Viacoin Core 0.16.3

4 min readMay 20, 2019

We have recently released Viacoin Core 0.16.3, which is packed with new features, improvements and fixes. In this article we will briefly walk through all of the Viacoin Core 0.16.3 features.

Viacoin Core 0.16.3 changelog:

Segwit Wallet
Bech32 address support
HD-wallets by default
Replace-By-Fee by default in GUI
Block Relay Improvements
Support for signalling pruned nodes
SHA256 assembly enabled by default
GUI changes
RPC changes + changed command line options

Segwit Wallet

Viacoin Core 0.16.3 introduces full support for segwit in the wallet and user interfaces. It now supports legacy, p2sh-segwit (default) and bech32 addresses.

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

Bech32 address support

Full support for native segwit addresses Bech32 has now been added. This includes the ability to send to Bech32 addresses (including non-v0 ones), and generating these addresses. 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. Bech32 addresses start with ‘via1’.

HD-wallets by default

Due to a backward-incompatible change in the wallet database, wallets created with version 0.16.3 will be rejected by previous versions. Also, version 0.16.3 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. More information about HD-wallets can be found HERE.

Replace-By-Fee by default in GUI

The send screen now uses Replace-By-Fee by default. There is a checkbox to mark the transaction as final. The RPC default remains unchanged: to use RBF, launch with -walletrbf=1 or use the replaceable argument for individual transactions.

Wallets directory configuration

Viacoin 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 viacoin 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-walletdir=<path> option where <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.

Support for signalling pruned nodes

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.

SHA256 assembly enabled by default

The SHA256 hashing optimizations for architectures supporting SSE4, which lead to ~50% speedups in SHA256 on supported hardware (~5% faster synchronization and block validation), have now been enabled by default. In previous versions they were enabled using the --enable-experimental-asm flag when building, but are now the default and no longer deemed experimental.

GUI changes

Viacoin Core 0.16.3 also comes with a few GUI changes:

Uses of “µVIA” 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.

RPC changes + changed command line options

Viacoin Core 0.16.3 also comes with RPC changes and a few changed command line options. To prevent this article from becoming extremely long, we have published these changes HERE.