Greta is a lightweight yet powerful notes application built for Android which supports encryption and with a focus on security. It is completely free as in freedom, free of charge, and free of trackers or ads, forever.
- Notes are stored only locally, the app does not access the Internet at any time.
- Material Design UI, dark mode by default. Simple but intuitive menus.
- Create/View/Modify/Delete functionalities are clear and represented by icons, long-clicking on a note displays a larger menu.
- Easy and secure encryption and decryption of notes:
- Different passwords for each note.
- After editing a previously encrypted note, it is re-encrypted automatically.
- Encryption keys are securely generated from users' passwords:
- Passwords or keys are never stored in your phone, either temporarily or permanently.
- A different salt is generated for each encrypted note.
- Notes can be encrypted/decrypted from the main screen by clicking on meaningful icons.
- Technical details about encryption:
- AES-128 bit keys.
- CBC encryption mode, PKCS5 padding.
- HMAC for integrity checking, hash function used is SHA256.
- Notes can be marked as favourite, highlighted in color.
- Export and Import of notes is supported:
- Notes (encrypted or not) and preferences (favourites) can be easily exported into a JSON file.
- Notes can be imported by selecting the corresponding JSON file. Warning: Currently overwrites the previous notes if any.
- Notes can be ordered on screen according to different methods:
- By date, descending.
- By date, ascending.
- Favourites first, then by date descending.
- Favourites last, then by date ascending.
- Includes Settings menu for easy access to different app options.
- Licenses for third party libraries are clearly shown in About menu.
The full Kanban board will be publicly released once I clean it up. As a summary, Greta still needs to:
- Refactoring is needed. Some fragments have too many responsibilities.
- Include more
bugsfunctionalities, similarly to other notes apps:- Support tags for notes, and filtering by tag.
- Include a deleted/archived notes menu.
- Support notes with different colors.
- Etc...
- Unit tests / espresso tests needed.
Greta has been created as a side project with the purpose of practicing my Android, Databases and Cryptography skills, and of course for fun. I am still (self-)learning Android development, so please bear in mind that optimality and good design models are conspicuous by their absence.
Note that, although it has been released to the public and I am actively maintaining it, this app is of personal use and offered AS-IS I am not responsible for harm of any nature derived from its use.
In the future, Greta will be integrated into a larger, more ambitious project which I will eventually release as well.
This project is released under the GPL v3 license. See LICENSE.