Differential D7233 Diff 24533 native/media/encryption-utils.js

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native/media/encryption-utils.js

// @flow		// @flow

import filesystem from 'react-native-fs';		import filesystem from 'react-native-fs';

import { base64FromIntArray, hexToUintArray } from 'lib/media/data-utils.js';		import {
import { fileInfoFromData, readableFilename } from 'lib/media/file-utils.js';		base64FromIntArray,
import type { MediaMissionFailure } from 'lib/types/media-types.js';		uintArrayToHexString,
		hexToUintArray,
		} from 'lib/media/data-utils.js';
		import {
		replaceExtension,
		fileInfoFromData,
		readableFilename,
		} from 'lib/media/file-utils.js';
		import type {
		MediaMissionFailure,
		EncryptFileMediaMissionStep,
		} from 'lib/types/media-types.js';
import { getMessageForException } from 'lib/utils/errors.js';		import { getMessageForException } from 'lib/utils/errors.js';
import { unpad } from 'lib/utils/pkcs7-padding.js';		import { pad, unpad, calculatePaddedLength } from 'lib/utils/pkcs7-padding.js';

import { temporaryDirectoryPath } from './file-utils.js';		import { temporaryDirectoryPath } from './file-utils.js';
import { getFetchableURI } from './identifier-utils.js';		import { getFetchableURI } from './identifier-utils.js';
import * as AES from '../utils/aes-crypto-module.js';		import * as AES from '../utils/aes-crypto-module.js';

const PADDING_THRESHOLD = 5000000; // we don't pad files larger than this		const PADDING_THRESHOLD = 5000000; // we don't pad files larger than this

		type EncryptedFileResult = {
		+success: true,
		+uri: string,
		+encryptionKey: string,
		};

		/**
		* Encrypts a single file and returns the encrypted file URI
		* and the encryption key. The encryption key is returned as a hex string.
		* The encrypted file is written to the same directory as the original file,
		* with the same name, but with the extension ".dat".
		*
		* @param uri uri to the file to encrypt
		* @returns encryption result along with mission steps
		*/
		async function encryptFile(uri: string): Promise<{
		steps: $ReadOnlyArray<EncryptFileMediaMissionStep>,
		result: MediaMissionFailure \| EncryptedFileResult,
		}> {
		let success = true,
		exceptionMessage;
		const steps: EncryptFileMediaMissionStep[] = [];
		const destination = replaceExtension(uri, 'dat');

		// Step 1. Read the file
		const startOpenFile = Date.now();
		let data;
		try {
		const response = await fetch(getFetchableURI(uri));
		const buffer = await response.arrayBuffer();
		data = new Uint8Array(buffer);
		} catch (e) {
		success = false;
		exceptionMessage = getMessageForException(e);
		}
		steps.push({
		step: 'read_plaintext_file',
		file: uri,
		time: Date.now() - startOpenFile,
		success,
		exceptionMessage,
		});
		if (!success \|\| !data) {
		return {
		steps,
		result: { success: false, reason: 'fetch_failed' },
		};
		}

		// Step 2. Encrypt the file
		const startEncrypt = Date.now();
		const paddedLength = calculatePaddedLength(data.byteLength);
		const shouldPad = paddedLength <= PADDING_THRESHOLD;
		let key, encryptedData;
		try {
		const plaintextData = shouldPad ? pad(data) : data;
		key = AES.generateKey();
		encryptedData = AES.encrypt(key, plaintextData);
		} catch (e) {
		success = false;
		exceptionMessage = getMessageForException(e);
		}
		steps.push({
		step: 'encrypt_data',
		dataSize: encryptedData?.byteLength ?? -1,
		isPadded: shouldPad,
		time: Date.now() - startEncrypt,
		success,
		exceptionMessage,
		});
		if (!success \|\| !encryptedData \|\| !key) {
		return {
		steps,
		result: { success: false, reason: 'encryption_failed' },
		};
		}

		// Step 3. Write the encrypted file
		const startWriteFile = Date.now();
		try {
		const targetBase64 = base64FromIntArray(encryptedData);
		await filesystem.writeFile(destination, targetBase64, 'base64');
		} catch (e) {
		success = false;
		exceptionMessage = getMessageForException(e);
		}
		steps.push({
		step: 'write_encrypted_file',
		file: destination,
		time: Date.now() - startWriteFile,
		success,
		exceptionMessage,
		});
		if (!success) {
		return {
		steps,
		result: { success: false, reason: 'write_file_failed' },
		};
		}

		return {
		steps,
		result: {
		success: true,
		uri: destination,
		encryptionKey: uintArrayToHexString(key),
		},
		};
		}

type DecryptFileStep =		type DecryptFileStep =
\| {		\| {
+step: 'fetch_file',		+step: 'fetch_file',
+file: string,		+file: string,
+time: number,		+time: number,
+success: boolean,		+success: boolean,
+exceptionMessage: ?string,		+exceptionMessage: ?string,
}		}
▲ Show 20 Lines • Show All 158 Lines • ▼ Show 20 Lines	): Promise<{
}		}

return {		return {
steps,		steps,
result: { success: true, uri },		result: { success: true, uri },
};		};
}		}

export { decryptMedia };		export { encryptFile, decryptMedia };