UFO 0.16 Released
June 3, 2018
Uniform Fiscal Object
The 0.16 wallet can be downloaded from the following release page on GitHub:
Bitcoin Core 0.16.0 introduces full support for segwit in the wallet and user interfaces. A new
-addresstype argument has been added, which supports
p2sh-segwit (default), and
bech32 addresses. It controls what kind of addresses are produced by
-changetype argument has also been added, with the same options, and by default equal to
-addresstype, to control which kind of change is used.
address_type parameter has been added to the
addmultisigaddress RPCs to specify which type of address to generate. A
change_type argument has been added to the
fundrawtransaction RPC to override the
-changetype argument for specific transactions.
- All segwit addresses created through
*multisigRPCs explicitly get their redeemscripts added to the wallet file. This means that downgrading after creating a segwit address will work, as long as the wallet file is up to date.
- All segwit keys in the wallet get an implicit redeemscript added, without it being written to the file. This means recovery of an old backup will work, as long as you use new software.
- All keypool keys that are seen used in transactions explicitly get their redeemscripts added to the wallet files. This means that downgrading after recovering from a backup that includes a segwit address will work
Note that some RPCs do not yet support segwit addresses. Notably,
verifymessage doesn’t support segwit addresses, nor does
importmulti at this time. Support for segwit in those RPCs will continue to be added in future versions.
P2WPKH change outputs are now used by default if any destination in the transaction is a P2WPKH or P2WSH output. This is done to ensure the change output is as indistinguishable from the other outputs as possible in either case.
BIP173 (Bech32) Address support (“uf1…” addresses)
Full support for native segwit addresses (BIP173 / Bech32) has now been added. This includes the ability to send to BIP173 addresses (including non-v0 ones), and generating these addresses (including as default new addresses, see above).
A checkbox has been added to the GUI to select whether a Bech32 address or P2SH-wrapped address should be generated when using segwit addresses. When launched with
-addresstype=bech32 it is checked by default. When launched with
-addresstype=legacy it is unchecked and disabled.
HD-wallets by default
Due to a backward-incompatible change in the wallet database, wallets created with version 0.16.0 will be rejected by previous versions. Also, version 0.16.0 will only create hierarchical deterministic (HD) wallets. Note that this only applies to new wallets; wallets made with previous versions will not be upgraded to be HD.
Wallets directory configuration (
Bitcoin Core now has more flexibility in where the wallets directory can be located. Previously wallet database files were stored at the top level of the bitcoin data directory. The behavior is now:
- For new installations (where the data directory doesn’t already exist), wallets will now be stored in a new
wallets/subdirectory inside the data directory by default.
- For existing nodes (where the data directory already exists), wallets will be stored in the data directory root by default. If a
wallets/subdirectory already exists in the data directory root, then wallets will be stored in the
wallets/subdirectory by default.
- The location of the wallets directory can be overridden by specifying a
<path>can be an absolute path to a directory or directory symlink.
Care should be taken when choosing the wallets directory location, as if it becomes unavailable during operation, funds may be lost.
Build: Minimum GCC bumped to 4.8.x
The minimum version of the GCC compiler required to compile Bitcoin Core is now 4.8. No effort will be made to support older versions of GCC. See discussion in issue #11732 for more information. The minimum version for the Clang compiler is still 3.3. Other minimum dependency versions can be found in
doc/dependencies.md in the repository.
Support for signalling pruned nodes (BIP159)
Pruned nodes can now signal BIP159’s NODE_NETWORK_LIMITED using service bits, in preparation for full BIP159 support in later versions. This would allow pruned nodes to serve the most recent blocks. However, the current change does not yet include support for connecting to these pruned peers.
- Uses of “µBTC” in the GUI now also show the more colloquial term “bits”, specified in BIP176.
- The option to reuse a previous address has now been removed. This was justified by the need to “resend” an invoice, but now that we have the request history, that need should be gone.
- Support for searching by TXID has been added, rather than just address and label.
- A “Use available balance” option has been added to the send coins dialog, to add the remaining available wallet balance to a transaction output.
- A toggle for unblinding the password fields on the password dialog has been added.
A new RPC
rescanblockchain has been added to manually invoke a blockchain rescan. The RPC supports start and end-height arguments for the rescan, and can be used in a multiwallet environment to rescan the blockchain at runtime.
savemempool RPC has been added which allows the current mempool to be saved to disk at any time to avoid it being lost due to crashes / power loss.
Safe mode disabled by default
Safe mode is now disabled by default and must be manually enabled (with
-disablesafemode=0) if you wish to use it. Safe mode is a feature that disables a subset of RPC calls – mostly related to the wallet and sending – automatically in case certain problem conditions with the network are detected. However, developers have come to regard these checks as not reliable enough to act on automatically. Even with safe mode disabled, they will still cause warnings in the
warnings field of the
getneworkinfo RPC and launch the
Renamed script for creating JSON-RPC credentials
share/rpcuser/rpcuser.py script was renamed to
share/rpcauth/rpcauth.py. This script can be used to create
rpcauth credentials for a JSON-RPC user.
validateaddress RPC output has been extended with a few new fields, and support for segwit addresses (both P2SH and Bech32). Specifically: * A new field
iswitness is True for P2WPKH and P2WSH addresses (“uf1…” addresses), but not for P2SH-wrapped segwit addresses (see below). * The existing field
isscript will now also report True for P2WSH addresses. * A new field
embedded is present for all script addresses where the script is known and matches something that can be interpreted as a known address. This is particularly true for P2SH-P2WPKH and P2SH-P2WSH addresses. The value for
embedded includes much of the information
validateaddress would report if invoked directly on the embedded address. * For multisig scripts a new
pubkeys field was added that reports the full public keys involved in the script (if known). This is a replacement for the existing
addressesfield (which reports the same information but encoded as P2PKH addresses), represented in a more useful and less confusing way. The
addresses field remains present for non-segwit addresses for backward compatibility. * For all single-key addresses with known key (even when wrapped in P2SH or P2WSH), the
pubkeyfield will be present. In particular, this means that invoking
validateaddress on the output of
getnewaddress will always report the
pubkey, even when the address type is P2SH-P2WPKH.
- The deprecated RPC
getinfowas removed. It is recommended that the more specific RPCs are used:
- The wallet RPC
getreceivedbyaddresswill return an error if called with an address not in the wallet.
- The wallet RPC
addwitnessaddresswas deprecated and will be removed in version 0.17, set the
getnewaddress, or option
dumpwalletnow includes hex-encoded scripts from the wallet in the dumpfile, and
importwalletnow imports these scripts, but corresponding addresses may not be added correctly or a manual rescan may be required to find relevant transactions.
- The RPC
getblockchaininfonow includes an
- A new
blockhashparameter has been added to the
getrawtransactionRPC which allows for a raw transaction to be fetched from a specific block if known, even without
fundrawtransactionRPCs now have optional
iswitnessparameters to override the heuristic witness checks if necessary.
walletpassphrasetimeout is now clamped to 2^30 seconds.
- Using addresses with the
createmultisigRPC is now deprecated, and will be removed in a later version. Public keys should be used instead.
- Blockchain rescans now no longer lock the wallet for the entire rescan process, so other RPCs can now be used at the same time (although results of balances / transactions may be incorrect or incomplete until the rescan is complete).
loggingRPC has now been made public rather than hidden.
initialblockdownloadboolean has been added to the
getblockchaininfoRPC to indicate whether the node is currently in IBD or not.
minrelaytxfeeis now included in the output of
Other changed command-line options
-debuglogfile=<file>can be used to specify an alternative debug logging file.
- bitcoin-cli now has an
-stdinrpcpassoption to allow the RPC password to be read from standard input.
-usehdoption has been removed.
- bitcoin-cli now supports a new
-getinfoflag which returns an output like that of the now-removed