52 lines
1.8 KiB
JavaScript
52 lines
1.8 KiB
JavaScript
/*
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* Copyright 2024 The Matrix.org Foundation C.I.C.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// salt for HKDF, with 8 bytes of zeros
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const zeroSalt = new Uint8Array(8);
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/**
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* Derive AES and HMAC keys from a master key.
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*
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* This is used for deriving secret storage keys: see https://spec.matrix.org/v1.11/client-server-api/#msecret_storagev1aes-hmac-sha2 (step 1).
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*
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* @param key
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* @param name
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*/
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export async function deriveKeys(key, name) {
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const hkdfkey = await globalThis.crypto.subtle.importKey("raw", key, {
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name: "HKDF"
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}, false, ["deriveBits"]);
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const keybits = await globalThis.crypto.subtle.deriveBits({
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name: "HKDF",
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salt: zeroSalt,
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// @ts-ignore: https://github.com/microsoft/TypeScript-DOM-lib-generator/pull/879
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info: new TextEncoder().encode(name),
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hash: "SHA-256"
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}, hkdfkey, 512);
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const aesKey = keybits.slice(0, 32);
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const hmacKey = keybits.slice(32);
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const aesProm = globalThis.crypto.subtle.importKey("raw", aesKey, {
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name: "AES-CTR"
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}, false, ["encrypt", "decrypt"]);
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const hmacProm = globalThis.crypto.subtle.importKey("raw", hmacKey, {
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name: "HMAC",
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hash: {
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name: "SHA-256"
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}
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}, false, ["sign", "verify"]);
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return Promise.all([aesProm, hmacProm]);
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}
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//# sourceMappingURL=deriveKeys.js.map
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