This week’s newsletter contains a warning about backdoored VM images.
Also included are our regular sections with summaries of notable
improvements to clients and services, announcements of releases and
release candidates, and changes to popular Bitcoin infrastructure
- ● Backdoored VM images: a user on Reddit posted
about losing funds after using an AWS image that came with a Bitcoin
full node already installed and synced to a recent block. Although
the source of the loss was not fully determined in the thread, it was
suggested that virtual machine images or other curated collections of
software, especially those designed for Bitcoin or other
cryptocurrencies, provide an effective mechanism for delivering
backdoored software to valuable servers. This is a reminder that you
should only install software from trustworthy sources. Additionally,
please remember that your VM provider and their support staff can
likely access any private keys on your server even if you perfect
every other aspect of your security. In short, please consider
performing extra diligence on any software or service to which you
will entrust the creation of non-reversible Bitcoin transactions.
No significant Bitcoin technical news this week.
Changes to services and client software
In this monthly feature, we highlight interesting updates to Bitcoin
wallets and services.
● Sparrow Wallet adds payment batching and payjoin:
Sparrow’s recent 0.9.6 and 0.9.7 releases
added payment batching and payjoin capabilities respectively.
● Nunchuk open sources Bitcoin Core backed multisig library:
The team that developed the Nunchuk desktop application has
libnunchuk, a C++ multisig library that leverages
Bitcoin Core’s existing codebase.
Releases and release candidates
New releases and release candidates for popular Bitcoin infrastructure
projects. Please consider upgrading to new releases or helping to test
- ● C-Lightning 0.9.2rc1 is a release candidate for
the next maintenance version of C-Lightning. It contains new
features, updated options, and bug fixes.
Notable code and documentation changes
Notable changes this week in Bitcoin Core,
C-Lightning, Eclair, LND,
Hardware Wallet Interface (HWI), Bitcoin Improvement Proposals
(BIPs), and Lightning BOLTs.
● C-Lightning #4168 adds the ability for a plugin to specify that a hook be
run before or after that of another plugin. Plugin authors wishing to ensure
their plugin’s relative load ordering in this way should amend their
getmanifestmethod’s response as shown here.
● C-Lightning #4171 updates the
hsmtoolcommand with a new
dumponchaindescriptorsparameter that prints the output script
descriptors for the keys and scripts used by
C-Lightning’s onchain wallet. These descriptors may then be imported
into a watch-only wallet to track any onchain transactions made
by the LN node. This feature was requested to help improve integration between BTCPay
Server’s default hot wallet and the optional LN server.
● Eclair #1599 makes spending more intelligent when considering
sending a multipath payment to a channel
counterparty. When the receiver shares a direct channel with the
spender, the spender knows exactly how much money is available to be
sent in that channel. With this change, up to that amount can be
allocated to the initial part of the payment instead of splitting it
across multiple paths. Any remainder that still needs to be sent can
still use other paths.
● LND #4715 adds a
parameter that will remove all onchain transactions from LND’s wallet
and then start a rescan of the block chain to repopulate the wallet.
● BOLTs #808 adds a warning that nodes must not release their own
HTLC preimages unless they’re the final receiver of a payment. This
warning may help new implementations avoid the premature release of preimages which caused
CVE-2020-26896 (see Newsletter #121).