S: Good morning, Kris, please excuse me. You are using WhatsApp, I presume.
If so, how are you dealing with the problem of WhatsApp uploading the address book? Ignore it? Change config? Edit address book contacts?
Why I am asking: by not using WhatsApp, I am more and more out of the loop (school, parents, sport clubs, etc). At the moment I am trying to resist, proably being the last person on Planet Earth doing that.
Kris: Just use it. ‘Complete upload of the address book’ is untrue, and uninformed bullshit, btw. WhatsApp hashes stuff, and uploads the hashes. Hashes equal -> match.”
Out-of-network numbers are stored as one-way, irreversibly hashed values. WhatsApp uses a multi-step treatment of the numbers, with the key step being an “MD5” hash function. The phone number and a fixed salt value serve as input to the hash function, and the output is truncated to 53 bits and combined with the country code for the number. The result is a 64-bit value which is stored in data tables on WhatsApp’s servers.
The findings complain about that, because it is not perfect, but I personally believe that to be a pretty good compromise, making you discoverable without pasting the actual numbers all over the place.
S: Thanks, didn’t know that. Problem solved.