72 lines
1.5 KiB
JavaScript
72 lines
1.5 KiB
JavaScript
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/*!
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* algorithms/concat.js - Concat Key Derivation
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*
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* Copyright (c) 2015 Cisco Systems, Inc. See LICENSE file.
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*/
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"use strict";
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var CONSTANTS = require("./constants.js"),
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sha = require("./sha.js");
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function concatDeriveFn(name) {
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name = name.replace("CONCAT-", "");
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// NOTE: no nodejs/webcrypto/fallback model, since ConcatKDF is
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// implemented using the SHA algorithms
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var fn = function(key, props) {
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props = props || {};
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var keyLen = props.length,
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hashLen = CONSTANTS.HASHLENGTH[name];
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if (!keyLen) {
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return Promise.reject(new Error("invalid key length"));
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}
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// setup otherInfo
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if (!props.otherInfo) {
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return Promise.reject(new Error("invalid otherInfo"));
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}
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var otherInfo = props.otherInfo;
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var op = sha[name].digest;
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var N = Math.ceil(keyLen / hashLen),
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idx = 0,
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okm = [];
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function step() {
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if (N === idx++) {
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return Buffer.concat(okm).slice(0, keyLen);
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}
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var T = Buffer.alloc(4 + key.length + otherInfo.length);
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T.writeUInt32BE(idx, 0);
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key.copy(T, 4);
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otherInfo.copy(T, 4 + key.length);
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return op(T).then(function(result) {
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okm.push(result);
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return step();
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});
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}
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return step();
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};
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return fn;
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}
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// Public API
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// * [name].derive
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var concat = {};
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[
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"CONCAT-SHA-1",
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"CONCAT-SHA-256",
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"CONCAT-SHA-384",
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"CONCAT-SHA-512"
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].forEach(function(name) {
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concat[name] = {
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derive: concatDeriveFn(name)
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};
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});
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module.exports = concat;
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