Zengchang's profileHow many numbers contain...PhotosBlogListsMore ![]() | Help |
How many numbers contain the digit 3?An amazing answer - almost all the numbers |
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October 04 A quote of Game TheoryA wonderful quote about the nature of Game Theory
by Michael Mandel, on Kahneman and Smith 2002 Nobel Prize in Economics. July 15 Talking about 季羡林的话
Quote 季羡林的话 June 22 Talking about 葡萄忧伤出售--四元两斤 (只是叙事,不玩文字。)From a friend's friend.
Quote 葡萄忧伤出售--四元两斤 (只是叙事,不玩文字。) 谈论 对比阅读:英国民主不是一个好东西 (ZT)Cited from a friend, I have no comments yet. :) 引用 对比阅读:英国民主不是一个好东西 April 14 Adi Shamir来北航后今天第一次听有点质量的报告, Adi Shamir 是密码学中的经典算法RSA中的S, (RSA-Riverst, Shamir and Adleman). Turing Award的获得者。
如果你对RSA感兴趣, 下面是一个例子,是如何用public key把一个数字加密后, 用一个private key来解密。
The private key is (n = 3233, d = 2753). The decryption function is:
To decrypt c = 855, we calculate
可是由于RSA算法的计算量比较大(幂的计算为主),一般用 square-and-multiply 算法。 一个十分聪明的破密方法是: 由于计算机在执行 square 运算和 multiply 运算时的噪声不一样, 用电量不一样。 可以从噪音信号和用电量变化中找到倪端来计算private key中的 d。 的确是十分聪明的办法!!如果用数学方法解。。。。呵呵,你可以自己试试。
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