Vigenère Cipher Helper - codewars

Vigenère Cipher Helper - codewars

月光魔力鸭

2019-01-11 19:41 阅读 537 喜欢 1 维吉尼亚加解密 codewars

Vigenère Cipher Helper

The Vigenère cipher is a classic cipher originally developed by Italian cryptographer Giovan Battista Bellaso and published in 1553. It is named after a later French cryptographer Blaise de Vigenère, who had developed a stronger autokey cipher (a cipher that incorporates the message of the text into the key).
The cipher is easy to understand and implement, but survived three centuries of attempts to break it, earning it the nickname "le chiffre indéchiffrable" or "the indecipherable cipher."
From Wikipedia:

The Vigenère cipher is a method of encrypting alphabetic text by using a series of different Caesar ciphers based on the letters of a keyword. It is a simple form of polyalphabetic substitution. ... In a Caesar cipher, each letter of the alphabet is shifted along some number of places; for example, in a Caesar cipher of shift 3, A would become D, B would become E, Y would become B and so on. The Vigenère cipher consists of several Caesar ciphers in sequence with different shift values.

Assume the key is repeated for the length of the text, character by character. Note that some implementations repeat the key over characters only if they are part of the alphabet -- this is not the case here.
The shift is derived by applying a Caesar shift to a character with the corresponding index of the key in the alphabet.
Visual representation:
"my secret code i want to secure"  // message
"passwordpasswordpasswordpasswor"  // key
Write a class that, when given a key and an alphabet, can be used to encode and decode from the cipher.

Example

var alphabet = 'abcdefghijklmnopqrstuvwxyz';
var key = 'password';

// creates a cipher helper with each letter substituted
// by the corresponding character in the key
var c = new VigenèreCipher(key, alphabet);

c.encode('codewars'); // returns 'rovwsoiv'
c.decode('laxxhsj');  // returns 'waffles'
Any character not in the alphabet must be left as is. For example (following from above):
c.encode('CODEWARS'); // returns 'CODEWARS'

There's my solution below

function VigenèreCipher(key,abc){
    this.encode = function(str){
        //对str进行分割,确认是否在字母表中,然后按照
        return str.split('').map((item,i)=>{
            //按照key和abc中的位置,进行移动找到当前所在的位置
            return abc.indexOf(item) > -1 ? 
            abc[(abc.indexOf(item) + abc.indexOf(key[i % key.length])) % abc.length]
            : item;
        }).join('');
    }
    this.decode = function(str){
        //与encode相反,获得坐标在移动回来
        return str.split('').map((item,i)=>{
            //按照key和abc中的位置,进行移动找到当前所在的位置
            return abc.indexOf(item) > -1 ? 
            abc[( abc.length + abc.indexOf(item) - abc.indexOf(key[i % key.length]) ) % abc.length]
            : item;
        }).join('');
    }
}

Question From : https://www.codewars.com/kata/52d1bd3694d26f8d6e0000d3/train/javascript

转载请注明出处: https://chrunlee.cn/article/code-war-cipher-helper.html


感谢支持!

赞赏支持
提交评论
评论信息 (请文明评论)
暂无评论,快来快来写想法...
推荐
通过jspdf ,我们可以将页面或图片生成pdf下载下来,如果是一些复杂的页面,我们可以将页面转成图片,然后把图片加入到pdf中,生成并下载。
需求如下:有一张大图,需要显示大图中的一小部分,目前能知道的时候小图的宽高和坐标,同时大图有一个旋转角度可以知道,目标就是把小图正确的显示出来。
之前一直没面试过前端,今天有一个,先整理下需要问的问题和答案。这里都是一些简单的问题,关于当下比较流行的框架并没有涉及到..
突然来了一个调研任务,想要实现一个类似3D虚拟展厅类似的需求,主要就是放一些学生的作品,然后预览啥的,效果还是要全景的效果。 经过一番调查,最终锁定了以前从未接触过的krpano。
在开发过程中多个页面使用的一个小工具类,简单完善了下,还算不错,给各位提供下小思路。
通过canvas可以进行画图实现一些动画效果等,今天练习下通过canvas来实现一个简易的电子画板,可以在白板上进行画画,然后指定不同的颜色、线条粗细,加载不同的背景以及擦除效果。
对于web开发过程中的JS对象 Array ,我们真的充分使用了么?是不是理解了Array的全部?能够在合适的地点调用合适的函数,使用合适的属性?
有时候浏览网页经常会看见一些页面出现一些打字的效果,那么是怎么实现的呢?