{"version":"https://jsonfeed.org/version/1.1","title":"苏迟但到的主页","home_page_url":"https://kexohproject.pages.dev","feed_url":"https://kexohproject.pages.dev/json/","description":"<p>你好，欢迎访问个人主页！</p><p>擅长密码学，安全分析，数字水印等技术。</p><p>你可以联系我通过:findmykexin@gmail.com或者知乎私信。</p><p>我的知乎链接：<a href=\"https://www.zhihu.com/people/su-chi-dan-dao\" rel=\"noopener noreferrer\" target=\"_blank\">苏迟但到 - 知乎 (zhihu.com)</a></p><p>我的github链接：<a href=\"https://github.com/kexinoh\" rel=\"noopener noreferrer\" target=\"_blank\">kexinoh</a></p>","icon":"https://kexohcdn.gptapi.cyou/kexohproject/production/images/channel-2e54d141ee195646ca12a9d16507a908.jpg","favicon":"https://kexohcdn.gptapi.cyou/kexohproject/production/images/favicon-340a2925d02a0386f3b954a032834917.jpg","authors":[{"name":"苏迟但到"}],"language":"zh-cn","items":[{"id":"32QSaKcKpIg","title":"为什么说 MD5 是不可逆的？","content_html":"<p data-pid=\"EYYE_z5J\">我对这些回答都很不满意，很显然大多数答主并没有深入了解MD5结构，只是了解的性质。他们并没有解释到底为什么MD5是不可逆的。</p><p data-pid=\"BPneBLk6\">我们来构造一个很简单的hash算法。</p><p data-pid=\"HMjpVWax\"><img src=\"https://www.zhihu.com/equation?tex=f%28x_%7Bi%7D%29%3Df%28x_%7Bi-1%7D%29%5Coplus+x_i%2Cf%28x_0%29%3D0\" alt=\"f(x_{i})=f(x_{i-1})\\oplus x_i,f(x_0)=0\" eeimg=\"1\"/> </p><p data-pid=\"oR85Nuf1\">如上式子所表达的迭代异或器，它也可以实现所谓的水浒传不可逆，但是一个关键问题来了</p><p data-pid=\"cAehOgj-\"><img src=\"https://www.zhihu.com/equation?tex=f%28x_1%29\" alt=\"f(x_1)\" eeimg=\"1\"/> 是可逆的。</p><p data-pid=\"AY1D-DwL\">它们都没有解释为什么<img src=\"https://www.zhihu.com/equation?tex=f%28x_1%29\" alt=\"f(x_1)\" eeimg=\"1\"/>是不可逆的，而从信息论角度解释是完全不全面且无意义的，不能解释MD5背后的密码学含义。</p><p data-pid=\"RB_YRdqh\">事实上，所有关于hash函数的处理的细节都在 <img src=\"https://www.zhihu.com/equation?tex=f%28x_1%29\" alt=\"f(x_1)\" eeimg=\"1\"/> 上，如果<img src=\"https://www.zhihu.com/equation?tex=f%28x_1%29\" alt=\"f(x_1)\" eeimg=\"1\"/>不可逆，那么只需要将构造一个迭代异或器就可以处理水浒传了，处理后续的分组只需要将它们进行简单的拼接就完成了</p><p data-pid=\"FXePDrz9\">这个问题<b>正确答案</b>应该是：<b>求解一个有512个未知变量的布尔方程组是困难的，因此是不可逆的。</b></p>","content_text":"我对这些回答都很不满意，很显然大多数答主并没有深入了解MD5结构，只是了解的性质。他们并没有解释到底为什么MD5是不可逆的。\n\n我们来构造一个很简单的hash算法。\n\nf(x_{i})=f(x_{i-1})\\oplus x_i,f(x_0)=0\n[https://www.zhihu.com/equation?tex=f%28x_%7Bi%7D%29%3Df%28x_%7Bi-1%7D%29%5Coplus+x_i%2Cf%28x_0%29%3D0]\n\n如上式子所表达的迭代异或器，它也可以实现所谓的水浒传不可逆，但是一个关键问题来了\n\nf(x_1) [https://www.zhihu.com/equation?tex=f%28x_1%29] 是可逆的。\n\n它们都没有解释为什么f(x_1)\n[https://www.zhihu.com/equation?tex=f%28x_1%29]是不可逆的，而从信息论角度解释是完全不全面且无意义的，不能解释MD5背后的密码学含义。\n\n事实上，所有关于hash函数的处理的细节都在 f(x_1) [https://www.zhihu.com/equation?tex=f%28x_1%29]\n上，如果f(x_1)\n[https://www.zhihu.com/equation?tex=f%28x_1%29]不可逆，那么只需要将构造一个迭代异或器就可以处理水浒传了，处理后续的分组只需要将它们进行简单的拼接就完成了\n\n这个问题正确答案应该是：求解一个有512个未知变量的布尔方程组是困难的，因此是不可逆的。","date_published":"2023-09-16T17:04:36.000Z","_microfeed":{"web_url":"https://kexohproject.pages.dev/i/md5-32QSaKcKpIg/","json_url":"https://kexohproject.pages.dev/i/32QSaKcKpIg/json/","rss_url":"https://kexohproject.pages.dev/i/32QSaKcKpIg/rss/","guid":"32QSaKcKpIg","status":"published","itunes:title":"New Article Title for iTunes","date_published_short":"Sat Sep 16 2023","date_published_ms":1694883876000}}],"_microfeed":{"microfeed_version":"0.1.2","base_url":"https://kexohproject.pages.dev","categories":[{"name":"Education","categories":[{"name":"Language Learning"}]},{"name":"Technology"}],"subscribe_methods":[{"name":"RSS","type":"rss","url":"https://kexohproject.pages.dev/rss/","image":"https://kexohproject.pages.dev/assets/brands/subscribe/rss.png","enabled":true,"editable":false,"id":"4KlfbtkEfzy"},{"name":"JSON","type":"json","url":"https://kexohproject.pages.dev/json/","image":"https://kexohproject.pages.dev/assets/brands/subscribe/json.png","enabled":true,"editable":false,"id":"DVFm7TYiNSq"}],"description_text":"你好，欢迎访问个人主页！\n\n擅长密码学，安全分析，数字水印等技术。\n\n你可以联系我通过:findmykexin@gmail.com或者知乎私信。\n\n我的知乎链接：苏迟但到 - 知乎 (zhihu.com)\n\n我的github链接：kexinoh","copyright":"©2024","itunes:type":"episodic","items_sort_order":"newest_first"}}