Vitalik Backs Signal's Phone-Free Registration, Calls for Per-Message Unlinkability

Ethereum co-founder Vitalik Buterin has welcomed Signal's recently announced exploration of letting users register accounts without a phone number. In his post, Buterin said the move would help reduce dependence on phone numbers, which he described as a highly oligopolistic system, lower the identity security risks associated with SIM swaps, and make it harder for governments to pressure Signal to block users based on nationality. He nonetheless cautioned that the change, while better than the status quo on privacy, only provides confidentiality, not genuine anonymity. Metadata including message timing, frequency, and recipient details can still be used to piece together a user's identity. Buterin argued that as artificial intelligence advances, long-term persistent anonymous accounts are becoming obsolete. The only defensible form of privacy, he contends, is 'per-message unlinkability' – meaning no one other than the sender and recipient knows who is communicating. He noted that newer communication tools such as Session and SimpleX, along with coin-mixing networks, are already exploring this approach. He also added that defending against spam and denial-of-service attacks will be a key focus going forward.