BasicSwap v0.17.7 is a critical security release. It fixes a flaw in how BasicSwap validated a signature received from a swap counterparty on adaptor-signature (Monero-style) swaps, and it repairs any swap already caught by it. Everyone running these swaps should install it without delay. Alongside the security fix, the automated market maker now reserves fees when it sizes offers, and bids on revoked offers are turned away.

Most Notable Updates 💡

The Security Fix: Adaptor-Signature Swaps 🔒

v0.17.7 closes a gap in how BasicSwap validated a signature received from the swap counterparty on the script side (coin A) of an adaptor-signature swap. A counterparty running modified software could use that gap to leave your coin-A lock in a state that could not be spent as intended, so the swap would stall and need manual recovery to refund. It cannot be used to steal coins, but a swap can be trapped until it is recovered, so if you run adaptor-signature swaps you should treat this as a mandatory update.

The release also cleans up after the issue. If a coin-A lock was already left in the affected state, v0.17.7 rebuilds its refund transaction so the swap can refund on its own, with no manual steps (commits 5a85097, 71cec85, PR #629).

The scope is narrow. It affects only the script side of adaptor-signature swaps on Bitcoin-derived coins, and Bitcoin Cash is not affected. If you run adaptor-signature swaps, update to v0.17.7 without delay. There is nothing else to do.

AMM: Fee-Aware Offer Sizing 🤖

The automated market maker now sets aside an estimated network fee when it sizes an offer, so it no longer posts an offer larger than your wallet can actually fund once the fee is paid. A new fee_reserve_mult setting controls the margin, defaulting to 4, and a template is skipped while no fee estimate is available (commit f1b790e, PR #615).

Two related changes came with it. When the AMM reposts a fixed-total or one-time template, it now counts the amounts already committed to in-flight swaps, so a repost is never sized above what is still spendable (commit 7f039ad, PR #615). And it reads each coin's balance once per loop rather than once per template, which is lighter on the wallet when you run many templates (commit 51e5276, PR #615).

Smaller Fixes 🧹

Bids on revoked or inactive offers are now rejected on both sides. You cannot place a bid on an offer that has been revoked or gone inactive, and a bid that arrives for one is dropped rather than processed (commit 5f6a7a1, PR #628).

Under the hood, v0.17.7 replaces assert with an explicit check throughout, so those checks still run when Python is started with optimisations enabled, and it now verifies a keyshare recovered from a counterparty's on-chain data against the pubkey agreed during the bid, so a bad recovery is reported by its cause rather than surfacing later as an unexplained failure (commits 27371262, 5a85097, PR #629).

Install the Latest BasicSwap Update 🖥️

To install, update BasicSwap through the usual process and relaunch.

Docker

If you've installed BasicSwap following the Docker method:

1. Shutdown BasicSwap properly and stop the Docker image (docker-compose stop),
2. From the basicswap folder, type the git pull command,
3. In the /docker folder, run the docker-compose build --no-cache command,
4. Once the process completes, launch BasicSwap again using the docker-compose up command.

Note: Depending on your Docker version, adding a dash between docker and compose may not be necessary and may instead throw an error.

Non-Docker

If you've installed BasicSwap following the non-Docker method:

1. Shutdown BasicSwap properly,
2. From the ~/coinswaps/basicswap folder, type the git pull command,
3. Execute the following command: source ~/coinswaps/venv/bin/activate
4. Execute the following command: pip install --require-hashes -r requirements.txt,
5. Execute the following command: pip3 install .,
6. Launch BasicSwap as usual.

Install Script

If you've installed BasicSwap using Nahuhh's GitHub installation script:

• Execute the update command: bsx-update.

Changelog 📝

The full v0.17.7 changelog, grouped by area. It covers 4 pull requests (#607, #615, #628 and #629).

Security

• Adaptor-sig swaps: tighten validation of a signature received from a peer, closing a way a counterparty could disrupt a swap [5a85097] / PR #629
• Adaptor-sig swaps: automatically repair an affected coin-A lock refund transaction so the swap can refund without manual recovery [71cec85] / PR #629

AMM

• Reserve an estimated network fee when sizing offers, with a new fee_reserve_mult option (default 4) [f1b790e] / PR #615
• Account for in-flight amounts when reposting fixed-total and one-time templates [7f039ad] / PR #615
• Fetch each coin's wallet balance once per loop instead of once per template [51e5276] / PR #615

Fixes

• Reject bids placed on, and bids received for, revoked or inactive offers [5f6a7a1] / PR #628

Refactors

• Replace assert with an explicit check throughout, and verify a recovered keyshare against the pubkey agreed during the bid [27371262] [5a85097] / PR #629

Build

• Bump actions/setup-python from 6 to 7 [553781d] / PR #607

You can inspect all changes by verifying the v0.17.6 to v0.17.7 comparison page here.

Stay Connected

Keep up with BasicSwap on social media:

• Twitter: @basicswapdex
• Matrix: BasicSwap channel
• GitHub: BasicSwap repositories
• Support the project: Donation page