資訊安全
資訊系統安全屬性
對稱加密與非對稱加密
資訊摘要 數字簽名 數字信封與PGP
[實體]設計郵件加密系統 網路各層次的安全保障
網路威脅與攻擊 防火墻技術
資訊系統安全屬性
安全屬性
屬性 描述 保密性 最小授權原則 ,防暴露,資訊加密,物理保密完整性 安全協議,校驗碼 ,密碼校驗,數字簽名,公證 可用性 綜合保障(IP過濾,業務流程控制,路由選擇控制,審計跟蹤) 不可抵賴性 數字簽名
對稱加密與非對稱加密
對稱加密 :加密和解密使用的密鑰完全一樣.非對稱加密 :加密和解密使用的密鑰不一樣.公鑰加密,私鑰解密或者私鑰加密,公鑰解密.
對稱加密
缺陷:加密強度不高,密鑰分發困難.
非對稱加密
缺陷:加密速度慢,不適合加密大資料量的資料給誰發資訊,用誰的公鑰加密. 日常使用的PDF,DOC,RAR等加密,使用的是對稱加密技術 (加密使用的密鑰和解密輸入的密鑰一樣 )
資訊摘要
單向散列函式(單向Hash函式),固定長度的散列值. :資訊摘要演算法不能用來加密 .
數字簽名
一種防抵賴的技術,由于發送的資料使用了發送者的私鑰進行簽名,在驗證時只能使用發送者的公鑰驗證,所以此技術非加密 技術.
Created with Rapha?l 2.3.0
開始
資訊正文發送至Receiver
對資訊摘要使用自己的私鑰加密
加密后的資訊摘要發送至Receiver
結束
接收流程
Created with Rapha?l 2.3.0
開始
接收正文,產生摘要a
接收簽名資訊,使用發送方公鑰解密得到摘要b
摘要a與摘要b一致?
驗簽成功
結束
驗簽失敗
yes
no
數字信封與PGP
數字信封
對稱加密適合加密大資料量,非對稱加密適合加密小資料量
PGP
一種加密協議,采用了雜合演算法.適應于郵件或檔案加密.
[實體]設計郵件加密系統
決議 :加密傳輸 : 加解密技術大附件 : 對稱加密不可抵賴 : 數字簽名第三方不能篡改 : 資訊摘要
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隨機密鑰K
Sender私鑰S
Receiver公鑰R
Sender
郵件正文
隨機密鑰K
郵件摘要
用K加密后的正文
用S加密后的簽名
用R加密后的K
Receiver
網路各層次的安全保障
物理層
隔離或屏蔽 ,常見于高敏感度的實驗室或者軍工專案
資料鏈路層
從本層及向上層次,開始使用協議進行控制.鏈路加密,PPTP,L2TP
網路層
防火墻,IPSec.
傳輸層
TLS,SET,SSL
應用層
PGP,Https(Http+SSL)
網路威脅與攻擊
威脅 描述 重放攻擊 利用了ARP協議的漏洞,截獲某次合法通信資料拷貝,出于非法目的而重新發送 拒絕服務(DOS) 對資訊或其它資源的合法訪問被無條件阻止,影響了服務的可用性 竊聽 用各種可能的合法或非法的手段竊取系統中的資訊資源和敏感資訊 業務流分析 通過對系統進行長期監聽 ,利用統計分析方法對通信引數進行研究 ,從而發現有價值的資訊或規律 資訊泄露 資訊被泄露或透漏給某個非授權的物體 破壞資訊完整性 資料被非授權地進行增刪,修改或破壞而受到損失 非授權訪問 某一資源被某個非授權的人或以非授權的方式使用 假冒 通過欺騙通信系統(或用戶)達到非法用戶冒充合法用戶,黑客大多采用假冒進行攻擊 旁路控制 利用系統安全缺陷或者安全脆弱處,獲得非授權的權利 授權侵犯 “內部攻擊” 特洛伊木馬 軟體中含有一個察覺不出或者無害的代碼段,當這個代碼段執行時,會破壞用戶安全 陷阱門 在系統或部件中設定了"機關",使得當提供特定輸入時產生違反安全策略的行為 抵賴 這是來自用戶的攻擊,如偽造對方來信,否認發過某條資訊
防火墻技術
網路級
作業層次低,效率高
應用級
作業層次高,效率低
