A transfer, step by step

Sending value across a bridge takes a few steps. The order surprises people: the first step happens on the chain you are sending to.

1. Get a ticket. On the destination chain, you create a claim ID. Think of it as a numbered coat-check ticket. It stands for one transfer.
2. Hand over the coat. On the source chain, you commit the assets and quote the ticket number. The assets are locked, or burned if they were wrapped copies going home.
3. Witnesses confirm. Witness servers see the commit. Each one signs a statement and posts it on the destination chain.
4. Release. When enough witnesses agree, the funds are released on the destination chain.
5. Witnesses get paid. A small reward, set by the bridge, is split among the witnesses that signed.

If you named a destination account in step 2, the funds arrive there automatically. If you did not, you claim them yourself with the ticket.

The ticket number matters. The reference page for the commit transaction is blunt: quote a wrong number and the funds are lost. Check the number in a validated ledger before you commit.

You need an account on the destination chain to get a ticket. For a first visit, XRP bridges can offer a separate step that creates a new account on the far side.

Transfer flow.

Details:

• XChainCreateClaimID includes SignatureReward. It must match the value on the Bridge entry.
• XChainCommit must come from the account named as OtherChainSource.
• XChainCommit has an optional OtherChainDestination. With it, funds transfer when quorum is reached.
• xrpl.org notes that some cases still need a claim, such as a destination with Deposit Authorization enabled.
• XChainClaim is sent by the claim ID's owner. It can pay any Destination that exists. A failed claim keeps the claim ID, so it can be retried with other parameters.
• A successful transfer destroys the XChainOwnedClaimID. That prevents replay.

Attestations. Any account can submit one. The signature must come from a key on the door account's signer list. If the signer list changes before quorum, the new list applies and some collected signatures may be dropped. A quorum must also agree on the reward amount, so one witness cannot inflate it.

Account creation. XChainAccountCreateCommit works only on XRP-XRP bridges.

• Amount must be at least the bridge's MinAccountCreateAmount.
• Witnesses attest with XChainAddAccountCreateAttestation. The ledger tracks them in an XChainOwnedCreateAccountClaimID.
• At quorum the new account is funded automatically.
• If attestations never arrive, account creation is blocked until they do. A bridge disables this transaction by leaving MinAccountCreateAmount unset.

An open XChainOwnedClaimID blocks deletion of the account that owns it. Finish the transfer first.

Related: Locking and issuing.