forked from mystiq/hydrogen-web
32 lines
1.3 KiB
TypeScript
32 lines
1.3 KiB
TypeScript
/**
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* Copyright (c) 2018 Jun Kurihara
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* Copyright 2020 The Matrix.org Foundation C.I.C.
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*
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* MIT LICENSE, See https://github.com/junkurihara/jscu/blob/develop/packages/js-crypto-hkdf/LICENSE
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* Based on https://github.com/junkurihara/jscu/blob/develop/packages/js-crypto-hkdf/src/hkdf.ts
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*/
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import type {Crypto} from "../../platform/web/dom/Crypto.js";
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// forked this code to make it use the cryptoDriver for HMAC that is more backwards-compatible
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export async function hkdf(cryptoDriver: Crypto, key: Uint8Array, salt: Uint8Array, info: Uint8Array, hash: "SHA-256" | "SHA-512", length: number): Promise<Uint8Array> {
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length = length / 8;
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const len = cryptoDriver.digestSize(hash);
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// RFC5869 Step 1 (Extract)
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const prk = await cryptoDriver.hmac.compute(salt, key, hash);
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// RFC5869 Step 2 (Expand)
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let t = new Uint8Array([]);
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const okm = new Uint8Array(Math.ceil(length / len) * len);
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for(let i = 0; i < Math.ceil(length / len); i++){
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const concat = new Uint8Array(t.length + info.length + 1);
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concat.set(t);
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concat.set(info, t.length);
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concat.set(new Uint8Array([i+1]), t.length + info.length);
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t = await cryptoDriver.hmac.compute(prk, concat, hash);
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okm.set(t, len * i);
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}
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return okm.slice(0, length);
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}
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