Ecosystem

Anyone can build on Velum: exchanges, wallets, hardware wallets, custodians, staking and explorers. We keep the protocol and a reference implementation open. Only the messaging app is closed.

What is open {#abierto}

You don't need to ask our permission. We only ask that you don't use the Velum brand in a way that looks like one of our products.

Exchanges {#exchanges}

• Your own node. Install velum-node and let it sync; don't rely on the public gateway. Local RPC at ws://127.0.0.1:7420/ws?role=client, not exposed to the internet. Check that chain.block {height: 0} returns header.chain == "{{chain}}".
• Units. VEL has 6 decimals; every amount on the chain is an integer in µVEL.
• Confirmations. There is no instant finality yet: 30 blocks for normal amounts and one epoch for large amounts. Store the hash of every credited block and, if it changes, read again.
• Deposits. One address with a per-customer memo, or one address per customer at m/44'/7420'/0'/0'/i'. The SDK's DepositWatcher walks blocks with N confirmations; a deposit's unique key is its txId.
• Withdrawals. The SDK's buildTransfer. Below the threshold, zero fee with a work stamp; above it, 1 basis point. Sign offline with signTxBody on the cold machine.
• Hot and cold. The hot wallet holds what is withdrawn in a day; the cold wallet, offline, tops it up.

Technical detail in Wallets and exchanges.

Wallets {#carteras}

• 24-word BIP-39 phrase. Wallet = SLIP-10 ed25519 at m/44'/7420'/account'/0'/index'. The official app uses 0'/0'/0'.
• The messaging identity and device keys come from the same phrase via HKDF and are not wallet keys.
• Always show the amount, the exact fee (usually 0) and what the recipient gets.

Hardware wallets: Trezor and Ledger {#hardware}

• The pow work stamp is part of what is signed: the computer calculates it before sending the transaction to the device.
• The device must show the full destination, the amount with its token, the fee and the memo, and warn if chain isn't {{chain}}.
• There is a proposed Ledger app (APDUs GET_PUBLIC_KEY and SIGN_TX) in the ecosystem specification.

@velum/sdk {#sdk-abierto}

import { walletFromPhrase, buildTransfer, VelumRpc, DepositWatcher } from "@velum/sdk";

• walletFromPhrase(phrase, account, index): SLIP-10 wallet.
• buildTransfer, buildDelegate, buildUndelegate, signTxBody: build and sign, including offline.
• VelumRpc: client for the node RPC.
• DepositWatcher: deposits with N confirmations.

Examples: deposit-watcher.ts, withdrawal-signer.ts and staking.ts.

Delegated staking {#staking}

• stake.delegate { node, amount }: your VEL is locked on the chain and raises the node's weight in the bridge lottery, with the same cap as the node's own bond.
• stake.undelegate { node, amount }: it returns to your account after 14 days.
• node.commission { bp }: each node sets its commission between 0 and 20%. At most one change every 7 days, of ±5 points.
• Each epoch, what the node discovers is divided: its commission, and the rest pro rata between its own bond and its delegators. No more is ever divided than there is.
• There is no guaranteed return. If the node doesn't work, it discovers nothing.

Custodians

Holding keys for third parties is a regulated service (a crypto-asset service provider in the EU). Keep one wallet per customer, or an internal ledger reconciled with the chain every day.