aniltan / kinderchat

Secure Texting for Children

KinderChat

The goal of this application is to provide a secure chat application for children, where all the communications between children are encrypted and yet, parents have a golden key to monitor the communications of their children.

This application is born out two simple principles - first, that if a child has nothing to hide, he has nothing to fear; and second that a parent must trust but verify.

By allowing parents to monitor the conversation of their children with third parties, we can ensure their safety and a more harmonious future for everyone.

Cryptography and Onboarding Experience

At the core of Kinder Chat lives a secure cryptographic system. It is as secure as we could design it. Still, it could probably be improved by security and cryptographic experts. We welcome your input.

We have tried to solve the problem of onboarding users while providing a secure communication system.

Each time you run an instance of Kinder Chat, a new private/public key pair is generated. The private key never leaves your device. It is never posted to the web and is never recorded on the Kinder Chat servers. Instead, the public key is sent to the servers, and users are then able to merge one or more endpoints into a single identity.

For example, the identity "Miguel de Icaza" associated with the phone [phone] and the email address [email protected] would have many public keys associated with it, one for each device that completes the verification process.

Consider this scenario: Jose and Maria are the parents of Jesus, and Magdalena is a close friends of his.

When Magdalena wants to send a message to Jesus, her Kinder Chat application will retrieve from the server all the keys that are associated with Jesus. That will for example include the Jesus' iPhone key, and the Jesus' Android key, and also the keys for the Jesus' parents, Maria and Jose.

So if Maria sends the message "Sup yo", KinderChat encrypts that message using four different keys, one for each recipient (two of them are Jesus' different devices, and one for each parent in this case). Then the messages are posted to the server and stored in the respective buckets. Then the client KinderChat apps for Jesus, Maria and Jose will retrieve those copies and decrypt the results on each device.

This has some important side effects: if you change devices, or delete and reinstall the application on a device, new keys will be generated. This means that you could never decipher any previous messages stored. Your device becomes your key.

Kinder Points

To ensure that kids use the application for all their communication, a system of points was introduced. Points are earned for using the application, eating their veggies, or completing chores.

In-App purchases [*] allow children to purchase Kinder Points from their allowance. This empowers children to increase their Kinder Point scores on weeks where they have not performed their chores, ate their veggies or used the application enough. This teaches kids a valuable civics lesson: everything is for sale for the right price.

[*] This feature is not yet available in this public release.

Platforms

The code contains clients for Android, iOS and Windows 10. It contains a watchOS app for parents to grant points.

The Matriarch app is a Windows desktop application dashboard that centralizes the management and statistics for the activities performed by their offspring.

User Experience

The individual clients are written using native code for Android, iOS and Windows. They should provide a good blueprint for how to build native user experiences while sharing code across all three platforms.

Backend

We are hoping that no child will be left behind; that is, we want every kid in the world to use this safe and secure system, so we have designed the backend to scale.

The backend is built on top of Azure, and uses several Azure services to scale up. It uses the ServiceBus to connect the frontends to the backing stores.

This diagram shows the high-level architecture:

Presentation

KinderChat is an application that we presented at Microsoft Build 2015 in April of 2015.

We introduced Kinder Chat at Build 2015, you can watch the video and download the slides for this project here:

https://channel9.msdn.com/Events/Build/2015/3-770

You can fast-forward to 8:50 to watch the introduction of Kinder Chat.

Slides or View online

Status

We build this code for about a month before the Build conference took place, and had not really had the time to work on this since then. While we like the user experience that we got up to the time of the release, the design language and idioms have evolved from April. If we had time, we would likely refresh some elements.

There is also a lot of room for improvement on the backend and how to scale it, but we have not really touched the code since the conference.

This project was originally conceived under a different name and a different target audience. Our delay to release the code was due to project cleanup. We may release the original project at a future date.