Aliases, links and invitations
Velum has no phone numbers or email. There are three ways for someone to find you: an alias, a link with your card or a QR code. And to message someone who doesn't have the app yet, an invitation.
Aliases
An alias is a unique, public name, like @lucia, that points to your contact card.
name.register { name, card }
| Rule | Value |
|---|---|
| Characters | 3 to 24, only a-z, 0-9, _ and . |
| Per wallet | One |
| Duration | One year; renewable |
| Cost | A large proof of work (about 5 seconds), to discourage squatting |
The card (card) contains your identity public key, a first-contact prekey (X25519 + ML-KEM-768) and a request mailbox. It's public and pseudonymous: it doesn't say who you are.
Contact links
| Link | Purpose |
|---|---|
https://velum.consultorabim.com/@alias |
Contact by alias |
https://velum.consultorabim.com/c/<card> |
The card travels inside the link; works without an alias |
On a phone, these links open the app directly (Universal Links on iOS, App Links on Android). If the app isn't installed, the website explains how to install it.
First contact
- Whoever wants to talk to you sends a
contact.requestsealed to your card's prekey. - You accept it or ignore it.
- If you accept, you swap device lists and from then on everything works as described in Cryptography.
Invitations for people without the app
You can message someone before they install Velum:
- Your app creates a single-use invitation with fresh keys.
- It encrypts your pending messages for that invitation and leaves them in a mailbox derived from it for 24 hours.
- You send the link by SMS, email or another app.
- If the person installs Velum and opens the link within 24 hours, they get the messages. If not, they are destroyed.
What about phone numbers?
Velum never publishes phone numbers, not even hashed: phone number hashes can be guessed by trying every number. You can invite someone from your address book by link. Sign-up with an SMS-verified phone number is an open decision: it would need a paid SMS provider and a central point.
Linking your computer
Besides the normal mode (the active phone shows the rotating QR code and the new device reads it), there is reverse linking: the new device shows the QR code and the active phone scans it, like WhatsApp Web. The desktop app uses it, since computers usually have no camera.