BUIP085: Double spend relaying
Proposer: Gal Buki (@torusJKL)
Submitted on: 2018-02-04
Status: passed


## Background

A double spend can happen within the time from the initial broadcast
until the transaction is included in a block. Although this is on
average within 10 minutes at the point of sale we need to know that a
unconfirmed transaction is as safe as possible withing seconds.

Currently double spend transactions are not relayed thus a merchant
might not know that there is a high chance of him not receiving his
transaction. In order to detect double spends those transactions need to
be forwarded by the nodes.

## Motivation

By receiving and forwarding double spend transactions sellers learn
about attempts to defraud them faster and can take appropriate steps.
This will make 0-conf transaction on Bitcoin Cash more safe and will

1. Develop a double spend relaying that is compatible with BitcoinXT’s
implementation (the relaying as such and the rpc call).
2. Add a double spend visualization in the wallet GUI.

## Timeline

The double spend proof should be developed and to be implemented for
BUCash with the aim of being ready for inclusion in the scheduled