Signal is rolling out Signal Login in its Android 8.28 beta, a feature that for the first time allows users to register for the app without a phone number.
On the one hand, this is a major development because it removes the biggest roadblock to wider adoption of the privacy-minded messenger, and that is its very own core dependency on phone numbers. On the other, there are several caveats.
More: Signal's Phone Number Problem Finally Has an Asterisk
The phone number has always been Signal’s weakest link, privacy-wise, because it is the link to a real-world identity, that of a telecom subscriber, and also to a physical SIM card that can be swapped by an attacker. But now Signal says that the Account ID and Recovery key replace the phone number.
This is how Signal describes Signal Login: “an optional registration method that allows users to create a Signal account without providing a phone number.”
And this is how the nonprofit explains the payment: “The price at launch is $2.99 / €3.49 (EUR price includes VAT), although this may vary by region and currency.” The payment is a one-time payment, and Signal promises that it uses “the same zero-knowledge proofs as Signal’s donation system, meaning there is no direct link between your payment and your Signal account.”
The Account ID and Recovery key are the only two pieces of information that can be used to access the account, Signal said, adding, “When you purchase a Signal Login, you’ll be given an Account ID and a Recovery key. This is also the Recovery key used for on-device backups and Signal Secure Backups, even if you enable backups at a later time.”
The key is sensitive information, and Signal advises users to “save your Account ID and Recovery key in a password manager.”
If both are lost, the account is gone – it cannot be recovered. This is different from the current system, where a phone number can be used to recover an account. Two-factor authentication is available for accounts created with Signal Login, as TOTP-based 2FA.
The optional username, which was rolled out recently, can also be used with this type of account, and without it, nobody can start a chat with you – you can either start the chat, or join a group using a group link. Devices linked to an account created with Signal Login work the same as those linked to a phone-number account.
For now, Signal Login is available only to those creating new accounts, and only on Android, with iOS to follow later. It also requires Play Services on Android because the only payment method currently accepted is Play Store’s in-app payment. As AboutSignal, which reported the rollout, put it, “It’s currently not yet possible to buy a Signal Login account on a device that has no Play Services.”
Signal, the site noted, says “they have plans to add more payment methods, but currently only offer Play Store in-app payments, which requires Play Services.”
“Signal Login currently only works for new accounts,” the nonprofit said.
It is unclear at this time whether de-Googled devices that have Play Services sandboxed, such as those running GrapheneOS, or those using the microG implementation of Google’s API that doesn’t require Play Services, can be used to buy Signal Login.
The ability to remove a phone number from an existing account may come later.
