Heartnotes

Personal diary app - cross-platform, offline, encrypted.

Features:

OS X desktop app (Windows + Linux coming soon)
Completely offline, password is not stored anywhere
Rock-solid encryption (AES-256-GCM)
Auto-save diary as you type
Timeline view for easy access to past entries
Export diary to readable HTML file at any time

Fetch the latest release from http://heartnot.es.

## Technology

Built using React.js + Flummox + Electron.js.

Encryption details

This uses the SJCL library for AES-256 encryption as well as for the PRNG algorithm to generate random seed data and salts.

A new encryption key is derived from the user's password as follows:

Use Fortuna PRNG with multiple event inputs (mouse, keyboard, accelerometer etc) to generate a salt.
Use salt and password as inputs to PBKDF2-SHA512 to generate a 512-bit key. (The number of iterations of PBKDF2 is set such that generation takes 1 second on the user's machine- on a Macbook Air 2012 this easily results in >10000 iterations.
Use the first 256 bits of the key with AES-256-GCM + random IV to encrypt data and store it in the diary file.
Store the input salt and PBKDF2 iteration count in the user's diary file.

The next time the user enters the right password, we use the stored salt and iteration count to regenerate the right key for decryption.

Development

Node.js 0.12+ required.

Setup:

$ npm install -g electron-prebuilt@0.33.4
$ npm install

Run dev server (http://localhost:3000):

$ gulp

NOTE: Add --minified on the command-line to enable JS and CSS minification during build.

Production build

$ npm run release

You will find the Heartnotes.app OS X executable in build-electron/relese/...

Release checklist

Make final commits
Update version in package.json
Commit version update and push
Tag commit as
Push tag
Do a production build (see above)
Create release entry on Github and attach built executable
Announce to world!

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.