Feature: Cancel Transaction via RBF

[prusnak]

Currently there are two options what an user can do with a RBF transaction:

• Bump Fee (create transaction with identical inputs but with higher fee = decreased change address amount)
• Finalize Transaction (create identical transaction but with RBF flag disabled

See https://trezor.io/learn/a/rbf-in-trezor-suite-app for more details

Originally, were considering adding a third option:

• Cancel Transaction (create transaction with identical inputs, with higher fee, but send all coins to a single change address = remove outputs that don't belong to Trezor from the TX)

In the end, we haven't added it, since this would provide an easy way for a user to fool merchants accepting 0-conf TXs via a double spend.

However, it seems the cat is out of the bag and other wallets have already added it, so we might want to add it as well:

• Blue Wallet - https://twitter.com/bluewalletio/status/1263038542340591617
• Electrum - https://github.com/spesmilo/electrum/pull/6641
• OBW - https://github.com/nbd-wtf/obw

[gubatron]

If you think that the "Cancel transaction" feature should be implemented, let us know in the GitHub issue

Yes please!

[prusnak]

Good point from Stephan Livera:

The feature name can confuse some users if they attempt it and it fails. Maybe something like 'Attempt to cancel'?

[danielkonecny]

I also think this would be a good functionality. It improves usability of bitcoin and also motivates merchants to use LN for smaller transactions (and non-0-conf for larger). Definitely a better practice than 0-conf relying on trust in the customer.

[alicercedigital]

The absence of this functionality is a significant flaw in Trezor.

To fix pending transactions that do not have 200% of the funds, we need to use another wallet such as Metamask. This, however, could make my wallet insecure, and thus make the Trezor ineffective.

This issue needs to be addressed, as it is causing problems for many Trezor users. A quick search for "not enough funds bump fee trezor" reveals a significant number of users who have suffered losses or other issues that could have been prevented with this functionality.

[Zerebokep]

Please implement this.

[spazcoin]

Yes please implement this. My use-case: Interlay wraps BTC into iBTC on the Polkadot network. But they have a 12 hour window for BTC transactions to be confirmed. If not confirmed within 12 hours the Interlay protocol will mark that Interlay transaction as not having been satisfied and will mark it as "cancelled". I've asked them several times and their XCLAIM protocol can't proof a transaction in the mempool and can only generate a proof for a confirmed transaction. So now once the delayed Bitcoin transaction is finally processed, the original destination BTC accounts will receive funds but no Interlay iBTC tokens will be generated. But since Trezor doesn't support double-spend transactions, I have no way to force the original (non-confirmed) transaction to fail now.