为什么S盒输入比其输出长？ [英] Why is an s-box input longer than its output?

问题描述

我不明白这篇文章中的额外资料来源关于s-boxes。为什么s-box没有输入相同的位数作为输出？

I don't understand where the extra bits are coming from in this article about s-boxes. Why doesn't the s-box take in the same number of bits for input as output?

推荐答案

箱子工作。它们可以是m * n ==> m位输入，n位输出。
例如，在 AES S-box中，输入中的位数为等于输出中的位数。

It is the way s-boxes work. They can be m * n ==> m bit input , n bit output. For example, in the AES S-box the number of bits in input is equal to the number of bits in output.

在 DES ，m = 6和n = 4。

In DES, m=6 and n=4.

在DES的第一阶段，输入从32扩展到48位。因此，通过应用一轮S盒替换再次将其减少到32位。因此，这里没有信息丢失。

The input is expanded from 32 to 48 bits in the first stages of DES. So it is be reduced to 32 bits again by applying one round of S-box substitution. Thus no information is lost here.

维基百科的文章本身可能有点令人困惑。这将使人们认为信息丢失。您应该阅读文章结合使用s-box的一些加密算法的实现细节。

The Wikipedia article on itself can be a bit confusing. It will make people think that information is lost. You should read the article in conjuncture with implementation details of some encryption algorithm using s-boxes.

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