mirror of https://github.com/gchq/CyberChef.git
54 lines
1.4 KiB
JavaScript
54 lines
1.4 KiB
JavaScript
/**
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* @author n1474335 [n1474335@gmail.com]
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* @copyright Crown Copyright 2016
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* @license Apache-2.0
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*/
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import Operation from "../Operation";
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import Utils from "../Utils";
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/**
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* Adler-32 Checksum operation
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*/
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class Adler32Checksum extends Operation {
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/**
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* Adler32Checksum constructor
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*/
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constructor() {
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super();
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this.name = "Adler-32 Checksum";
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this.module = "Crypto";
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this.description = "Adler-32 is a checksum algorithm which was invented by Mark Adler in 1995, and is a modification of the Fletcher checksum. Compared to a cyclic redundancy check of the same length, it trades reliability for speed (preferring the latter).<br><br>Adler-32 is more reliable than Fletcher-16, and slightly less reliable than Fletcher-32.";
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this.infoURL = "https://wikipedia.org/wiki/Adler-32";
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this.inputType = "byteArray";
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this.outputType = "string";
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this.args = [];
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}
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/**
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* @param {byteArray} input
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* @param {Object[]} args
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* @returns {string}
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*/
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run(input, args) {
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const MOD_ADLER = 65521;
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let a = 1,
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b = 0;
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for (let i = 0; i < input.length; i++) {
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a += input[i];
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b += a;
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}
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a %= MOD_ADLER;
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b %= MOD_ADLER;
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return Utils.hex(((b << 16) | a) >>> 0, 8);
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}
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}
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export default Adler32Checksum;
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