Keysign

How Vultisig keysigning works. Multi-device threshold signing process for Fast Vaults and Secure Vaults. QR pairing, verification, and broadcast.

Keysigning is the process by which threshold devices collaborate to sign a transaction. This page explains how signing works for both Fast Vaults and Secure Vaults.

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How It Works

Transaction signing flowchart

Session Initiation

A device initiates a cryptographic session to sign a transaction. It transforms user input into the transaction payload while acting as the session host. The initiating device sends session metadata (including session ID) to the Vultisig relay server or broadcasts it over the local network. A QR code is generated containing session-specific details for pairing devices.

Device Pairing

Pairing devices scan the QR code to join the session using the embedded session ID and encrypted hex chain code. The initiating device monitors joining devices and initiates the keysigning ceremony when the required threshold is reached.

Signing Ceremony

During the keysigning ceremony, participating devices jointly sign the transaction using threshold signature cryptography. No single device ever has access to the complete private key—only the final signature is assembled.

Broadcast

Upon successful completion, the initiating device propagates the signed transaction to the blockchain and distributes the transaction hash to other participating devices for verification.

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Fast Vault Signing

Fast Vaults provide a single-device signing experience with the Vultiserver as the automatic co-signer.

Steps

1. Prepare the transaction (Send or Swap)

2. Tap Continue or Swap

Send screen

Swap screen

1. Verify transaction details

Send verification

Swap verification

1. Enter your password

2. Wait for signing to complete

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Secure Vault Signing

Secure Vaults require threshold devices to physically participate in signing.

Video Guide

Preparation

Depending on your vault configuration (2-of-2, 2-of-3, 3-of-4, or m-of-n), have the threshold number of devices ready.

One device creates the transaction, other devices verify and co-sign. Both devices will co-sign but only one transaction is sent—no duplicates.

On the Main Device

1. Prepare the transaction (Send, Swap, or DeFi action)

2. Tap Continue or Swap

Send screen

Swap screen

1. Verify all details on the confirmation screen

2. Check reminder boxes and tap Sign

1. A QR code will appear

Select Local mode to sign without using the Vultisig relay server (requires same WiFi network).

On the Pair Device(s)

1. Select the same vault

2. Tap the Camera icon

3. Scan the QR code from the main device

1. Verify transaction details match

2. Tap Join key sign

Completion

Signing starts automatically when the threshold of devices has joined. The transaction signs and broadcasts from one of the devices.

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Network Modes

Mode	Description	Use Case
Internet	Via Vultisig relay server	Devices on different networks
Local	Via local WiFi (mDNS)	Same network, maximum privacy

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Related

• TSS Actions — Key generation, signing, resharing

• Sending — How to send transactions

• Swapping — How to swap assets