Previous to this change taproot assets channels and simple taproot channels were
considered the same in the context of chanbackup package, since they stored the
same data. In the following commits we are adding the data needed to produce a
signed commitment transaction from a SCB file and in order to do that we need to
add more fields and a custom channel gets one additional field (TapscriptRoot)
compared to a simple taproot channel. So now we have to distinguish these kinds
of channels in chanbackup package.
See PR https://github.com/lightningnetwork/lnd/pull/8183 for more details.
The functions inside of the crypto.go file in chanbackup (like EncryptPayloadToWriter and DecryptPayloadFromReader) can be used by a lot of things outside of just the chanbackup package. We can't just reference them directly from the chanbackup package because it's likely that it would generate circular dependencies. Therefore we need to move these functions into their own package to be referenced by chanbackup and whatever new functionality that needs them
This introduces a BigSize migration that is used to expand the width
of the ChannelStatus and ChannelType fields. Three channel "types"
are added - ZeroConfBit, ScidAliasChanBit, and ScidAliasFeatureBit.
ScidAliasChanBit denotes that the scid-alias channel type was
negotiated for the channel. ScidAliasFeatureBit denotes that the
scid-alias feature bit was negotiated during the *lifetime* of the
channel. Several helper functions on the OpenChannel struct are
exposed to aid callers from different packages.
The RefreshShortChanID has been renamed to Refresh.
A new function BroadcastHeight is used to guard access to the
mutable FundingBroadcastHeight member. This prevents data races.
This commit was previously split into the following parts to ease
review:
- 2d746f68: replace imports
- 4008f0fd: use ecdsa.Signature
- 849e33d1: remove btcec.S256()
- b8f6ebbd: use v2 library correctly
- fa80bca9: bump go modules
This commit changes the WriteElement and WriteElements methods to take a
write buffer instead of io.Writer. The corresponding Encode methods are
changed to use the write buffer.
This commit adds a RevocationKeyLocator field to the OpenChannel
struct so that the SCB derivation doesn't have to brute-force the
sha chain root key and match the public key. ECDH derivation is now
used to derive the key instead of regular private key derivation a
la DerivePrivKey. The legacy can still be used to recover old
channels.
In this commit, we create a new Single version for channels that use the
tweakless commitment scheme. When recovering from an SCB into an open
channel shell, we'll now check this field and use it to determine the
proper channel type. Otherwise, we may attempt to sweep the on chain
funds using the commitment point, when it goes directly to our key, or
the other way around.
In this commit, we extend the prior Single format to include the entire
channel config, other than the constraints, but including the CSV delay
for both sides. We do this as we'll need more of the keying information
in order to properly execute the DLP protocol. Additionally, in the
future, if warranted, this would allow channels to be resumed if deemed
safe.
In this commit, we add the initial implementation of the SCB structure.
Given an SCB, and a user's seed, it will be possible to recover the
settled balanced of a channel in the event of total or partial data
loss. The SCB contains all information required to initiate the data
loss protection protocol once we restore the channel and connect to the
remote channel peer.
The primary way outside callers will interact with this package are via
the Pack and Unpack methods. Packing means writing a
serialized+encrypted version of the SCB to an io.Writer. Unpacking does
the opposite.
The encoding format itself uses the same encoding as we do on the wire
within Lightning. Each encoded backup begins with a version so we can
easily add or modify the serialization format in the future, if new
channel types appear, or we need to add/remove fields.
