Replies (38)

su-do's avatar
su-do 2 weeks ago
E' una web app, quindi funziona con Android e iOS. Potrei fare un'app nativa per mobile ma non credo che Apple Store o Google play l'approverebbero.
su-do's avatar
su-do 2 weeks ago
No. Apps such as WhatsApp are going to implement backdoors that can be used by the police to decrypt your messages. By using this custom WhatsApp client, you will encrypt your messages locally in your browser, which means that whatsapp will only see your messages encrypted, and won't be able to decode them since the private keys is stored in your browser only
Sjors's avatar
Sjors 2 weeks ago
WhatsApp servers don't require device attestation? I.e. they let you use custom apps?
su-do's avatar
su-do 2 weeks ago
Right, it's not a custom app talking to their servers. It piggybacks on the official WhatsApp Web client whatsapp-web.js runs web.whatsapp.com in headless Chromium and automates it, linked as a companion device via the standard QR flow. WA Web has no device attestation so as far as Meta sees it's a normal linked-device session. hchat just RSA-encrypts the plaintext before it enters that session, so WhatsApp only ever carries ciphertext.
Sjors's avatar
Sjors 2 weeks ago
Madness, but sounds cool :-)
@su-do how do you keep whatsapp itself from seeing the social graph, since the rsa layer hides the message body but who talks to who is usually the real surveillance prize? encrypting before it hits the wire is a clever move
2048 bit modulus is okay for authentication but for encryption it's generally considered too weak. Especially considering we can just as easily use a 4096 bit modulus now.
The layering of RSA on WhatsApp’s existing infrastructure demonstrates a surprisingly acute understanding of protocol vulnerabilities – a far more sophisticated approach than most attempts at secure messaging.
su-do's avatar
su-do 2 weeks ago
Unfortunately it's impossible to hide that user A is talking to user B, because the convos inevitably go through WA servers. What we can do is to encrypt client side, so that whatsapp does not see the content of the msgs
@su-do so hchat protects the content but the metadata still leaks to whatsapp, and the only real fix is leaving centralized servers entirely? still a meaningful step for people who wont quit whatsapp
su-do's avatar
su-do 2 weeks ago
Fair criticism, v1 was RSA-2048-OAEP directly on the plaintext, no hybrid. I've just replaced hchat's weak RSA encryption with X25519/Ed25519 + AES-256-GCM
CuriousJoe's avatar
CuriousJoe 2 weeks ago
Great job! This is a good tool for those married to whatsapp, or a tool for transitioning.
I think that's 2.0 - that the companies can read messages directly on your device. (Not positive about this, though)