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Executive summary

Cold vaults isolate the signing environment from network-connected systems.

  • Cold vault signing uses the same governance approval model as hot vault signing.
  • The difference is transport: operations move between the online system and the cold vault server as .dat files.
  • A cold bridge runs on the cold vault server and provides the local interface that the vault polls for signing work.
  • Accounts and manifests created for a cold vault remain Pending, and transactions remain Prepared, until you import the signed payload back into Ripple Custody.
  • Cold vault operations give up speed and automation in exchange for stronger physical isolation.
Why this matters

Cold storage reduces the attack surface for high-value assets because the online deployment cannot reach the signing environment. Even if an attacker compromises an online component, they still cannot directly reach the cold vault signing environment.

For architects and operators: Cold vaults require operational discipline. You need a cold vault server, controlled transfer media, clear verification steps before signing, and recovery procedures for the server, vault configuration, and KMS material.

Prerequisites

Before using cold vaults, you should understand:

Cold vault architecture

A cold vault uses a physically isolated signing environment. The online deployment prepares operation payloads, an operator transfers those payloads to the cold vault server, the cold bridge makes the payload available to the local vault, and the operator transfers the signed result back for import.

Cold vault server

Manual transfer

Online Ripple Custody environment

UI or API

Core services

Unsigned .dat file

Signed .dat file

Cold bridge

Vault

KMS
HSM or MPC

Cold vault server

Manual transfer

Online Ripple Custody environment

UI or API

Core services

Unsigned .dat file

Signed .dat file

Cold bridge

Vault

KMS
HSM or MPC

ComponentRole
Online Ripple Custody environmentCreates accounts, transactions, and manifests as governed operations. Exports pending cold vault operations.
Transfer mediaMoves .dat payloads between the online environment and the cold vault server.
Cold bridgeRuns on the cold vault server. Provides the local UI and API used to upload, inspect, sign, and download operation payloads.
VaultPolls the cold bridge for signing work, verifies the notary attestation, builds the transaction, and signs.
KMSProtects the signing key material and performs cryptographic operations.

Hot vaults and cold vaults

Both vault types follow the same governance and approval process. They differ after Ripple Custody prepares the operation for vault signing.

FactorHot vaultCold vault
ConnectivityNetwork-connected.Air-gapped.
Signing pathVault polls the online API for operation queries.Vault polls the local cold bridge for operation queries.
Operator involvementAutomated after approval.Manual export, transfer, signing, and import.
Typical useFrequent transactions, payments, and operational liquidity.High-value reserves and cold storage.

Signing workflow

VaultCold bridgeTransfer mediaOnline systemUserVaultCold bridgeTransfer mediaOnline systemUserSubmit and approve operationPrepare cold vault operationExport unsigned .dat fileTransfer to cold vault serverVault polls for signing workVerify notary attestation and signReturn signed payloadDownload signed .dat fileImport signed operationsContinue account, transaction, or manifest processing
VaultCold bridgeTransfer mediaOnline systemUserVaultCold bridgeTransfer mediaOnline systemUserSubmit and approve operationPrepare cold vault operationExport unsigned .dat fileTransfer to cold vault serverVault polls for signing workVerify notary attestation and signReturn signed payloadDownload signed .dat fileImport signed operationsContinue account, transaction, or manifest processing

First-time cold vault handshake

When you first register a cold vault, it can appear in a Pending state because it cannot automatically connect to the online deployment. Complete the manual handshake before using the vault for accounts, transactions, or manifests.

At a high level:

  1. On the cold vault server, retrieve the vault UUID and vault public key from the vault container logs.
  2. Register the cold vault using the standard vault registration flow, with the UUID and public key from the logs.
  3. Download the vault data from the cold bridge on the cold vault server.
  4. Transfer the .dat file to the online environment.
  5. Import the file into Ripple Custody.
  6. Verify that the vault status is Completed.

For steps, see Process cold vault operations in the UI or Process cold vault operations with the API.

Operational responsibilities

ResponsibilityWhy it matters
Air-gap controlsThe cold vault server must remain isolated from networks so no one can reach signing remotely.
Transfer media controls.dat files move between the online environment and the cold vault server. Use approved media and handling procedures.
Payload verificationInspect operation details before you allow the cold vault to sign.
HSM master keyAfter you register the vault, the cold vault server stores no state locally. To recover a cold vault, the replacement HSM must use the same master key as the original HSM.
Configuration backupRecovery requires the same vault configuration, including the vault UUID and the notary messaging public key.

Next steps

TaskPage
Plan the cold vault serverCold vault server planning
Deploy the cold bridgeDeploy a cold bridge
Register, view, update, lock, or unlock vaultsManage vaults
Process cold vault operations in the UIProcess cold vault operations in the UI
Process cold vault operations with the APIProcess cold vault operations with the API
Recover cold vault operations after server lossRecover a cold vault