• 4 Posts
  • 24 Comments
Joined 1 year ago
cake
Cake day: November 18th, 2023

help-circle


















  • At least the private contact discovery is not very private:

    The client calculates the truncated SHA256 hash of each phone number in the device’s address book.
    The client transmits those truncated hashes to the service.

    Phone numbers are so not-sparse that there even was a game to text your “number neighbor”. I can probably build a pretty effective rainbow table for this with my current hardware.


  • WhatsApp started is an XMPP client, but they use lots of proprietary extensions (doesn’t matter since they don’t federate). You can build very robust and scalable messengers with it if you want to.

    The open source implementations are developed by like 1-2 guys in their spare time and they’re not far behind (and sometimes even ahead) other federated messengers which received tens of millions in venture capital funding.