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Because the blockchain is of significant size, tens of Gigabytes so far, this can be challenging for users. It is therefore for most users recommended to use thin wallets. There is also a third kind of wallet to be mentioned, which can be called a third-party wallet. These wallets only connect the user to a third-party, usually a bitcoin company, which manages the addresses and keys of the user for him or her.
The device of the user therefore doesn't actually run a wallet, but more of a connection program to the wallet which is actually running on the companies servers. Some third-party wallet providers allow transactions between users who both use the same wallet company, to have instantly confirmed transactions, sending bitcoins not to cumbersome addresses but e-mail-address-, and social network handles.
This can make them more convenient for the user, but they also come with risk. Because the company holds the keys, its owners can simply run off with the users bitcoins, they can be pressured by governments to give agencies information about their users and so on.
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Bitcoin Core provides testing tools designed to let developers test their applications with reduced risks and limitations. Testnet also relaxes some restrictions such as standard transaction checks so you can test functions which might currently be disabled by default on mainnet. Many developers consider regtest mode the preferred way to develop new applications. The following example will let you create a regtest environment after you first configure bitcoind. Start bitcoind in regtest mode to create a private block chain.
Generate blocks using a special RPC which is only available in regtest mode. This takes less than a second on a generic PC. Unlike mainnet , in regtest mode only the first blocks pay a reward of 50 bitcoins. However, a block must have confirmations before that reward can be spent, so we generate blocks to get access to the coinbase transaction from block 1. Verify that we now have 50 bitcoins available to spend. Regtest wallets and block chain state chainstate are saved in the regtest subdirectory of the Bitcoin Core configuration directory.
You can safely delete the regtest subdirectory and restart Bitcoin Core to start a new regtest. See the Developer Examples Introduction for default configuration directory locations on various operating systems. Always back up mainnet wallets before performing dangerous operations such as deleting. Creating transactions is something most Bitcoin applications do.
Your applications may use something besides Bitcoin Core to create transactions, but in any system, you will need to provide the same kinds of data to create transactions with the same attributes as those described below. In order to use this tutorial, you will need to setup Bitcoin Core and create a regression test mode environment with 50 BTC in your test wallet. Bitcoin Core provides several RPCs which handle all the details of spending, including creating change outputs and paying appropriate fees.
Even advanced users should use these RPCs whenever possible to decrease the chance that satoshis will be lost by mistake. Send 10 bitcoins to the address using the sendtoaddress RPC. The returned hex string is the transaction identifier txid.
In this case, it withdrew the satoshis from our only available UTXO , the coinbase transaction for block 1 which matured with the creation of block The first UTXO shown is a change output that sendtoaddress created using a new address from the key pool. The second UTXO shown is the spend to the address we provided. If we had spent those satoshis to someone else, that second transaction would not be displayed in our list of UTXOs. Create a new block to confirm the transaction above takes less than a second and clear the shell variable.
The raw transaction RPCs allow users to create custom transactions and delay broadcasting those transactions. However, mistakes made in raw transactions may not be detected by Bitcoin Core, and a number of raw transaction users have permanently lost large numbers of satoshis , so please be careful using raw transactions on mainnet.
This subsection covers one of the simplest possible raw transactions. We now have three UTXOs: We save the txid and output index number vout of that coinbase UTXO to shell variables. Get a new address to use in the raw transaction. Creating transactions is something most Bitcoin applications do. Your applications may use something besides Bitcoin Core to create transactions, but in any system, you will need to provide the same kinds of data to create transactions with the same attributes as those described below.
In order to use this tutorial, you will need to setup Bitcoin Core and create a regression test mode environment with 50 BTC in your test wallet. Bitcoin Core provides several RPCs which handle all the details of spending, including creating change outputs and paying appropriate fees.
Even advanced users should use these RPCs whenever possible to decrease the chance that satoshis will be lost by mistake. Send 10 bitcoins to the address using the sendtoaddress RPC. The returned hex string is the transaction identifier txid.
In this case, it withdrew the satoshis from our only available UTXO , the coinbase transaction for block 1 which matured with the creation of block The first UTXO shown is a change output that sendtoaddress created using a new address from the key pool.
The second UTXO shown is the spend to the address we provided. If we had spent those satoshis to someone else, that second transaction would not be displayed in our list of UTXOs.
Create a new block to confirm the transaction above takes less than a second and clear the shell variable. The raw transaction RPCs allow users to create custom transactions and delay broadcasting those transactions. However, mistakes made in raw transactions may not be detected by Bitcoin Core, and a number of raw transaction users have permanently lost large numbers of satoshis , so please be careful using raw transactions on mainnet. This subsection covers one of the simplest possible raw transactions.
We now have three UTXOs: We save the txid and output index number vout of that coinbase UTXO to shell variables. Get a new address to use in the raw transaction. Using two arguments to the createrawtransaction RPC , we create a new raw format transaction. The first argument a JSON array references the txid of the coinbase transaction from block 2 and the index number 0 of the output from that transaction we want to spend.
The second argument a JSON object creates the output with the address public key hash and number of bitcoins we want to transfer. We save the resulting raw format transaction to a shell variable. In this example, our input had See the Complex Raw Transaction subsection below for how to create a transaction with multiple outputs so you can send the change back to yourself.
Use the decoderawtransaction RPC to see exactly what the transaction we just created does. Send the signed transaction to the connected node using the sendrawtransaction RPC.
Generate a block to confirm the transaction and clear our shell variables. For our two inputs , we select two UTXOs by placing the txid and output index numbers vouts in shell variables. We also save the addresses corresponding to the public keys hashed or unhashed used in those transactions.
We need the addresses so we can get the corresponding private keys from our wallet. We need the private keys so we can sign each of the inputs separately. Users should never manually manage private keys on mainnet. These examples are to help you learn, not for you to emulate on mainnet. For our two outputs , get two new addresses. Create the raw transaction using createrawtransaction much the same as before, except now we have two inputs and two outputs.