基于貝葉斯算法分類的反垃圾郵件系統的改進碩士學位論文(已修改)

　

【正文】 長春工業大學碩士學位論文1學位論文題目：基于貝葉斯算法分類的反垃圾郵件系統的改進 摘 　要電子郵件成為一種快捷、經濟的現代通信技術手段，極大地方便了人們的通信與交流。然而，垃圾郵件的產生，影響了正常的電子郵件通信，占用了傳輸帶寬，對系統安全造成了嚴重的威脅。因此，研究反垃圾郵件問題已經成為全球性的具有重大現實意義的課題。目前，應對垃圾郵件的主要方法和手段是通過反垃圾郵件立法和使用郵件過濾技術進行處理，現已相繼出現了多種郵件過濾技術。常用的包括黑/白名單技術、基于內容的分析方法以及基于規則的方法等?；趦热莘治龅募夹g正逐步進入郵件過濾技術當中，并成為當前研究熱點，其中，基于內容分析的郵件過濾方法中的典型方法是基于貝葉斯算法的垃圾郵件過濾模型。本論文對中文垃圾郵件的特點進行了比較系統的分析和研究，結合貝葉斯（Bayes）理論，構造基于貝葉斯分類的垃圾郵件過濾模型，在特征提取方面，采用互信息值的方法，在分類方法上，引入了適合本文的分類方法，并采用了一種更加適合于貝葉斯計算的表示方法；本文作者采用中國教育科研網（CERNET）收集并維護的大量中文垃圾郵件和正常郵件樣本的標準數據集，對本文研究的方法進行了大量測試，準確率和誤判率分別達到了 %和 %。結果表明基于貝葉斯算法的垃圾郵件過濾系統對攔截垃圾郵件有很好的作用。關鍵詞：電子郵件，垃圾郵件，郵件過濾，貝葉斯理論AbstractThe has bee a quick and economical means of modern munication technology, which enormously facilitates people39。s munication and exchanges. However, the emergence of spam has affected the normal correspondence, and taken the transmission band width, even posed the serious threat to the system safety. Therefore, the study of antispam has bee a global problem of great practical significance of the topic.At present, the main ways and means of the response to spam are the antispam legislation and the use of mail filtering technology. But now a variety of mail filtering technologies have appeared in succession, which are usually used including black / white list 2technologies, contentbased analysis methods, and rulebased methods. Contentbased analysis techniques are gradually entering the mail filtering technology which has bee hot spots of current research. The typical method of contentbased analysis mail filtering methods is based on Bayesian algorithm for spam filtering model.In this paper, the Chinese characteristics of spam has been studied and analyzed systematically. Combining with Bayesian (Bayes) theory, this paper constructs the spam filtering model which is based on Bayesian classification. In feature extraction, mutual information values are used. In the classification method, a classification method is introduced which is suitable in this article, and a more suitable expression in the Bayesian calculation method is adopted。 the standard sample data sets of a large number of Chinese spam and regular mail are collected and maintained by the Chinese Education and Research Net (CERNET). The author conducted a lot of testing towards the methods which are studied by this paper. The accuracy and misjudgment rate reached % and % respectively. The results show that the spam filtering system based on algorithm Bayesian plays a very good role to block spam.Key Words: , spam, mail filtering, Bayesian theory3學位論文原創性聲明本人鄭重聲明：所呈交的論文是本人在導師的指導下獨立進行研究所取得的研究成果。除了文中特別加以標注引用的內容外，本論文不包含任何其他個人或集體已經發表或撰寫的成果作品。對本文的研究做出重要貢獻的個人和集體，均已在文中以明確方式標明。本人完全意識到本聲明的法律后果由本人承擔。作者簽名： 日期： 年 月 日學位論文版權使用授權書本學位論文作者完全了解學校有關保留、使用學位論文的規定，同意學校保留并向國家有關部門或機構送交論文的復印件和電子版，允許論文被查閱和借閱。本人授權　　 　 　大學可以將本學位論文的全部或部分內容編入有關數據庫進行檢索，可以采用影印、縮印或掃描等復制手段保存和匯編本學位論文。涉密論文按學校規定處理。作者簽名： 日期： 年 月 日導師簽名： 日期： 年 月 日4目 錄第一章 緒論 .............................................................................................................................3 引言 ..............................................................................................................................................................3 垃圾郵件的定義及其危害 ..........................................................................................................................4 垃圾郵件定義 ......................................................................................................................................4 垃圾郵件危害 [5]...................................................................................................................................4 國內外反垃圾郵件現狀 ..............................................................................................................................6 研究目標與內容 ..........................................................................................................................................7第二章 垃圾郵件技術 .............................................................................................................7 電子郵件工作原理簡介 ..............................................................................................................................7 電子郵件的概述 ..................................................................................................................................7 電子郵件的格式 ..................................................................................................................................8 郵件傳送過程 ......................................................................................................................................9 相關協議 ............................................................................................................................................10 非技術手段反垃圾郵件 ............................................................................................................................15 常用反垃圾郵件技術 ................................................................................................................................16 客戶端垃圾郵件過濾技術 .................................................................................................................16 服務器端垃圾郵件過濾技術 ............................................................................................................17第三章垃圾郵件分類向量與特征向量 .................................................................................19 垃圾郵件分類向量概述 ............................................................................................................................19 垃圾郵件分類向量與特征向量的定義 ....................................................................................................20 分類方法 .........................................................................................................................