move crypto code to hush.js
This commit is contained in:
Girish Ramakrishnan
+225
@@ -0,0 +1,225 @@
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'use strict';
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exports = module.exports = {
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EncryptStream,
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DecryptStream,
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encryptFilePath,
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decryptFilePath,
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createReadStream,
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createWriteStream
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};
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const assert = require('assert'),
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BoxError = require('./boxerror.js'),
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crypto = require('crypto'),
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debug = require('debug')('box:hush'),
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fs = require('fs'),
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progressStream = require('progress-stream'),
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TransformStream = require('stream').Transform;
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class EncryptStream extends TransformStream {
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constructor(encryption) {
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super();
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this._headerPushed = false;
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this._iv = crypto.randomBytes(16);
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this._cipher = crypto.createCipheriv('aes-256-cbc', Buffer.from(encryption.dataKey, 'hex'), this._iv);
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this._hmac = crypto.createHmac('sha256', Buffer.from(encryption.dataHmacKey, 'hex'));
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}
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pushHeaderIfNeeded() {
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if (!this._headerPushed) {
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const magic = Buffer.from('CBV2');
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this.push(magic);
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this._hmac.update(magic);
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this.push(this._iv);
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this._hmac.update(this._iv);
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this._headerPushed = true;
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}
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}
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_transform(chunk, ignoredEncoding, callback) {
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this.pushHeaderIfNeeded();
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try {
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const crypt = this._cipher.update(chunk);
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this._hmac.update(crypt);
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callback(null, crypt);
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} catch (error) {
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callback(error);
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}
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}
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_flush(callback) {
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try {
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this.pushHeaderIfNeeded(); // for 0-length files
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const crypt = this._cipher.final();
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this.push(crypt);
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this._hmac.update(crypt);
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callback(null, this._hmac.digest()); // +32 bytes
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} catch (error) {
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callback(error);
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}
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}
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}
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class DecryptStream extends TransformStream {
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constructor(encryption) {
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super();
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this._key = Buffer.from(encryption.dataKey, 'hex');
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this._header = Buffer.alloc(0);
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this._decipher = null;
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this._hmac = crypto.createHmac('sha256', Buffer.from(encryption.dataHmacKey, 'hex'));
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this._buffer = Buffer.alloc(0);
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}
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_transform(chunk, ignoredEncoding, callback) {
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const needed = 20 - this._header.length; // 4 for magic, 16 for iv
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if (this._header.length !== 20) { // not gotten header yet
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this._header = Buffer.concat([this._header, chunk.slice(0, needed)]);
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if (this._header.length !== 20) return callback();
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if (!this._header.slice(0, 4).equals(new Buffer.from('CBV2'))) return callback(new BoxError(BoxError.CRYPTO_ERROR, 'Invalid magic in header'));
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const iv = this._header.slice(4);
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this._decipher = crypto.createDecipheriv('aes-256-cbc', this._key, iv);
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this._hmac.update(this._header);
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}
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this._buffer = Buffer.concat([ this._buffer, chunk.slice(needed) ]);
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if (this._buffer.length < 32) return callback(); // hmac trailer length is 32
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try {
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const cipherText = this._buffer.slice(0, -32);
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this._hmac.update(cipherText);
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const plainText = this._decipher.update(cipherText);
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this._buffer = this._buffer.slice(-32);
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callback(null, plainText);
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} catch (error) {
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callback(error);
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}
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}
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_flush (callback) {
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if (this._buffer.length !== 32) return callback(new BoxError(BoxError.CRYPTO_ERROR, 'Invalid password or tampered file (not enough data)'));
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try {
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if (!this._hmac.digest().equals(this._buffer)) return callback(new BoxError(BoxError.CRYPTO_ERROR, 'Invalid password or tampered file (mac mismatch)'));
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const plainText = this._decipher.final();
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callback(null, plainText);
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} catch (error) {
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callback(error);
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}
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}
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}
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function encryptFilePath(filePath, encryption) {
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assert.strictEqual(typeof filePath, 'string');
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assert.strictEqual(typeof encryption, 'object');
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const encryptedParts = filePath.split('/').map(function (part) {
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let hmac = crypto.createHmac('sha256', Buffer.from(encryption.filenameHmacKey, 'hex'));
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const iv = hmac.update(part).digest().slice(0, 16); // iv has to be deterministic, for our sync (copy) logic to work
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const cipher = crypto.createCipheriv('aes-256-cbc', Buffer.from(encryption.filenameKey, 'hex'), iv);
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let crypt = cipher.update(part);
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crypt = Buffer.concat([ iv, crypt, cipher.final() ]);
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return crypt.toString('base64') // ensures path is valid
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.replace(/\//g, '-') // replace '/' of base64 since it conflicts with path separator
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.replace(/=/g,''); // strip trailing = padding. this is only needed if we concat base64 strings, which we don't
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});
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return encryptedParts.join('/');
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}
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function decryptFilePath(filePath, encryption) {
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assert.strictEqual(typeof filePath, 'string');
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assert.strictEqual(typeof encryption, 'object');
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const decryptedParts = [];
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for (let part of filePath.split('/')) {
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part = part + Array(part.length % 4).join('='); // add back = padding
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part = part.replace(/-/g, '/'); // replace with '/'
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try {
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const buffer = Buffer.from(part, 'base64');
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const iv = buffer.slice(0, 16);
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let decrypt = crypto.createDecipheriv('aes-256-cbc', Buffer.from(encryption.filenameKey, 'hex'), iv);
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const plainText = decrypt.update(buffer.slice(16));
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const plainTextString = Buffer.concat([ plainText, decrypt.final() ]).toString('utf8');
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const hmac = crypto.createHmac('sha256', Buffer.from(encryption.filenameHmacKey, 'hex'));
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if (!hmac.update(plainTextString).digest().slice(0, 16).equals(iv)) return { error: new BoxError(BoxError.CRYPTO_ERROR, `mac error decrypting part ${part} of path ${filePath}`) };
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decryptedParts.push(plainTextString);
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} catch (error) {
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debug(`Error decrypting part ${part} of path ${filePath}:`, error);
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return { error: new BoxError(BoxError.CRYPTO_ERROR, `Error decrypting part ${part} of path ${filePath}: ${error.message}`) };
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}
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}
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return { result: decryptedParts.join('/') };
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}
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function createReadStream(sourceFile, encryption) {
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assert.strictEqual(typeof sourceFile, 'string');
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assert.strictEqual(typeof encryption, 'object');
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const stream = fs.createReadStream(sourceFile);
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const ps = progressStream({ time: 10000 }); // display a progress every 10 seconds
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stream.on('error', function (error) {
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debug(`createReadStream: read stream error at ${sourceFile}`, error);
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ps.emit('error', new BoxError(BoxError.FS_ERROR, `Error reading ${sourceFile}: ${error.message} ${error.code}`));
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});
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stream.on('open', () => ps.emit('open'));
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if (encryption) {
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let encryptStream = new EncryptStream(encryption);
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encryptStream.on('error', function (error) {
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debug(`createReadStream: encrypt stream error ${sourceFile}`, error);
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ps.emit('error', new BoxError(BoxError.CRYPTO_ERROR, `Encryption error at ${sourceFile}: ${error.message}`));
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});
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return stream.pipe(encryptStream).pipe(ps);
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} else {
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return stream.pipe(ps);
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}
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}
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function createWriteStream(destFile, encryption) {
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assert.strictEqual(typeof destFile, 'string');
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assert.strictEqual(typeof encryption, 'object');
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const stream = fs.createWriteStream(destFile);
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const ps = progressStream({ time: 10000 }); // display a progress every 10 seconds
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stream.on('error', function (error) {
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debug(`createWriteStream: write stream error ${destFile}`, error);
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ps.emit('error', new BoxError(BoxError.FS_ERROR, `Write error ${destFile}: ${error.message}`));
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});
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stream.on('finish', function () {
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debug('createWriteStream: done.');
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// we use a separate event because ps is a through2 stream which emits 'finish' event indicating end of inStream and not write
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ps.emit('done');
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});
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if (encryption) {
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let decrypt = new DecryptStream(encryption);
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decrypt.on('error', function (error) {
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debug(`createWriteStream: decrypt stream error ${destFile}`, error);
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ps.emit('error', new BoxError(BoxError.CRYPTO_ERROR, `Decryption error at ${destFile}: ${error.message}`));
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});
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ps.pipe(decrypt).pipe(stream);
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} else {
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ps.pipe(stream);
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}
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return ps;
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}
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