Bitcoin SV node software v1.0.9 released

Alex Speirs 150 x 150
By Alex Speirs Published: October 19, 2021

Today, Bitcoin Association has released the latest update to the Bitcoin SV node software with version 1.0.9. The update, which was developed by Bitcoin Association’s Bitcoin SV Infrastructure Team, introduces several new features and capabilities, including:

  1. Notification of double spends
  2. Safe mode processing including notification of unusual activity on the network e.g. competing chains and double spends.
  3. Possibility to freeze transaction outputs.

These new additions to the Bitcoin SV node software have been implemented in response to the attempted illegal block re-organisation attacks endured by the network during the third quarter of 2021.  Collectively, the tools facilitate improved monitoring of the Bitcoin SV network by node operators, in addition to enabling new tools to better and more efficiently respond to any potential future attacks on the network to prevent both fraudulent and illegal activity.

Bitcoin SV node software v1.0.9 is available for download now on


Notification of double-spends

Exchanges/miners will be notified of recent double-spends on the Bitcoin SV network.

nChain are building a ‘Double-Spend – Detection and Notification Service’ (DS-DAN) application, that monitors the blockchain and checks for double-spends. The ‘DS-DAN’ is an in-house application and will not initially be released to the public. If a double-spend is detected, the application sends a new DSD P2P notification message to an SV node which will then relay the message to other nodes. The message contains a DS proof (Merkle proof of the inclusion of transactions in a block).  Notifications are distributed via webhooks.


Safe mode – Notification of unusual activity

Exchanges/miners will be notified if a suspicious event (most likely an attack) occurs on the network, triggered by the detection of a recent and long competing chain.

The Bitcoin SV node software currently contains ‘safe mode’ logic to detect competing chains and de-activate wallet RPC calls (put into safe mode). The safe mode logic has been updated so that chain detection is configurable, with notifications triggered via webhooks to alert exchanges/miners/users to the presence of unusual activity.


Possibility to freeze transaction outputs

The node can now ‘freeze’ specific TXOs used by double-spends.

If a freeze is applied to the TXO, the node will not accept transactions that spend the TXO, but will accept external blocks containing transactions that spend the TXO. This solution provides miners with a tool not to include TXOs which are subject to illicit activities, for example following a block re-organisation attack performed by a malicious attacker.

The ability to freeze transaction outputs may also be used by miners to satisfy other legal remedies.

Full details of today’s release can be found in the release notes on