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# System prepended metadata

title: Sign In with Bitcoin

---

# Sign In with Bitcoin

## Roles

Requester: Creates challenge (request) and sends it to Verifier.
Verifier: Has trusted UX with user. (iOS device)
Controller: Has control of private key material. (ring)

## Workflow

1. Requester creates challenge and sends it to Verifier in form of QR code.
2. Verifier uses Controller, which controls the private key of an existing UTXO, to sign challenge.
3. Requester verifies signature on challenge and existence of UTXO.

