Block Confirmation and Transaction Finality

When you submit a transaction to CPN, it is initially in the pending state and waiting to be broadcast to the blockchain. Once the transaction is broadcast to the blockchain, it transitions to the broadcasted state, and the transaction is waiting to be included in a block.

CPN monitors each block of supported blockchains and the status of CPN transactions on those chains, updating the status as necessary.

Block confirmation

Block confirmation is the process of validating and adding transactions to a block on a blockchain. Each time a new block is added to a blockchain, it confirms the previous blocks.

Without a sufficient number of confirmations, transactions are vulnerable to alteration through blockchain reorganization. Blockchain reorganization occurs when validators discard one or more blocks that were previously part of the canonical chain and replace them with a different set of blocks, rewriting part of the chain.

Note: Blockchain reorganizations can happen for a variety of reasons. It’s an engineering best practice to expect reorganizations and make your system resilient to them.

Each additional block confirmation added after a block makes that block less likely to be removed in a reorganization. Each block confirmation adds confidence that the transaction is permanently included in the blockchain.

Confirmation number

For a given block, the confirmation number is the number of subsequent blocks added to the blockchain.

For a given transaction included in a block, CPN waits for a set number of blocks (in addition to the original) to be added to the chain before it considers the transaction final. This number varies across supported blockchains. When a sufficient number of blocks are appended after the original block, CPN updates the status of the transaction to completed and notifies both the OFI and BFI of the status change.

Note: Even if a transaction is visible on a block explorer, it doesn’t necessarily mean that the transaction is considered completed by CPN, because it’s possible that it hasn’t reached the number of block confirmations for finality.

Reorganization risk

Although Circle may broadcast transactions initiated through CPN to the blockchain network, Circle cannot guarantee that the transaction is recorded or permanently confirmed by the network. Transactions over CPN may be dependent on underlying blockchain networks that Circle does not control, and CPN Participants assume all risks associated with the blockchain network operations and any operating changes, including in the unlikely event of a deep reorganization or other invalidation of previously confirmed transactions.

Circle shall not be liable for any loss or damage arising from issues with, or any delays, reversals, or failures of transactions caused by such operations and operating changes.