmission, the encrypted messages can be camouflaged in a seemly innocent medium and sent to the receiver with less chance of being suspected and attacked. Ideally, because the changes to the medium are so subtle, anyone not specifically looking fora hidden message is unlikely to notice the changes (Fridrich 2009) .  \n􀀃 15 JJ Thomson Avenue, Cambridge CB3 0FD, [UK. E-mail: Ching-Yun.Chang@cl.cam.ac.uk](UK. E-mail: Ching-Yun.Chang@cl.cam.ac.uk).  \n􀀃􀀃 15 JJ Thomson Avenue, Cambridge CB3 0FD, UK. [E-mail: Stephen.Clark@cl.cam.ac.uk](E-mail: Stephen.Clark@cl.cam.ac.uk).  \nSubmission received: 18 January 2013; revised version received: 3 June 2013; accepted for publication:  \n1 August 2013 .  \ndoi:10 . 1162/COLI a 00176  \n© 2014 Association for Computational Linguistics  \nComputational Linguistics Volume 40, Number 2  \nIn this article, we aim at concealing secret information in natural language text by manipulating cover words. The proposed steganography system replaces selected cover words with their synonyms, which is the mechanism used to embed information. In order to ensure the lexical substitutions in the cover text are imperceptible, the system uses the Google n-gram corpus (Brants and Franz 2006) for checking the applicability of a synonym in context. In addition, the system assigns codes to acceptable substitutes using a novel vertex coding method in which words are represented as vertices in a graph, synonyms are linked by edges, and the bits assigned to a vertex represent the code of a particular word. Our lexical substitution-based steganography system was previously published in Chang and Clark (2010b), in which the system was evaluated automatically by using data from the English lexical substitution task for SemEval- 2007.1 In this article, we extend the previous work by more closely addressing the practical application of the proposed system. We present results from a new human evaluation of the system's output and a simple computational steganalysis of wordfrequency statistics which is a more direct evaluation for linguistic steganography. We also give an extended literature review which will serve as a useful intro","cbCaidnxv4vWfs4A","https://ap.wps.com/l/cbCaidnxv4vWfs4A","pdf",1300607,46,"English","# Introduction\n## Steganography","[{\"question\":\"How does the method embed hidden information into natural language text?\",\"answer\":\"It hides bits by replacing selected cover words with context-appropriate synonyms, where the specific word choice corresponds to encoded bits.\"},{\"question\":\"How is synonym applicability in context ensured?\",\"answer\":\"The system checks whether a synonym fits the surrounding context using the Google n-gram corpus.\"},{\"question\":\"How does the vertex coding method handle ambiguity from multiple word senses?\",\"answer\":\"It models words as vertices in a graph and assigns codes to substitutes using a vertex coding algorithm, so each word corresponds to a unique bit sequence.\"}]","Practical Linguistic Steganography using Contextual Synonym Substitution and a Novel Vertex Coding Method | PDF"]