Yes that's a real issue. In the context of multi-party protocols, you may
pre-signed transactions with the feerate of _today_ and then only going to
be broadcast later with a feerate of _tomorrow_.
In that case the pre-signed feerate may be so low that the transaction
I think this is a worthy idea as the funding outpoint of any off-chain
protocols is an invariant known by participants. Thus by sponsoring an
outpoint you're requiring from network mempools to increase the feerate of
the package locally known without assuming about the concrete state as any
Right, I was off the shot. Thanks for the explanation.
As you mentioned, if the goal of the sponsor mechanism is to let any party
drive a state N's first tx to completion, you still have the issue of
concurrent states being pinned and thus non-observable for sponsoring by an
EDIT: I misunderstood the emplacement of the sponsor vector, please
disregard previous review :( Beyond where the convenient place should live,
which is still accurate I think.
> Sponsor Vector TXIDs must also be
> in the block the transaction is validated in, with no restriction on
This is a really interesting proposal to widen the scope of fee mechanisms.
First, a wider point on what this proposal brings with regards to pinning,
to the best of my knowledge.
A pinning may have different vectors by exploiting a) mempools limits (e.g
descendants) or b) mempools
I think one of the general problems for any participant in an
interdependent chain of contracts like Lightning or CoinSwap is to avoid a
disequilibrium in its local HTLC ledger. Concretely sending forward more
than you receive backward. W.r.t, timelocks delta aim to enforce order of
I forgot to underscore that contract transaction output must be grieved by
at least a CSV of 1. Otherwise, a malicious counterparty can occupy with
garbage both the timelock-or-preimage output and its own anchor output thus
blocking you to use the bumping capability of your own anchor
I think you might have vulnerability issues with the current design.
With regards to the fee model for contract transactions, AFAICT timely
confirmation is a fund safety matter for an intermediate hop. Between the
offchain preimage reveal phase and the offchain private key handover
Security and operations of higher-layer protocols (vaults, LN, CoinJoin,
watchtowers, ...) come with different assumptions and demands with regards
to tx-relay and fee models. As the Bitcoin stack is quite young, it would
be great to make those ones more understood and what p2p/mempool
(tl;dr Ideally network mempools should be an efficient marketplace leading
to discovery of best-feerate blockspace demand by miners. It's not due to
current anti-DoS rules assumptions and it's quite harmful for shared-utxo
protocols like LN)
Lightning security model relies on the
> I have not studied the proposal in close detail yet, but anyway, my main
takeaway roughly is:
> * The core of CoinPool is some kind of multiparticipant (N > 2) offchain
update mechanism (Decker-Wattenhofer or Decker-Russell-Osuntokun).
> * The output at each state of the update
For the records, I didn't know between Greg and you was at the origin of
payment pools. Thanks for your pioneer work here, obviously this draws
inspiration from OP_CTV use cases and Channel Factories works, even if we
picked up different assumptions and tried to address another set of
We (Gleb Naumenko + I) think that a wide range of second-layer protocols
(LN, vaults, inheritance, etc) will be used by average Bitcoin users. We
are interested in finding and addressing the privacy issues coming from the
unique fingerprints these protocols bring.
More specifically, we
Well your deeclipser is already WIP ;)
See my AltNet+Watchdog proposals in Core:
It's almost covering what you mention, a driver framework to plug
alternative transports protocols : radio,
> (Of note as well, is that the onchain contract provided by such services
is the same in spirit as those instantiated in channels of the Lightning
Network, thus the same attack schema works on the onchain side.)
If you onchain contract uses a timelock and has concurrent
> * At the same time, it retains your-keys-your-coins noncustodiality,
because every update of a Lightning channel requires your keys to sign off
Yes I agree, I can foresee an easier step where managing low-value channel
and get your familiar with smooth key management maybe a first step
> > On Tue, May 5, 2020 at 9:01 PM Luke Dashjr via bitcoin-dev <
> > email@example.com> wrote:
> >> On Tuesday 05 May 2020 10:17:37 Antoine Riard via bitcoin-dev wrote:
> >>> Trust-minimization of Bitcoin security
Thanks for Blockchain Commons and Learning Bitcoin from the Command Line!
> If there are people interested in coordinating some proposals on how to
defining different sets of wallet functionality, Blockchain Commons would
be interested in hosting that collaboration. This could
Thanks for sharing about what it's technically possible to do for a
full-node on phone, specially with regards to lower grade devices.
I do see 2 limitations for sleeping nodes:
- a lightning specific one, i.e you need to process block data real-time in
case of incoming HTLC you need to
may have multiples options:
>> * halt the wallet, wait for human intervention
>> * fallback connection to a trusted server, authoritative on your chain
>> * invalidity proofs?
>> Now I agree you need a wide-enough, sane backbone network to build on
> As a result, the entire protocol could be served over something like
HTTP, taking advantage of all the established CDNs and anycast serving
Yes it's moving the issue of being a computation one to a distribution one.
But still you need the bandwidth capacities. What I'm concerned
> The choice between whether we offer them a light client technology that
is better or worse for privacy and scalability.
And offer them a solution which would scale in the long-term.
Again it's not an argumentation against BIP 157 protocol in itself, the
problem I'm interested in is how
foster node adoption as much as we can.
Le mar. 5 mai 2020 à 09:01, Luke Dashjr a écrit :
> On Tuesday 05 May 2020 10:17:37 Antoine Riard via bitcoin-dev wrote:
> > Trust-minimization of Bitcoin security model has always relied first and
> > above on running a full-node. This curre
I didn't trust myself and verify. In fact the  is the real .
Le mar. 5 mai 2020 à 06:28, Andrés G. Aragoneses a
> Hey Antoine, just a small note,  is missing in your footnotes, can you
> add it? Thanks
> On Tue, 5 May 2020 at 18:17, Antoine Riard
(cross-posting as it's really both layers concerned)
Ongoing advancement of BIP 157 implementation in Core maybe the opportunity
to reflect on the future of light client protocols and use this knowledge
to make better-informed decisions about what kind of infrastructure is
needed to support
> In that case, would it be worth re-implementing something like a BIP61
reject message but with an extension that returns the txids of any
That's an interesting idea, but an attacker can create a local conflict in
and then send the preimage tx to make hit recentRejects
Personally, I would have wait a bit before to go public on this, like
letting some implementations
increasing their CLTV deltas, but anyway, it's here now.
Mempool-pinning attacks were already discussed on this list , but what
we found is you
can _reverse_ the scenario, where it's not the
> I proposed before to consider splicing as a form of merged closing plus
funding, rather than a modification of channel state; in particular we
might note that, for compatibility with our existing system, a spliced
channel would have to change its short channel ID > and channel
> I notice your post puts little spotlight on unilateral cases.
> A thing to note, is that we only use `nSequence` and the weird watermark
on unilateral closes.
> Even HTLCs only exist on unilateral closes --- on mutual closes we wait
for HTLCs to settle one way or the other before doing the
chnorr happen we don't
have to wait another period to start enjoying the privacy enhancement
(worst-case we can fallback on 2p-ecdsa).
Le sam. 22 févr. 2020 à 07:10, AdamISZ a écrit :
> ‐‐‐ Original Message ‐‐‐
> On Friday, 21 February 2020 22:17, Antoine Riard via bitcoin-dev <
Coinjoins interceptions seem to raise at an increasing pace. Their onchain
fingerprint (high-number of inputs/outputs, lack of anti-fee snipping,
type, ...) makes their detection quite easy for a chain observer. A ban of
coinjoin'ed coins or any other coins linked through a common ownwer
> In particular, you care more about privacy when you are contesting a
> close of a channel or other script path because then the miners could be
> likely to extract a rent from you as "ransom" for properly closing your
> (or in other words, in a contested close the value of the
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