Vigenère Cipher Helper - codewars

Vigenère Cipher Helper - codewars

月光魔力鸭

2019-01-11 19:41 阅读 373 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
在我们通过canvs画图的时候经常会用到圆,且需要计算出圆上某点的坐标,由于我数学没学好,总是记不得怎么获取,这里记录下,加深记忆
web网站上总会有在文本域中提交代码的操作,那么如何处理呢?
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..
java 对象中有很多引用,甚至会出现循环引用,比如 user 对象中有 school 对象,school 对象中又有 user 对象,这样在对 user 对象序列化的时候,就会出现死循环,导致内存溢出。通过一定的方式,将每个对象增加ID 和 REF 引用标识最终可以解决这个问题
本文概括了递归、闭包、原型、继承,理清这些基本的概念,有助于你接纳更多的东西,我们会在下一个章节对函数进行更深入的讨论。
关于web打印,需要对页面内容进行页面样式设置,呈现出分页的样子,同时对于题目中的图片或表格尽量不分到两个页面中,因此实现了一个jquery的web打印插件,当然,这个插件目前只适用于部分情况,仅供借鉴
Question from codewar,about all of array combinations.
问题是由一个BUG引起的,功能中有使用国际化组件,用的是jquery.i18n,在chrome上、ff上都没有什么问题,问题出在了IE上。万恶的IE..