mirror of https://github.com/gchq/CyberChef.git
50 lines
1.4 KiB
JavaScript
50 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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* Fletcher-16 Checksum operation
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*/
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class Fletcher16Checksum extends Operation {
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/**
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* Fletcher16Checksum constructor
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*/
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constructor() {
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super();
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this.name = "Fletcher-16 Checksum";
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this.module = "Crypto";
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this.description = "The Fletcher checksum is an algorithm for computing a position-dependent checksum devised by John Gould Fletcher at Lawrence Livermore Labs in the late 1970s.<br><br>The objective of the Fletcher checksum was to provide error-detection properties approaching those of a cyclic redundancy check but with the lower computational effort associated with summation techniques.";
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this.infoURL = "https://wikipedia.org/wiki/Fletcher%27s_checksum#Fletcher-16";
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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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let a = 0,
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b = 0;
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for (let i = 0; i < input.length; i++) {
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a = (a + input[i]) % 0xff;
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b = (b + a) % 0xff;
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}
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return Utils.hex(((b << 8) | a) >>> 0, 4);
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}
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}
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export default Fletcher16Checksum;
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