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56 lines
2.4 KiB
TypeScript
56 lines
2.4 KiB
TypeScript
/*
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Copyright 2016, 2018, 2021 The Matrix.org Foundation C.I.C.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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// Pull in the encryption lib so that we can decrypt attachments.
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import encrypt from 'browser-encrypt-attachment';
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import { mediaFromContent } from "../customisations/Media";
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import { IEncryptedFile, IMediaEventInfo } from "../customisations/models/IMediaEventContent";
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import { getBlobSafeMimeType } from "./blobs";
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/**
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* Decrypt a file attached to a matrix event.
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* @param {IEncryptedFile} file The encrypted file information taken from the matrix event.
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* This passed to [link]{@link https://github.com/matrix-org/browser-encrypt-attachments}
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* as the encryption info object, so will also have the those keys in addition to
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* the keys below.
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* @param {IMediaEventInfo} info The info parameter taken from the matrix event.
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* @returns {Promise<Blob>} Resolves to a Blob of the file.
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*/
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export function decryptFile(
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file: IEncryptedFile,
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info?: IMediaEventInfo,
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): Promise<Blob> {
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const media = mediaFromContent({ file });
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// Download the encrypted file as an array buffer.
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return media.downloadSource().then((response) => {
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return response.arrayBuffer();
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}).then((responseData) => {
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// Decrypt the array buffer using the information taken from
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// the event content.
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return encrypt.decryptAttachment(responseData, file);
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}).then((dataArray) => {
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// Turn the array into a Blob and give it the correct MIME-type.
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// IMPORTANT: we must not allow scriptable mime-types into Blobs otherwise
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// they introduce XSS attacks if the Blob URI is viewed directly in the
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// browser (e.g. by copying the URI into a new tab or window.)
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// See warning at top of file.
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let mimetype = info?.mimetype ? info.mimetype.split(";")[0].trim() : '';
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mimetype = getBlobSafeMimeType(mimetype);
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return new Blob([dataArray], { type: mimetype });
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});
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}
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