CyberChef/src/core/operations/ToBase85.mjs

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/**
* @author PenguinGeorge [george@penguingeorge.com]
* @copyright Crown Copyright 2018
* @license Apache-2.0
*/
import Operation from "../Operation";
import OperationError from "../errors/OperationError";
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import Utils from "../Utils";
import {alphabetName, ALPHABET_OPTIONS} from "../lib/Base85";
/**
* To Base85 operation
*/
class ToBase85 extends Operation {
/**
* To Base85 constructor
*/
constructor() {
super();
this.name = "To Base85";
this.module = "Default";
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this.description = "Base85 (also called Ascii85) is a notation for encoding arbitrary byte data. It is usually more efficient that Base64.<br><br>This operation encodes data in an ASCII string (with an alphabet of your choosing, presets included).<br><br>e.g. <code>hello world</code> becomes <code>BOu!rD]j7BEbo7</code><br><br>Base85 is commonly used in Adobe's PostScript and PDF file formats.<br><br><strong>Options</strong><br><u>Alphabet</u><ul><li>Standard - The standard alphabet, referred to as Ascii85</li><li>Z85 (ZeroMQ) - A string-safe variant of Base85, which avoids quote marks and backslash characters</li><li>IPv6 - A variant of Base85 suitable for encoding IPv6 addresses (RFC 1924)</li></ul><u>Include delimiter</u><br>Adds a '<~' and '~>' delimiter to the start and end of the data. This is standard for Adobe's implementation of Base85.";
this.infoURL = "https://wikipedia.org/wiki/Ascii85";
this.inputType = "byteArray";
this.outputType = "string";
this.args = [
{
name: "Alphabet",
type: "editableOption",
value: ALPHABET_OPTIONS
},
{
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name: "Include delimeter",
type: "boolean",
value: false
}
];
}
/**
* @param {byteArray} input
* @param {Object[]} args
* @returns {string}
*/
run(input, args) {
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const alphabet = Utils.expandAlphRange(args[0]).join(""),
encoding = alphabetName(alphabet),
includeDelim = args[1];
let result = "";
if (alphabet.length !== 85 ||
[].unique.call(alphabet).length !== 85) {
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throw new OperationError("Error: Alphabet must be of length 85");
}
if (input.length === 0) return "";
let block;
for (let i = 0; i < input.length; i += 4) {
block = (
((input[i]) << 24) +
((input[i + 1] || 0) << 16) +
((input[i + 2] || 0) << 8) +
((input[i + 3] || 0))
) >>> 0;
if (encoding !== "Standard" || block > 0) {
let digits = [];
for (let j = 0; j < 5; j++) {
digits.push(block % 85);
block = Math.floor(block / 85);
}
digits = digits.reverse();
if (input.length < i + 4) {
digits.splice(input.length - (i + 4), 4);
}
result += digits.map(digit => alphabet[digit]).join("");
} else {
result += (encoding === "Standard") ? "z" : null;
}
}
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return includeDelim ? `<~${result}~>` : result;
}
}
export default ToBase85;