⛓️ Blockchain & Web3 · Network

Hot and Cold Wallet Custody

How a custodian separates internet-connected hot wallets from offline cold storage, with signing hardware and an air-gapped transfer process.

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Drawing diagram…

What this diagram shows

Only a small float sits in the online hot wallet
Cold keys never touch a networked machine
Refills from cold storage need several people

Prompt used

Network view of crypto custody: the wallet service in a private subnet talks to blockchain nodes and to HSMs holding hot wallet keys. The cold storage room is air-gapped: offline signing machines with hardware wallets, and transactions move in and out by QR code. A multi-signature policy needs 3 of 5 key holders for cold transfers.

Mermaid code

flowchart LR
  INT((Internet)) --- FW[Firewall]
  FW --- NODES[Blockchain Nodes]
  subgraph PRIV[Private Subnet]
    WS[Wallet Service]
    HSM[HSM - hot keys]
  end
  NODES --- WS
  WS --- HSM
  subgraph VAULT[Air-gapped Cold Room]
    OS1[Offline Signer 1]
    OS2[Offline Signer 2]
    HW[Hardware Wallets]
  end
  WS -.QR code transfer.- OS1
  OS1 --- HW
  OS2 --- HW
  KH[Key Holders - 3 of 5] --- VAULT

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