element-web/src/CrossSigningManager.js

/*
Copyright 2019 The Matrix.org Foundation C.I.C.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

import Modal from './Modal';
import sdk from './index';
import MatrixClientPeg from './MatrixClientPeg';
import { deriveKey } from 'matrix-js-sdk/lib/crypto/key_passphrase';
import { decodeRecoveryKey } from 'matrix-js-sdk/lib/crypto/recoverykey';

// This stores the secret storage private keys in memory for the JS SDK. This is
// only meant to act as a cache to avoid prompting the user multiple times
// during the same session. It is considered unsafe to persist this to normal
// web storage. For platforms with a secure enclave, we will store this key
// there.
const secretStorageKeys = {};

export const getSecretStorageKey = async ({ keys: keyInfos }) => {
    const keyInfoEntries = Object.entries(keyInfos);
    if (keyInfoEntries.length > 1) {
        throw new Error("Multiple storage key requests not implemented");
    }
    const [name, info] = keyInfoEntries[0];

    // Check the in-memory cache
    if (secretStorageKeys[name]) {
        return [name, secretStorageKeys[name]];
    }

    const inputToKey = async ({ passphrase, recoveryKey }) => {
        if (passphrase) {
            return deriveKey(
                passphrase,
                info.passphrase.salt,
                info.passphrase.iterations,
            );
        } else {
            return decodeRecoveryKey(recoveryKey);
        }
    };
    const AccessSecretStorageDialog =
        sdk.getComponent("dialogs.secretstorage.AccessSecretStorageDialog");
    const { finished } = Modal.createTrackedDialog("Access Secret Storage dialog", "",
        AccessSecretStorageDialog,
        {
            keyInfo: info,
            checkPrivateKey: async (input) => {
                const key = await inputToKey(input);
                return MatrixClientPeg.get().checkSecretStoragePrivateKey(key, info.pubkey);
            },
        },
    );
    const [input] = await finished;
    if (!input) {
        throw new Error("Secret storage access canceled");
    }
    const key = await inputToKey(input);

    // Save to cache to avoid future prompts in the current session
    secretStorageKeys[name] = key;

    return [name, key];
};