Hugh Nimmo-Smith
ff1db2b538
* Bump eslint-plugin-matrix-org to enable @typescript-eslint/consistent-type-imports rule * Re-lint after merge
55 lines
2.2 KiB
TypeScript
55 lines
2.2 KiB
TypeScript
/*
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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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import { decodeBase64 } from "../base64.ts";
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import { deriveKeys } from "./internal/deriveKeys.ts";
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import { type AESEncryptedSecretStoragePayload } from "../@types/AESEncryptedSecretStoragePayload.ts";
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/**
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* Decrypt an AES-encrypted Secret Storage item.
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*
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* @param data - the encrypted data, returned by {@link utils/encryptAESSecretStorageItem.default | encryptAESSecretStorageItem}.
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* @param key - the encryption key to use as an input to the HKDF function which is used to derive the AES key. Must
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* be the same as provided to {@link utils/encryptAESSecretStorageItem.default | encryptAESSecretStorageItem}.
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* @param name - the name of the secret. Also used as an input to the HKDF operation which is used to derive the AES
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* key, so again must be the same as provided to {@link utils/encryptAESSecretStorageItem.default | encryptAESSecretStorageItem}.
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*/
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export default async function decryptAESSecretStorageItem(
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data: AESEncryptedSecretStoragePayload,
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key: Uint8Array,
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name: string,
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): Promise<string> {
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const [aesKey, hmacKey] = await deriveKeys(key, name);
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const ciphertext = decodeBase64(data.ciphertext);
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if (!(await globalThis.crypto.subtle.verify({ name: "HMAC" }, hmacKey, decodeBase64(data.mac), ciphertext))) {
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throw new Error(`Error decrypting secret ${name}: bad MAC`);
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}
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const plaintext = await globalThis.crypto.subtle.decrypt(
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{
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name: "AES-CTR",
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counter: decodeBase64(data.iv),
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length: 64,
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},
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aesKey,
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ciphertext,
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);
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return new TextDecoder().decode(new Uint8Array(plaintext));
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}
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