Advanced Engneerng Forum Onlne: 2012-09-26 ISSN: 2234-991X, Vols. 6-7, pp 361-366 do:10.4028/www.scentfc.net/aef.6-7.361 2012 Trans Tech Publcatons, Swtzerland A Robust Webpage Informaton Hdng Method Based on the Slash of Tag Yujun Yang 1,2,a, Yme Yang 1,b 1 Department of Computer Scence and Technology, Huahua Unversty, Huahua, 418008, Chna 2 School of Computer Scence and Engneerng, Unversty of Electronc Scence and Technology, Chengdu, 610054, Chna a mlsoft163@163.com, b yym1630@163.com Keywords: Slash; Informaton Hdng; Tag Attrbute; Webpage. Abstract. Nowadays,the nformaton hdng technology s a hot spot n the feld of nformaton securty, and s appled n many felds,such as dgtal multmeda copyrght protecton and secret communcaton. Accordng to the analyss of the characterstcs of browser n parsng HTML of the webpage and the lttle capacty avalable for nformaton hded n webpage, a new robust webpage nformaton hdng method wth the slash of tag attrbutes has been proposed n ths paper, whch overcomes the shortcomng of the ablty of mperceptblty and the ablty of contradct wth the machne fltraton of tradtonal webpage nformaton hdng algorthms and has greater embedded capacty than some other algorthm based on tag attrbutes. Ths method has good performances n nvsblty and hgher appled value as proved by the experments. Introducton Informaton hdng[1] s to hde some secret nformaton n nnocuous-lookng cover objects, such as audos, mages, vdeos, texts, etc.. In recent years, Informaton hdng has generated sgnfcant research and commercal nterest. The prmary factors contrbutng to ths surge are wdespread use of the Internet wth mproved bandwdth and speed, regonal copyrght loopholes n terms of legslaton; and seamless dstrbuton of multmeda content due to peer-to-peer fle-sharng applcatons. HTML s a hypertext markup language for wrtng hypertext fles, namely webpages, whch are used to convey nformaton through the Internet. Wth the development of the Internet as a man communcatve means, webpages have enjoyed an extensve applcaton n the Internet. Meanwhle, a wde varety of steganographc methods[2-4] for webpages have emerged. Accordng to the analyss of the characterstcs of browser n parsng HTML of the webpage, the source codes of a webpage are a plan text that contans small markup tags, by whch the web browser s nstructed how to dsplay the page. Informaton hdng based on webpage uses a webpage as a cover, and then embeds some secret nformaton nto the source codes of the webpage, whle the dsplayng effect wll reman unchanged. Through analyzng the crteron of HTML and References [2-5], we have defned three man nformaton hdng methods: 1) Based on the nvsble characters embeddng; 2) Based on the changng of letter upper and lower cases n tags; 3) Based on the changng the order of attrbute tags par. The frst two methods are nformaton hdng methods based on document format. The method of embeddng nvsble characters s to embed extra nvsble characters between tags, or after every row, or after the whole document, to encode secret nformaton. The second method s based on the fact that letters n tags are always case-nsenstve, therefore the cases of tag letters can be modfed wthout changng the vsble document or the fle sze. So, defne the uppercase letter as the bt 0 and the lowercase letter as 1, secret nformaton can be embedded nto a webpage by changng of the letters upper and lower cases n tags. A new robust webpage nformaton hdng method wth the slash of tag attrbutes has been proposed n ths paper, whch overcomes the shortcomng of the ablty of mperceptblty and the ablty of contradct wth the machne fltraton of tradtonal webpage nformaton hdng Ths s an open access artcle under the CC-BY 4.0 lcense (https://creatvecommons.org/lcenses/by/4.0/)
362 Informaton Technology for Manufacturng Systems III algorthms and mproves the embedded capacty of the other algorthm based on tag attrbutes. Accordng to the embedded rule, frstly the sequenced tags entty set s acqured from the webpage. Then the message s encrypted by a two-value chaotc sequence generated by Logstc map system. The value format of a certan attrbute n tags s selected and a modfcaton s made to them based on the encrypted message, whch s whether t has sngle quotaton mark. The analyss shows that the method has good mperceptblty and perfect securty than the tradtonal method. And the embedded capacty of the method gets better ncrease than the method based on the attrbutes of tags. So the method could be used to protect the content of a webpage and covert communcaton. The Method The Proposed Scheme. In ths secton, we wll present the proposed nformaton hdng scheme based on the slash of webpage tags. The process dagram of the scheme, whch s composed of the nformaton embeddng process and the nformaton extracton process, s shown n Fg. 1. The embeddng process s used to hde the secret data n the cover webpage, whle the extracton process s used to extract the secret data from the hdden webpage. Server Sde Cover Webpage Secret Data Preprocess Hdden Webpage Embeddng Process Embeddng Internet Extracton Process Secret Data Inverse process Hdden Webpage Clent Sde Extractng Fg 1. The Process Dagram of the Proposed Scheme The Related Theoretcs. Defnton 1. Let T=<a 1, a 2,, a n > be a tag wth n attrbutes n HTML, where T s the name of the tag and a (1 n), whose general form s attrbute name=attrbute value (short for name=value), s the -th attrbute of the tag. And let Ts be a sngle tag wthout end tags n HTML, meanwhle let Td be a double tag wth startng and endng Tags. The startng component of any tag s the tag name and ts attrbutes, f any. The correspondng endng tag s the tag name alone, preceded by a slash (/). Endng tags have no attrbutes. Defnton 2. Let W be number of webpage tags, where W s a webpage. And let T be a number of attrbutes of the -th webpage tag, where T s the -th tag n the webpage. Defnton 3. Let O be a object that s composed of a attrbute and a value of the attrbute n a tag, where O s the -th object n the tag. For example, the sze=21px s O 1 and the color=green s O 2 n the tag <font sze=21px color=green>. Defnton 4. Let T and T be a par of equal tag object, where T s a tag object wthout slash marks, T s a tag object wth a slash marks. For example, the T s <font sze=5 >, the T s <font sze=5 />. That s T T. By studyng thoroughly, we found that the vew results do not occur any change between the orgnal webpages and the modfed webpages usng the equal attrbute object n the browser. Property 1. Equal attrbute object has the dentcal functon.
Advanced Engneerng Forum Vols. 6-7 363 Rule 1. Embedded decson rule. If a tag object T s a Ts tag or the startng component of any Td tag such that the <br> tag s a Ts tag and the <font sze=4> tag s the startng component of Td tag <font sze=4> </font>, the T meets the nserton requrement; Otherwse, the T does not meet the nserton requrement. Rule 2. Extracton decson rule. If a tag object T wth the slash marks s a Ts tag or the startng component wth the slash marks of any Td tag such that the <br /> tag s a Ts tag and the <font sze=4 /> tag s the startng component of Td tag <font sze=4> </font>,, the T meets the extracton requrement; Otherwse, the T does not meet the extracton requrement. Rule 3. Embedded rule. W Step 1: Let = 1, where 1 T k k 1 Step 2: If the T meets the nserton requrement of Rule 1, then go to Step 4. Step 3: Let = + 1. If the W, then go to Step 2. Otherwse, go to Step 5. ' Step 4: The T s modfed to the T, and let = + 1.If the W, then go to Step 2. Step 5: Fnshed. Rule 4. Extracton rule. Step 1: Let = 1, where 1 W T k k 1 Step 2: If the T meets the extracton requrement of Rule 2, then go to Step 4. Step 3: Let = + 1. If the W, then go to Step 2. Otherwse, go to Step 5. Step 4: We extract a secret nformaton bt, and let = + 1.If the W, then go to Step 2. Step 5: Fnshed. The Hdng Process. Let W={ T 1, T 2,, T n } be a cover webpage, where T s a tag n the webpage. And let M={ m 1, m 2,, m n } be the secret data bts to be embedded n the cover webpage. In order to ncrease the secrecy of the proposed scheme, we generate a chaotc sequence L={ l 1, l 2,, l n }, accompaned by a secret key to manpulate t, by the Logstc map system. Then the secret data bts s calculated by usng the Eq.1. S=M L={ s 1, s 2,, s n }={ m 1 l 1, m 2 l 2,, m n l n } (1) We use the S={ s 1, s 2,, s n } to determne whether the tag can be used to hde nformaton or not accordng to the Rule 3. The hdng process can be descrbed as follows: Step 1: Calculate the M form the secret data and generate the L by the Logstc map system and the secret key K, then Calculate the S from the M and the L. Step 2: Accordng to the Rule 1, check every tag object T of the webpage to determne whether the tag object T can be used to hde nformaton or not. In our new method, f there s a equal tag object T n the tag T, then the tag T s called embeddable tag. ' Step 3: For the embeddable tag object, f the secret data bt of the S s 1, then replace the T wth the T for nformaton hdng accordng to the value of the secret date bt. Otherwse, f the secret data bt s 0, the scheme retans the orgnal tag object. The payload capacty of the proposed scheme s gven by Eq.2 W Capa = T k (2) The Extracton Process. In ths subsecton, we shall descrbe the extracton process. The followng extracton procedure s used to extract the embedded secret data. The extracton process can be descrbed as follows: Step 1: Accordng to the Rule 2, check every tag object T of the webpage to determne whether the tag object T has been used to hde nformaton or not. In our new method, f there exsts the tag object T, then the hdden secret data bt s s 1; otherwse, the hdden secret bt s s 0. ' k 1
364 Informaton Technology for Manufacturng Systems III Step 2: Snce the recever owns the secret key used to generate the chaotc sequence L by the Logstc map system, the orgnal secret data can be calculated by usng the Eq.3. M=S L={m 1, m 2,, m n }={ s 1 l 1, s 2 l 2,, s n l n } (3) The Experments The experments were carred out to evaluate the performance of the proposed nformaton hdng scheme based on the slashs of tag n the webpage. The proposed scheme was tested on Wn 7 personal computer wth a Pentum IV 2.66GHz and 4G RAM. And sx homepages of pop webste were used as the cover webpage. The Expermental Results. We have mplemented the proposed nformaton hdng method n the Vsual C++ 6.0 envronment. The experment result shows that the vew results dd not occur any change between the orgnal webpages and the modfed webpages usng the equvalent tag object n the browser. Fg. 2 and Fg.3 show the embedded secret data before and after webpage renderngs. Fg. 4 and Fg. 5 show the source screenshots of the embedded secret data before and after webpage. Fg. 2. The WebPage Renderng Before Embedded Secret Data Fg. 3. The WebPage Renderng After Embedded Secret Data Fg. 4. The Source Screenshot Before Embedded Secret Data Fg. 5. The Source Screenshot After Embedded Secret Data 01010111 At the same tme, the homepage on the popular webste has been tested for the maxmum hdden amount of webpage. Table 1 shows the largest embedded capacty, whch s called LEC for short, of the homepages on some popular webstes whch were vsted on June 5, 2012. And the expermental results show that the method has good mperceptblty and perfect securty than the method whch was proposed n [6].
Advanced Engneerng Forum Vols. 6-7 365 Table 1 The LEC of Homepages on Some Popular Webstes Homepage of Webste LEC(b) of our method Method LEC(b) of method n [6] LEC(b) of method n [7] www.163.com 2701 376 3984 www.yahoo.com 908 215 1332 www.mcrosoft.com 821 127 3242 www.sohu.com.cn 1826 624 4606 www.ebay.com 111 38 147 www.sna.com.cn 2753 1892 8274 The Performance Evaluaton. Table 2 shows the performance parameters of our method and other sx algorthms whch are the nvsble character, the changng uppercase and lowercase of tag, the order of attrbutes par, the equal tag dsplacement and the repeat attrbute of the tag algorthm. The nvsble character method whch do not effect the normal show hde the secret nformaton by addng spaces and tabs on the end of the lne, but those who do not see characters at a glance when the source code of the hdden nformaton page were selected smply. The changng uppercase and lowercase of tag method whch do not effect the normal show too hde the secret nformaton by usng the tags characterstcs of case-nsenstve n the HTML norms, however the artfcal alter of the tags s very easy found by observng the source code of the hdden secret nformaton webpages, and then the hdden message was exposed. The changng order of attrbutes par method whch has strong ant-testng capablty hde the secret data by changng the order of attrbutes par n the webpage, but the extractng secret data needs the orgnal database whch generates addtonal transmsson at the tme of transportng. The equal tag dsplacement method n [6] whch has strong ant-testng capablty do not change the orgnal fle sze after hdng secret nformaton. Even vewng the page s source code can not determne whether hdden secret nformaton n the webpage. But we can not hde any nformaton n the page whle all tags of page have one attrbute at most. The equal tag attrbutes method n [7] do not almost change the orgnal fle sze after hdng secret nformaton,and the equal tag attrbutes s not easy found by observng the source code of the hdden secret nformaton webpages, but t has not strong ant-testng capablty and the hdden secret nformaton was not extracted correctly, f someone changed the order of the equal tag attrbutes. The repeat attrbute of tag method n [8] changes the fle sze on bgger degree and the repeat attrbutes of the tag s very easy found by observng the source code of the hdden secret nformaton webpages, and then the hdden secret nformaton was exposed. Our method does not change the dsplay of the content and appearance of webpages after hdng secret nformaton. The hdden secret nformaton was not found by vewng the source code of the webpage. And then anyone can't change the order of the equal tag or else the webpage was not dsplay properly. Accordng to the above experment result, our method has strong ant-testng capablty, strong securty capablty, strong robustness capablty, good mperceptblty and larger embedded capacty than other methods, such as the equal tag dsplacement method n [6] and the equal tag attrbutes method n [7]. Method Table 2 Performance Parameters of Fve Algorthms Imperceptblty Robustness Parameter Change Fle Sze Aganst of Detecton Securty Invsble Character Good Weak Yes Weak Weak Changng Case of Tag Good Weak No Weak Weak Order of Attrbutes Par Good Strong No Strong Strong Equal Tag Dsplacement n [6] Good Strong No Strong Strong Equal tag Attrbute Dsplacement n [7] Good Strong Yes Strong Strong Repeat Attrbute of Tag n [8] Good Strong Yes Strong Strong Our Method Good Strong Yes Strong Stronger
366 Informaton Technology for Manufacturng Systems III Conclusons and future works Informaton hdng technology s a hot spot n nformaton securty, and s appled n the felds of dgtal multmeda copyrght protecton and secret communcaton. Accordng to the analyss of the characterstcs of browser n parsng HTML of the webpage and the lttle capacty avalable for nformaton hded n webpage, a new effcent webpage nformaton hdng method wth equal tag has been proposed n ths paper, whch overcomes the shortcomng of the ablty of mperceptblty and the ablty of contradct wth the machne fltraton of tradtonal webpage nformaton hdng algorthms and mproves the embedded capacty of the other algorthm based on tag attrbutes. Ths method has good performances n nvsblty and hgher appled value as proved by the experments. So we conclude that the proposed method s practcal n many real applcatons. The next work s to study how to mproves the embedded capacty and securty capablty of the method by usng the relatve lnks of the webpages and mult-webpage embedment technology or other ones. Acknowledgment Ths work s supported by the Constructng Program of the Key Dscplne n Huahua Unversty, by Scentfc Research Fund of Hunan Provncal Educaton and by Scentfc Research Fund of Huahua Unversty(HHUY2011-17, 201125). References [1] F. A. P. Pettcolas, R. J. Anderson, M. G. Kuhn, Informaton hdng-a survey, Proceedngs of the IEEE, vol.3, 1999, pp. 1062 1078. [2] C. John, Hdng Bnary Data n HTML Documents, http://www.codeproject.com/csharp/ steganodotnet13.asp, 2011-12-24. [3] Q. J. Zhao, H. T. Lu, A PCA-based Watermarkng Scheme for Tamper-proof of Web pages, Pattern Recognton, Elsever Scence, Oxford, ROYAUMEUNI, 2005, vol.38, no.8,pp.1321-1323. [4] Q. J. Zhao, H. T. Lu, X. H. Jang, Web page Watermarkng for Tamper-proof, Journal of Shangha Jaotong Unversty(Scence), Chna, 2005, vol. 3, no.e-10,pp.280-284. [5] L. Hu, X. G. You, Analyss of HTML nformaton hdng technology, In Proc of CIHW2001, X an: Xdan Unversty Press, 2001, pp. 62-67. [6] X. M. Sun, H. J. Huang, B. W. Wang, G. Sun, J. W. Huang, An Algorthm of Webpage Informaton Hdng Based on Equal Tag, Journal of Computer Research and Development, 2007,vol.44,no.5,pp.756-760. [7] Y. J. Yang, Y. M. Yang, An Effcent Webpage Informaton Hdng Method Based on Tag Attrbutes, Fuzzy Systems and Knowledge Dscovery, 2010 Seventh Internatonal Conference on,2010,vol.3,no.7,pp.1181-1184. [8] J. G. L, X.H. Ma, X. F. Shen, A Novel Scheme of Multple Webpages Informaton Hdng Based on Repeatng Tag Attrbutes, Computer Applcatons and Software, 2009, vol.26, no.8, pp. 62-64.