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Cifrado de Vigenere
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class VigenereCipher { | |
constructor(key, alphabet){ | |
this.alphabet = alphabet; | |
this.key = key; | |
this.l = alphabet.length; | |
} | |
repeat_key(length){ | |
let new_key = this.key; | |
while(new_key.length < length){ | |
new_key = new_key.repeat(2) | |
} | |
return new_key.slice(0, length + 1); | |
} | |
encode(str) { | |
const key = this.repeat_key(str.length) | |
return str | |
.split("") | |
.map((x, i) => { | |
const xi = this.alphabet.indexOf(x); | |
const k = key[i]; | |
const ki = this.alphabet.indexOf(k); | |
if(xi === -1) return x; | |
const ei = (xi + ki) % this.l | |
return this.alphabet[ei]; | |
}) | |
.join(""); | |
} | |
decode(str) { | |
const key = this.repeat_key(str.length) | |
return str | |
.split("") | |
.map((c, i) => { | |
const ci = this.alphabet.indexOf(c); | |
const k = key[i]; | |
const ki = this.alphabet.indexOf(k); | |
if(ci === -1) return c; | |
let di; | |
if((ci - ki) < 0) di = di = (ci - ki + this.l) % this.l; | |
else di = (ci - ki) % this.l; | |
return this.alphabet[di]; | |
}) | |
.join(""); | |
} | |
} |
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