Understanding the Bitcoin Transaction Verification Process
Bitcoin transactions are verified through a multi-step process that ensures the integrity and security of the network. In this article, we will look at the specific verifications performed on a new Bitcoin transaction (TX) and the order in which they occur.
Verification Steps:
Transaction Verification: The first step is to verify the validity of the transaction itself. This involves verifying that:
- The sender has sufficient balance to send the specified amount.
- The transaction is valid according to the rules of the Bitcoin protocol (e.g., amounts, denominations).
UTXO Set Verification
: Next, a node verifies its UTXO set to ensure that all required coins are present in the coinbase address. This verification step helps prevent spam attacks by ensuring that transactions only include valid coins.
Memory pool validation: After verifying the transaction and its dependencies (e.g. witnesses), a node typically checks its memory pool to verify that the transaction is valid for inclusion in the main chain. This involves checking that:
- The transaction has not been rejected by previous nodes.
- The transaction meets the rules of the Bitcoin protocol.
Relay: Once verified, the transaction is relayed further along the network by multiple nodes. This step ensures that the transaction is propagated throughout the network and can be verified by nodes at the end of each block.
Order of nodes:
The order in which these steps occur varies depending on the node configuration, but a typical workflow follows this:
UTXO set verification
: The node starts with this step, ensuring that all required coins are present.
Transaction Verification: The node verifies the transaction against its own rules and the UTXO set to ensure its validity.
Memory Pool Validation: If the transaction passes validation, it is added to the memory pool for relaying.
Low-Resource Basic Checks:
Your initial statement that low-resource basic checks are performed first is partially correct. Although not explicitly mentioned in this article, these checks are indeed performed before other verification steps. However, their primary role is to detect and prevent spam attacks by ensuring that transactions do not contain excessive or invalid amounts.
In summary, the Bitcoin transaction verification process involves a multi-step validation sequence that ensures the integrity and security of the network. The order of verification and the specific checks performed are critical to preventing spam attacks and maintaining community trust.