從崩潰的選課系統，論爲什麼更安全的 HTTPS 協議沒有被全面採用

{"type":"doc","content":[{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"🎓 盡人事，聽天命。博主東南大學研究生在讀，熱愛健身和籃球，正在爲兩年後的秋招準備中，樂於分享技術相關的所見所得，關注公衆號 @ ","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"飛天小牛肉","attrs":{}},{"type":"text","text":"，第一時間獲取文章更新，成長的路上我們一起進步","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"🎁 本文已收錄於 ","attrs":{}},{"type":"link","attrs":{"href":"https://gitee.com/veal98/CS-Wiki","title":null},"content":[{"type":"text","text":"CS-Wiki（Gitee 官方推薦項目，現已 0.9k star)","attrs":{}}],"marks":[{"type":"strong"}]},{"type":"text","text":"，致力打造完善的後端知識體系，在技術的路上少走彎路，歡迎各位小夥伴前來交流學習","attrs":{}}]}],"attrs":{}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"0. 前言","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"上一篇文章詳細講解了 HTTP 的相關原理，我們已經瞭解到了 HTTP 具有非常優秀和方便的一面，然而，HTTP 並非一個安全的協議。大家平常瀏覽網頁的時候應該也能注意到，使用 HTTP 協議的網站，瀏覽器都會認定這是一個不安全的網站，提醒用戶注意防範（即便這是我們學校的選課系統）。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/6a/6a5ecde82ec3a9f197ccae3d19e73c61.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"當然，這個不安全的含義指的是你在該網頁輸入的信息可能會被外界攻擊者以非正常手段竊取，而不是說會被這個網頁的開發者獲取，畢竟瀏覽器咋能判斷這個網頁開發者是否存有異心，這個需要用戶自行判斷（手動滑稽 😮）","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"那麼爲了克服 HTTP 的缺點，確保 Web 的安全，HTTPS 就應用而生了。可以看見，使用 HTTPS 協議的網頁，地址欄前面都會有把小鎖，表示這是一個加密安全的網站，你的信息發送到此站點時是保密的。而且 Google、Baidu 等搜索引擎巨頭對於 HTTPS 網站都會給到更好的搜索排名。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/ec/ec4d34a9d7027959692b2e0f935aecb8.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"本文會先解釋 HTTP 爲什麼是不安全的，然後講解 HTTPS 爲了保證 Web 的安全提供了哪些手段，最後再揭曉謎底，爲什麼更安全的 HTTPS 協議在互聯網上沒有被全面採用。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"1. 不安全的 HTTP","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通過上面那張圖我們已經知道，對於使用 HTTP 的網站，瀏覽器就會提醒我們請勿在此網站上輸入任何敏感信息，否則可能會被攻擊者竊取。沒錯，這就是 HTTP 協議不安全的表現，而且，僅僅是其中之一，HTTP 的不安全性體現在很多方面，例舉如下：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通信使用明文（不加密），內容可能被","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"竊聽","attrs":{}}]}],"attrs":{}},{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"不驗證通信對方的身份，因此有可能遭遇","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"僞裝","attrs":{}}]}],"attrs":{}},{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"無法證明報文的完整性，所以有可能被","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"篡改","attrs":{}}]}],"attrs":{}}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"當然，這些問題不僅在 HTTP 上出現，其他未加密的協議中也存在類似問題","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"下面我們詳細分析下上述問題出現的原因。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"① 內容被竊聽","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"所謂互聯網，是由能連接到全世界的網絡組成的，萬物互聯，無論世界哪個角落的服務器在和客戶端進行通信時，在此通信線路上的網絡設備、光纜、計算機都可能會遭到惡意窺視行爲。也就是說，互聯網上的任何角落都存在通信內容被竊聽的風險。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"而由於 ","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"HTTP 本身不具備加密的功能","attrs":{}},{"type":"text","text":"，所以也無法做到對 HTTP 請求和響應報文進行加密。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"但是！","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"即使是加密過的通信內容，也會被窺視到，這點和未加密的通信是相同的","attrs":{}},{"type":"text","text":"。只能說經過加密後的內容，即便被攻擊者窺視到，他也可能無法破解其中的含義罷了，但是加密處理後的報文信息本身還是會被看到的，這點大家不要混淆了。加密後的內容尚且如此，更別說未加密的了。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"② 身份被僞裝","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"HTTP 的請求和響應不會對通信方進行確認","attrs":{}},{"type":"text","text":"，也就是說任何人都可以發起請求，而服務器對請求者來者不拒，只要接收到請求，就會返回一個響應。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/6f/6fe62071a42c25a9344d9b38b62ab5f0.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"顯然，正是由於 HTTP 的這種簡單性，導致瞭如下隱患：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"1）客戶端發送的 HTTP 請求報文可能到達的並非真正的目的服務器，可能是已僞裝的服務器","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/75/75b47c391011cbd74e8e23c44097f59b.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"2）服務器返回的 HTTP 響應報文可能也並沒有被正確的客戶端所接收，可能是已僞裝的客戶端","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/fa/fae8163b69a3014952a72b442e52068b.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"3）無法確定正在通信的對方是否具備訪問權限","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"4）無法判定請求來自何方，出自誰手","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"5）即使是無意義的請求也會照單全收","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"③ 報文被篡改","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"HTTP 無法證明報文的完整性","attrs":{}},{"type":"text","text":"，所謂完整性就是指信息的準確度。若無法證明完整性，在 HTTP 請求或響應 送出之後直到對方接收的這段時間內，即使請求或響應的內容遭到攻擊者篡改，也沒有辦法獲悉。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通俗來說，","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"HTTP 沒有辦法確認發送出去的請求和接收到的請求是否一致","attrs":{}},{"type":"text","text":"。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"舉個例子，你從某個使用 HTTP 的非正規網站上下載微信 APP，存放在服務器上的文件確實是微信 APP，但是，在你下載的過程當中，攻擊者攻擊了這個網站，你正在傳輸的文件內容被篡改成了其他文件，而在這個過程中，你是完全察覺不到的。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"像這樣的在請求或響應在傳輸途中，遭受攻擊者攔截並篡改內容的攻擊稱爲","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"中間人攻擊","attrs":{}},{"type":"text","text":"（Main-in-the-Middle attack, MITM）。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/d8/d8113cd17bcf92af95c15688579137c5.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"2. 安全的 HTTPS","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"HTTPS 協議並非應用層的一個新協議，只是 HTTP 通信接口部分用 SSL（Secure Socket Layer）和 TLS（Transport Layer Security）協議代替而已。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通常 HTTP 是直接和 TCP 進行通信的，當使用 SSL 時，則演變成先和 SSL 通信，再由 SSL 和 TCP 進行通信。簡而言之。","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"所謂 HTTPS，就是身批 SSL 協議外殼的 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不安全問題的。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/d4/d481496c3e80dd2680fe8cfecb5da67c.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"另外，SSL 是獨立於 HTTP 協議的，所有運行在應用層的協議都可以配合 SSL 協議使用。可以說，SSL 協議是當今世界上應用最爲廣泛的網絡安全技術。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"那麼，針對上述 HTTP 的三個安全性問題，我們來看看 HTTPS 或者說 SSL 到底提供了哪些解決方案。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"① 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