Signal is exploring a new registration method that could allow users to create accounts without providing a phone number. This approach leverages zero-knowledge proofs (ZKP), a cryptographic technique already used by Signal for features like donation badges and group membership verification. ZKPs enable verification without revealing specific details, which helps maintain user privacy.
The Signal client is designed to minimize trust in the server, and the use of ZKP aligns with this philosophy by allowing verification of information such as username validity without exposing the actual data. However, questions remain about how completely phone numbers can be unlinked from usernames and what data might persist locally or on servers.
There are concerns about the potential for abuse if phone numbers are removed from the registration process. For example, spammers might exploit the system by repeatedly unlinking numbers to create multiple accounts. To mitigate this, Signal could implement cooldown periods between registrations, though the optimal duration is still uncertain.
If implemented, Signal plans to provide more technical details to clarify privacy implications. This development reflects ongoing efforts to balance user anonymity with security and abuse prevention in messaging platforms.