LmCast :: Stay tuned in

Registration without a phone number on Signal will use zero-knowledge proofs

Recorded: Sept. 14, 2026, 12:10 a.m.

Original Summarized

Registration without a phone number - Page 10 - Feature Requests - Signal Community

Signal Community

Registration without a phone number

Feature Requests

rassilon1963

(Talya (she/her))

August 22, 2026, 6:49pm

200

you have legitimate concerns, but you’re very wrong about this. zero-knowledge proofs are not only the technology behind donation badges and backup payments, but also behind groups. they can’t tie you to a specific donation just like they can’t tie you to a specific group.

kevino:

Not to forget, signal could always be subpeaned to keep metadata information relating to certain accounts.

the great thing about Signal is the client is designed to already not trust the server. in fact you can show that Signal is perfectly safe without even looking at server code.

Avitus

(Encrypt your life)

August 26, 2026, 9:29pm

201

github.com/signalapp/Signal-Android

Add signal login screen scaffolding.

committed 04:14PM - 25 Aug 26 UTC

greyson-signal

+998
-2

alex-signal

(Alex Hart)

August 26, 2026, 11:45pm

202

ZKP is also used for verifying things like username character set and length without actually revealing contents which is super cool and comprises of math waaaayyyyy above my head.

chiwaijm

(Jeffrey)

August 27, 2026, 12:34am

203

Android Beta feedback for the upcoming Android 8.25 release

github.com/signalapp/Signal-Android

Allow setting username in registration module.

committed 02:57PM - 25 Aug 26 UTC

greyson-signal

+1073
-144

Aku-Stable

August 27, 2026, 2:20am

204

rassilon1963:

zero-knowledge proofs

alex-signal:

ZKP

I was wondering what ZKP was

desert_nip

August 27, 2026, 12:35pm

205

github.com/signalapp/Signal-Android

Add new signal login strings.

committed 07:40PM - 26 Aug 26 UTC

mtang-signal

+1632
-0

Also adjacent. The “save as pdf” is quite interesting. :)

chiwaijm

(Jeffrey)

September 2, 2026, 8:56pm

206

Android Beta feedback for the upcoming Android 8.26 release

github.com/signalapp/Signal-Android

Add basic ability to register numberless account.

committed 07:11PM - 02 Sep 26 UTC

greyson-signal

+871
-359

github.com/signalapp/Signal-Android

Hide some settings for numberless accounts.

committed 07:11PM - 02 Sep 26 UTC

greyson-signal

+87
-62

github.com/signalapp/Signal-Android

Use new zkgroup credential for numberless accounts.

committed 07:11PM - 02 Sep 26 UTC

greyson-signal

+16
-4

github.com/signalapp/Signal-Android

Don't show PIN reminder for numberless accounts.

committed 07:11PM - 02 Sep 26 UTC

greyson-signal

+4
-0

github.com/signalapp/Signal-Android

Hide phone number discoverablity setting for numberless accounts.

committed 07:11PM - 02 Sep 26 UTC

greyson-signal

+13
-9

github.com/signalapp/Signal-Android

Add numberless country code for locale remote configs.

committed 07:11PM - 02 Sep 26 UTC

greyson-signal

+55
-23

github.com/signalapp/Signal-Android

Add basic ability to login to an existing numberless account.

committed 07:11PM - 02 Sep 26 UTC

greyson-signal

+2395
-1160

github.com/signalapp/Signal-Android

Add password manager support to numberless login.

committed 07:11PM - 02 Sep 26 UTC

greyson-signal

+191
-40

signalOne

September 3, 2026, 8:06am

207

For those who are already registered with their phone number and would like to “unlink” it without re-registering for the service… is that possible?

zetabeta

September 3, 2026, 11:36am

208

if this feature happens, signal org should clarify some technical details regarding privacy.
is phone number totally unlinked from username?
what remnants remains, locally in a device? in a server?
my guess is that unlinking is not 100% unlinked. which is leads to a second point. should new account without phone number be better idea. unlinking phone number may not be best option.
although unlinking phone number could be free of charge.

signalOne:

For those who are already registered with their phone number and would like to “unlink” it without re-registering for the service… is that possible?

desert_nip

September 3, 2026, 12:48pm

209

I don’t think anything points to this yet.

zetabeta:

although unlinking phone number could be free of charge.

That seems unlikely, because spammers could just get one number, register with that, unlink, repeat, to get infinitely many accounts for free. Unless they add a cooldown or something…

zetabeta

September 3, 2026, 1:14pm

210

cooldown is reasonably in this case. but even with one month cooldown, it may not be enough to prevent spammers and scammers. it cannot be long either.
cooldown alone may not be enough.

desert_nip:

I don’t think anything points to this yet.

zetabeta:

although unlinking phone number could be free of charge.

That seems unlikely, because spammers could just get one number, register with that, unlink, repeat, to get infinitely many accounts for free. Unless they add a cooldown or something…

Avitus

(Encrypt your life)

September 10, 2026, 12:33am

211

github.com/signalapp/Signal-Android

Add ability to pay for a signal login.

committed 08:37PM - 09 Sep 26 UTC

greyson-signal

+2439
-159

chiwaijm

(Jeffrey)

September 10, 2026, 1:15am

212

Android Beta feedback for the upcoming Android 8.27 release

github.com/signalapp/Signal-Android

Fix setting name rendering when there's no phone number.

committed 08:37PM - 09 Sep 26 UTC

greyson-signal

+36
-12

github.com/signalapp/Signal-Android

Update some numberless assets.

committed 08:37PM - 09 Sep 26 UTC

greyson-signal

+828
-437

github.com/signalapp/Signal-Android

Add confirm dialog when skipping username during numberless reg.

committed 08:37PM - 09 Sep 26 UTC

greyson-signal

+105
-4

github.com/signalapp/Signal-Android

Assume phoneNumberDiscoverability=false for numberless accounts.

committed 08:37PM - 09 Sep 26 UTC

greyson-signal

+3
-3

github.com/signalapp/Signal-Android

Allow full CDS refreshes for numberless accounts.

committed 08:37PM - 09 Sep 26 UTC

greyson-signal

+1
-1

github.com/signalapp/Signal-Android

Improve backup onboarding for numberless accounts.

committed 08:37PM - 09 Sep 26 UTC

greyson-signal

+959
-439

github.com/signalapp/Signal-Android

Add end to end tests for numberless registration flows.

committed 08:44PM - 09 Sep 26 UTC

greyson-signal

+619
-3

github.com/signalapp/Signal-Android

Consider numberless unsolvable reglock to be invalid.

committed 08:44PM - 09 Sep 26 UTC

greyson-signal

+11
-52

github.com/signalapp/Signal-Android

Fix crash during multi-device contact sync for numberless accounts.

committed 08:44PM - 09 Sep 26 UTC

greyson-signal

+3
-3

github.com/signalapp/Signal-Android

Fix e164 NPE for numberless accounts during restore.

committed 08:44PM - 09 Sep 26 UTC

greyson-signal

+10
-10

Authentication and account recovery via email

← previous page

Home

Categories

Guidelines

Terms of Service

Privacy Policy

Powered by Discourse, best viewed with JavaScript enabled

The discussion centers around feature requests and technical considerations within the Signal Community, primarily focusing on the implications of registration without a phone number and the underlying technology of zero-knowledge proofs. A key theoretical point introduced is the role of zero-knowledge proofs, which are noted to be the foundation not only for features like donation badges and backup payments but also for group functionalities. Users suggest that zero-knowledge proofs prevent tying a user to specific donations or groups, providing a layer of privacy.

The technical aspects surrounding Signal's security are also touched upon, with comments acknowledging the design philosophy that the client is intended to not trust the server, implying that security can be demonstrated without examining the server code. Furthermore, zero-knowledge proofs are cited as a mechanism for verifying data, such as username character set and length, without revealing the actual contents, highlighting a complex mathematical underpinning of the system.

A major focus of the feedback involves the implementation and management of numberless accounts. Several feature requests were submitted to enhance the experience and security for these accounts. These requests included adding scaffolding for login screens, allowing users to set usernames during registration, and implementing various settings related to phone number discoverability for numberless accounts. Technical updates related to Android development show ongoing work on these features, including adding new login strings, handling country codes for remote configurations, and considerations for backup onboarding processes.

A particularly complex and contentious topic was the possibility of unlinking a phone number from an existing registration without requiring a complete re-registration. This question raised significant privacy concerns regarding data linkage. Discussions suggested that such an unlinking feature might be technically difficult, and concerns were raised by users about the potential for spammers to exploit this mechanism by registering, unlinking, and repeating the process to generate numerous accounts for free, though the likelihood of such abuse was questioned regarding the need for cooldown periods. The discussion ultimately pointed out that unlinking might not be the optimal solution, suggesting that creating new accounts without a number might be a preferable alternative.

To address security and account management for numberless accounts, there were several specific technical considerations raised, such as assuming phone number discoverability is false for these accounts, allowing full credential service refreshes, and fixing crashes related to contact synchronization across multiple devices. Additionally, considerations were made regarding the validity of unsolvable registration locks and ensuring proper error handling during account restoration. One user noted skepticism regarding the feasibility of free unlinking due to potential abuse vectors, emphasizing that safeguards like cooldown periods might be necessary but insufficient against malicious activity.