Blockchains en cryptovaluta zijn inmiddels niet meer weg te denken uit het nieuws in welke vorm dan ook. De grondlegger van de techniek en tegelijk bekendste is Bitcoin. Het Bitcoin-netwerk bestaat uit verschillende nodes. En om een node te draaien kun je gebruikmaken van Bitcoin Core, dat in de volksmond ook wel Satoshi-client wordt genoemd. Het Core-ontwikkelteam heeft Bitcoin Core 0.18.0 uitgebracht. De release notes zien er als volgt uit:
Bitcoin Core 0.18.0
Bitcoin Core installation binaries can be downloaded from bitcoincore.org and the source-code is available from the Bitcoin Core source repository.
This is a new major version release, including new features, various bug fixes and performance improvements, as well as updated translations.
Configuration option changes
- Calls to getblocktemplate will fail if the segwit rule is not specified. Calling getblocktemplate without segwit specified is almost certainly a misconfiguration since doing so results in lower rewards for the miner. Failed calls will produce an error message describing how to enable the segwit rule.
systemd init file
- A warning is printed if an unrecognized section name is used in the configuration file. Recognized sections are [test], [main], and [regtest].
- Four new options are available for configuring the maximum number of messages that ZMQ will queue in memory (the “high water mark”) before dropping additional messages. The default value is 1,000, the same as was used for previous releases. See the ZMQ documentation for details.
- The rpcallowip option can no longer be used to automatically listen on all network interfaces. Instead, the rpcbind parameter must be used to specify the IP addresses to listen on. Listening for RPC commands over a public network connection is insecure and should be disabled, so a warning is now printed if a user selects such a configuration. If you need to expose RPC in order to use a tool like Docker, ensure you only bind RPC to your localhost, e.g. docker run [...] -p 127.0.0.1:8332:8332 (this is an extra :8332 over the normal Docker port specification).
- The rpcpassword option now causes a startup error if the password set in the configuration file contains a hash character (#), as it’s ambiguous whether the hash character is meant for the password or as a comment.
- The whitelistforcerelay option is used to relay transactions from whitelisted peers even when not accepted to the mempool. This option now defaults to being off, so that changes in policy and disconnect/ban behavior will not cause a node that is whitelisting another to be dropped by peers. Users can still explicitly enable this behavior with the command line option (and may want to consider contacting the Bitcoin Core project to let us know about their use-case, as this feature could be deprecated in the future).
- The systemd init file (contrib/init/bitcoind.service) has been changed to use /var/lib/bitcoind as the data directory instead of ~bitcoin/.bitcoin. This change makes Bitcoin Core more consistent with other services, and makes the systemd init config more consistent with existing Upstart and OpenRC configs.
- The configuration, PID, and data directories are now completely managed by systemd, which will take care of their creation, permissions, etc. See systemd.exec(5) for more details.
- When using the provided init files under contrib/init, overriding the datadir option in /etc/bitcoin/bitcoin.conf will have no effect. This is because the command line arguments specified in the init files take precedence over the options specified in /etc/bitcoin/bitcoin.conf.
Build system changes
- A new short document about the JSON-RPC interface describes cases where the results of an RPC might contain inconsistencies between data sourced from different subsystems, such as wallet state and mempool state. A note is added to the REST interface documentation indicating that the same rules apply.
- Further information is added to the JSON-RPC documentation about how to secure this interface.
- A new document about the bitcoin.conf file describes how to use it to configure Bitcoin Core.
- A new document introduces Bitcoin Core’s BIP174 Partially-Signed Bitcoin Transactions (PSBT) interface, which is used to allow multiple programs to collaboratively work to create, sign, and broadcast new transactions. This is useful for offline (cold storage) wallets, multisig wallets, coinjoin implementations, and many other cases where two or more programs need to interact to generate a complete transaction.
- The output script descriptor documentation has been updated with information about new features in this still-developing language for describing the output scripts that a wallet or other program wants to receive notifications for, such as which addresses it wants to know received payments. The language is currently used in multiple new and updated RPCs described in these release notes and is expected to be adapted to other RPCs and to the underlying wallet structure.
- A new --disable-bip70 option may be passed to ./configure to prevent Bitcoin-Qt from being built with support for the BIP70 payment protocol or from linking libssl. As the payment protocol has exposed Bitcoin Core to libssl vulnerabilities in the past, builders who don’t need BIP70 support are encouraged to use this option to reduce their exposure to future vulnerabilities.
- The minimum required version of Qt (when building the GUI) has been increased from 5.2 to 5.5.1 (the depends system provides 5.9.7)
- getnodeaddresses returns peer addresses known to this node. It may be used to find nodes to connect to without using a DNS seeder.
- listwalletdir returns a list of wallets in the wallet directory (either the default wallet directory or the directory configured by the -walletdir parameter).
- getrpcinfo returns runtime details of the RPC server. At the moment, it returns an array of the currently active commands and how long they’ve been running.
- deriveaddresses returns one or more addresses corresponding to an output descriptor.
- getdescriptorinfo accepts a descriptor and returns information about it, including its computed checksum.
- joinpsbts merges multiple distinct PSBTs into a single PSBT. The multiple PSBTs must have different inputs. The resulting PSBT will contain every input and output from all of the PSBTs. Any signatures provided in any of the PSBTs will be dropped.
- analyzepsbt examines a PSBT and provides information about what the PSBT contains and the next steps that need to be taken in order to complete the transaction. For each input of a PSBT, analyzepsbt provides information about what information is missing for that input, including whether a UTXO needs to be provided, what pubkeys still need to be provided, which scripts need to be provided, and what signatures are still needed. Every input will also list which role is needed to complete that input, and analyzepsbt will also list the next role in general needed to complete the PSBT. analyzepsbt will also provide the estimated fee rate and estimated virtual size of the completed transaction if it has enough information to do so.
- utxoupdatepsbt searches the set of Unspent Transaction Outputs (UTXOs) to find the outputs being spent by the partial transaction. PSBTs need to have the UTXOs being spent to be provided because the signing algorithm requires information from the UTXO being spent. For segwit inputs, only the UTXO itself is necessary. For non-segwit outputs, the entire previous transaction is needed so that signers can be sure that they are signing the correct thing. Unfortunately, because the UTXO set only contains UTXOs and not full transactions, utxoupdatepsbt will only add the UTXO for segwit inputs.
Note: some low-level RPC changes mainly useful for testing are described in the Low-level Changes section below.
Deprecated or removed RPCs
- getpeerinfo now returns an additional minfeefilter field set to the peer’s BIP133 fee filter. You can use this to detect that you have peers that are willing to accept transactions below the default minimum relay fee.
- The mempool RPCs, such as getrawmempool with verbose=true, now return an additional “bip125-replaceable” value indicating whether the transaction (or its unconfirmed ancestors) opts-in to asking nodes and miners to replace it with a higher-feerate transaction spending any of the same inputs.
- settxfee previously silently ignored attempts to set the fee below the allowed minimums. It now prints a warning. The special value of “0” may still be used to request the minimum value.
- getaddressinfo now provides an ischange field indicating whether the wallet used the address in a change output.
- importmulti has been updated to support P2WSH, P2WPKH, P2SH-P2WPKH, and P2SH-P2WSH. Requests for P2WSH and P2SH-P2WSH accept an additional witnessscript parameter.
- importmulti now returns an additional warnings field for each request with an array of strings explaining when fields are being ignored or are inconsistent, if there are any.
- getaddressinfo now returns an additional solvable boolean field when Bitcoin Core knows enough about the address’s scriptPubKey, optional redeemScript, and optional witnessScript in order for the wallet to be able to generate an unsigned input spending funds sent to that address.
- The getaddressinfo, listunspent, and scantxoutset RPCs now return an additional desc field that contains an output descriptor containing all key paths and signing information for the address (except for the private key). The desc field is only returned for getaddressinfo and listunspent when the address is solvable.
- importprivkey will preserve previously-set labels for addresses or public keys corresponding to the private key being imported. For example, if you imported a watch-only address with the label “cold wallet” in earlier releases of Bitcoin Core, subsequently importing the private key would default to resetting the address’s label to the default empty-string label (“”). In this release, the previous label of “cold wallet” will be retained. If you optionally specify any label besides the default when calling importprivkey, the new label will be applied to the address.
- See the Mining section for changes to getblocktemplate.
- getmininginfo now omits currentblockweight and currentblocktx when a block was never assembled via RPC on this node.
- The getrawtransaction RPC & REST endpoints no longer check the unspent UTXO set for a transaction. The remaining behaviors are as follows: 1. If a blockhash is provided, check the corresponding block. 2. If no blockhash is provided, check the mempool. 3. If no blockhash is provided but txindex is enabled, also check txindex.
- unloadwallet is now synchronous, meaning it will not return until the wallet is fully unloaded.
- importmulti now supports importing of addresses from descriptors. A “desc” parameter can be provided instead of the “scriptPubKey” in a request, as well as an optional range for ranged descriptors to specify the start and end of the range to import. Descriptors with key origin information imported through importmulti will have their key origin information stored in the wallet for use with creating PSBTs. More information about descriptors can be found here.
- listunspent has been modified so that it also returns witnessScript, the witness script in the case of a P2WSH or P2SH-P2WSH output.
- createwallet now has an optional blank argument that can be used to create a blank wallet. Blank wallets do not have any keys or HD seed. They cannot be opened in software older than 0.18. Once a blank wallet has a HD seed set (by using sethdseed) or private keys, scripts, addresses, and other watch only things have been imported, the wallet is no longer blank and can be opened in 0.17.x. Encrypting a blank wallet will also set a HD seed for it.
- signrawtransaction is removed after being deprecated and hidden behind a special configuration option in version 0.17.0.
- The ‘account’ API is removed after being deprecated in v0.17. The ‘label’ API was introduced in v0.17 as a replacement for accounts. See the release notes from v0.17 for a full description of the changes from the ‘account’ API to the ‘label’ API.
- addwitnessaddress is removed after being deprecated in version 0.16.0.
- generate is deprecated and will be fully removed in a subsequent major version. This RPC is only used for testing, but its implementation reached across multiple subsystems (wallet and mining), so it is being deprecated to simplify the wallet-node interface. Projects that are using generate for testing purposes should transition to using the generatetoaddress RPC, which does not require or use the wallet component. Calling generatetoaddress with an address returned by the getnewaddress RPC gives the same functionality as the old generate RPC. To continue using generate in this version, restart bitcoind with the -deprecatedrpc=generate configuration option.
- Be reminded that parts of the validateaddress command have been deprecated and moved to getaddressinfo. The following deprecated fields have moved to getaddressinfo: ismine, iswatchonly, script, hex, pubkeys, sigsrequired, pubkey, embedded, iscompressed, label, timestamp, hdkeypath, hdmasterkeyid.
- The addresses field has been removed from the validateaddress and getaddressinfo RPC methods. This field was confusing since it referred to public keys using their P2PKH address. Clients should use the embedded.address field for P2SH or P2WSH wrapped addresses, and pubkeys for inspecting multisig participants.
Graphical User Interface (GUI)
- A new /rest/blockhashbyheight/ endpoint is added for fetching the hash of the block in the current best blockchain based on its height (how many blocks it is after the Genesis Block).
- A new Window menu is added alongside the existing File, Settings, and Help menus. Several items from the other menus that opened new windows have been moved to this new Window menu.
- In the Send tab, the checkbox for “pay only the required fee” has been removed. Instead, the user can simply decrease the value in the Custom Feerate field all the way down to the node’s configured minimum relay fee.
- In the Overview tab, the watch-only balance will be the only balance shown if the wallet was created using the createwallet RPC and the disable_private_keys parameter was set to true.
- The launch-on-startup option is no longer available on macOS if compiled with macosx min version greater than 10.11 (use CXXFLAGS=”-mmacosx-version-min=10.11” CFLAGS=”-mmacosx-version-min=10.11” for setting the deployment sdk version)
- A new bitcoin-wallet tool is now distributed alongside Bitcoin Core’s other executables. Without needing to use any RPCs, this tool can currently create a new wallet file or display some basic information about an existing wallet, such as whether the wallet is encrypted, whether it uses an HD seed, how many transactions it contains, and how many address book entries it has.
This section describes planned changes to Bitcoin Core that may affect other Bitcoin software and services.
Deprecated P2P messages
- Since version 0.16.0, Bitcoin Core’s built-in wallet has defaulted to generating P2SH-wrapped segwit addresses when users want to receive payments. These addresses are backwards compatible with all widely-used software. Starting with Bitcoin Core 0.20 (expected about a year after 0.18), Bitcoin Core will default to native segwit addresses (bech32) that provide additional fee savings and other benefits. Currently, many wallets and services already support sending to bech32 addresses, and if the Bitcoin Core project sees enough additional adoption, it will instead default to bech32 receiving addresses in Bitcoin Core 0.19 (approximately November 2019). P2SH-wrapped segwit addresses will continue to be provided if the user requests them in the GUI or by RPC, and anyone who doesn’t want the update will be able to configure their default address type. (Similarly, pioneering users who want to change their default now may set the addresstype=bech32 configuration option in any Bitcoin Core release from 0.16.0 up.)
- BIP 61 reject messages are now deprecated. Reject messages have no use case on the P2P network and are only logged for debugging by most network nodes. Furthermore, they increase bandwidth and can be harmful for privacy and security. It has been possible to disable BIP 61 messages since v0.17 with the -enablebip61=0 option. BIP 61 messages will be disabled by default in a future version, before being removed entirely.
This section describes RPC changes mainly useful for testing, mostly not relevant in production. The changes are mentioned for completeness.
- The submitblock RPC previously returned the reason a rejected block was invalid the first time it processed that block, but returned a generic “duplicate” rejection message on subsequent occasions it processed the same block. It now always returns the fundamental reason for rejecting an invalid block and only returns “duplicate” for valid blocks it has already accepted.
- A new submitheader RPC allows submitting block headers independently from their block. This is likely only useful for testing.
- The signrawtransactionwithkey and signrawtransactionwithwallet RPCs have been modified so that they also optionally accept a witnessScript, the witness script in the case of a P2WSH or P2SH-P2WSH output. This is compatible with the change to listunspent.
- For the walletprocesspsbt and walletcreatefundedpsbt RPCs, if the bip32derivs parameter is set to true but the key metadata for a public key has not been updated yet, then that key will have a derivation path as if it were just an independent key (i.e. no derivation path and its master fingerprint is itself).
- The -usehd configuration option was removed in version 0.16. From that version onwards, all new wallets created are hierarchical deterministic wallets. This release makes specifying -usehd an invalid configuration option.
- This release allows peers that your node automatically disconnected for misbehavior (e.g. sending invalid data) to reconnect to your node if you have unused incoming connection slots. If your slots fill up, a misbehaving node will be disconnected to make room for nodes without a history of problems (unless the misbehaving node helps your node in some other way, such as by connecting to a part of the Internet from which you don’t have many other peers). Previously, Bitcoin Core banned the IP addresses of misbehaving peers for a period of time (default of 1 day); this was easily circumvented by attackers with multiple IP addresses. If you manually ban a peer, such as by using the setban RPC, all connections from that peer will still be rejected.
- The key metadata will need to be upgraded the first time that the HD seed is available. For unencrypted wallets this will occur on wallet loading. For encrypted wallets this will occur the first time the wallet is unlocked.
- Newly encrypted wallets will no longer require restarting the software. Instead such wallets will be completely unloaded and reloaded to achieve the same effect.
- A sub-project of Bitcoin Core now provides Hardware Wallet Interaction (HWI) scripts that allow command-line users to use several popular hardware key management devices with Bitcoin Core. See their project page for details.
Changes for particular platforms
- This release changes the Random Number Generator (RNG) used from OpenSSL to Bitcoin Core’s own implementation, although entropy gathered by Bitcoin Core is fed out to OpenSSL and then read back in when the program needs strong randomness. This moves Bitcoin Core a little closer to no longer needing to depend on OpenSSL, a dependency that has caused security issues in the past. The new implementation gathers entropy from multiple sources, including from hardware supporting the rdseed CPU instruction.
- On macOS, Bitcoin Core now opts out of application CPU throttling (“app nap”) during initial blockchain download, when catching up from over 100 blocks behind the current chain tip, or when reindexing chain data. This helps prevent these operations from taking an excessively long time because the operating system is attempting to conserve power.