The third new function, which isn’t enabled by default and which Signal recommends primarily for high-risk customers, permits you to flip off not simply your quantity’s visibility however its discoverability. That means nobody can discover you in Signal until they’ve your username, even when they already know your quantity or have it saved of their tackle e-book. That further safeguard could be vital if you don’t need anybody to have the ability to tie your Signal profile to your telephone quantity, however it would additionally make it considerably more durable for individuals who know you to seek out you on Signal.

The new telephone quantity protections ought to now make it doable to make use of Signal to speak with untrusted folks in ways in which would have beforehand offered severe privateness dangers. A reporter can now put up a Signal username on a social media profile to permit sources to ship encrypted suggestions, as an illustration, with out additionally sharing a quantity that permits strangers to name their cellular phone in the midst of the evening. An activist can discreetly be a part of an organizing group with out broadcasting their private quantity to folks within the group they do not know.

In the previous, utilizing Signal with out exposing a non-public quantity in both of these conditions would have required establishing a brand new Signal quantity on a burner phone—a tough privateness problem for folks in lots of international locations that require identification to purchase a SIM card—or with a service like Google Voice. Now you’ll be able to merely set a username as a substitute, which will be modified or deleted at any time. (Any conversations you’ve got began with the outdated username will change over to the brand new one.) To keep away from storing even these usernames, Signal can be utilizing a cryptographic perform referred to as a Ristretto hash, which permits it to as a substitute retailer a listing of distinctive strings of characters that encode these handles.

Amid these new options designed to calibrate precisely who can study your telephone quantity, nonetheless, one key function for that quantity hasn’t modified: There’s nonetheless no strategy to keep away from sharing your telephone quantity with Signal itself while you register. The undeniable fact that this requirement persists even after Signal’s improve will little question rankle some critics who’ve pushed Signal’s builders to raised cater to customers looking for extra full anonymity, such that even Signal’s personal employees cannot see a telephone quantity that may establish customers or hand that quantity over to a surveillance company wielding a court docket order.

Whittaker says that, for higher or worse, a telephone quantity stays a vital requisite because the identifier Signal privately collects from its customers. That’s partly as a result of it prevents spammers from creating infinite accounts since telephone numbers are scarce. Phone numbers are additionally what enable anybody to put in Signal and have it instantly populate with contacts from their tackle e-book, a key factor of its usability.

In reality, designing a system that stops spam accounts and imports the consumer’s tackle e-book with out requiring a telephone quantity is “a deceptively hard problem,” says Whittaker. “Spam prevention and actually being able to connect with your social graph on a communications app—those are existential concerns,” she says. “That’s the reason that you still need a phone number to register, because we still need a thing that does that work.”