Re: [bitcoin-dev] Drivechain RfD -- Follow Up

[Paul Sztorc <truthcoin@gmail.com>]

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I will repeat that Drivechain can sometimes be confusing because it is
different things to different people.

Here is my attempt to break it down into different modes:

[DC#0] -- Someone who does not upgrade their Bitcoin software (and is
running, say, 0.13). However, they experience the effects of the new
rules which miners add (as per the soft fork[s] to add drivechain
functionality and individual drivechains).
[DC#1] -- Someone who always upgrades to the latest version of the
Bitcoin software, but otherwise has no interest in running/using sidechains.
[DC#2] -- Someone who upgrades to the latest Bitcoin version, and
decides to also become a full node of one or more sidechains, but who
ever actually uses the sidechains.
[DC#3] -- Someone who upgrades their software, runs sidechain full
nodes, and actively moves money to and from these.

Greg is still conflating modes [DC#1] and [DC#3]. Specifically, he
equivocates on the team "steal", using it to mean two different things:
[a] spending an invalid transaction, and [b] a withdrawal that would not
match the report given by a sidechain node.

The two are quite different, see my comments below:


On 7/12/2017 9:15 PM, Tao Effect wrote:
>> FYI that document is nearly two years old, and although it is still
>> overwhelmingly accurate, new optimizations allow us (I think) to push
>> the waiting period to several weeks and the total ACK counting period
>> up to several months.
> What does that have to do with my question? The counting period, if I
> understood correctly, is something miners do, not full nodes.

Greg quoted a passage that contained an older parameter estimate of "a
few days", and I thought it would be helpful and informative if I
clarified that the parameter estimate had been updated to a new (more
secure) value.

In point of fact, he is wrong, because nodes do the counting. When
miners find a block, they can choose to move the counter up, down, or
not at all. But nodes do the counting.


> Also, if the document is old and/or outdated, do you happen to have a
> link to a more update-to-date version of the spec? It would be helpful
> for review.

As I stated above, the document is mostly accurate. There is no other
more up to date version.


>> Because if a node doesn't have the sidechain's information, it will
>> just assume every withdrawal is valid. This is comparable to someone
>> who still hasn't upgraded to support P2SH, in cases [DC#0] and [#1].
>
> Right, for [DC#0] and [DC#1], but for [DC#2] an [DC#3] you marked it
> as "Yes" without substantiating why you did so.


Above, Greg omitted his original question. For reference, it was:

>  The Drivechain spec seems to claim that its use of anyone-can-pay is the same as P2SH

The answer is that both DC and P2SH use transactions which are 'always
valid' to some group of people (un-upgraded users) but which are
sometimes invalid to new users. So the only difference would be for
[DC#0] vs other versions, but this difference is trivial as miners will
censor invalid txns.

It is your classic soft fork situation.


>> Again, from the perspective of a mainchain user, every withdrawal is
>> valid.
> And that is not how P2SH works.

Again, keep in mind that Greg continually conflates two different things:
1. Whether the soft fork rules have been followed, and
2. Whether the WT^ submitted by a majority hashrate matches the one
calculated by sidechain nodes.

The first case is exactly equal to P2SH. Just as old nodes accept every
P2SH transaction, so too will [DC#0] users accept every WT^ transaction.

In the second case, it so happens that [DC#1], [DC#2], and [DC#3] would
also accept any WT^ *that followed the Drivechain rules*, even if they
did not like the outcome (because the outcome in question was
arbitrarily designated as a "theft" of funds -- again, see the second
case in the list above). In this way, it is exactly similar to P2SH
because nodes will accept *any* p2sh txn **that follows the p2sh
rules**, even if they don't "like" the specific script contained within
(for example, because it is a theft of "their" BitFinex funds, or a
donation to a political candidate they dislike, etc).


>> [DC#2] and [DC#3] would certainly have an interest in understanding
>> what is going on, but that has absolutely nothing whatsoever to do
>> with Bitcoin Core and so is off-topic for this mailing list.
> How is that an answer to my question?

Greg is, of course, not entitled to an answer to irrelevant questions --
just as he would not be entitled to an answer if he asked for my
favorite color or my home address. And such answers would needlessly
consume the mailing list's scarce time.


> What does "[DC#2] and [DC#3] would certainly have an interest in
> understanding what is going on" mean?

It is clear to me that, if we are not clear on the basics first, we
cannot hope to tackle anything intermediate. We will come back to this
after clearing up soft fork part.


> In P2SH, all upgraded nodes will reject invalid P2SH transactions, period.

In DC, all upgraded nodes will reject invalid DC transactions, period.


> What exactly would [DC#2] and [DC#3] nodes do when faced with an
> invalid WT^ transaction — invalid in the sense that it contains funds
> which miners are stealing?

The [DC#2] and [DC#3] nodes would do exactly what the [DC#0] and [DC#1]
nodes do. This is what I mean by "every withdrawal is valid".


> Again, in P2SH miners cannot steal funds, because all full nodes have
> a fully automatic enforcement policy.

In DC, miners cannot steal funds, because all full nodes have a fully
automatic enforcement policy.

However, DC *allows* users to choose to place some of their BTC at the
relative mercy of the miners in creative ways, if they wish (as does
P2SH -- someone could write a script which donates funds to miners, and
then fund it... "paying" to that script). This is another example of
conflating [DC#1] and [DC#3].

Paul



>> On Jul 12, 2017, at 5:26 PM, Paul Sztorc <truthcoin@gmail.com
>> <mailto:truthcoin@gmail.com>> wrote:
>>
>> The confusion below stems from his conflation of several different ideas.
>>
>> I will try to explicitly clarify a distinction between several types
>> of user (or, "modes" of use if you prefer):
>>
>> [DC#0] -- Someone who does not upgrade their Bitcoin software (and is
>> running, say, 0.13). However, they experience the effects of the new
>> rules which miners add (as per the soft fork[s] to add drivechain
>> functionality and individual drivechains).
>> [DC#1] -- Someone who always upgrades to the latest version of the
>> Bitcoin software, but otherwise has no interest in running/using
>> sidechains.
>> [DC#2] -- Someone who upgrades to the latest Bitcoin version, and
>> decides to also become a full node of one or more sidechains, but who
>> ever actually uses the sidechains.
>> [DC#3] -- Someone who upgrades their software, runs sidechain full
>> nodes, and actively moves money to and from these.
>>
>>
>> On 7/12/2017 6:43 PM, Tao Effect wrote:
>>>
>>> I am now looking closer again at step number 4 in the Drivechain
>>> specification [2]:
>>>
>>>     4. Everyone waits for a period of, say, 3 days. This gives
>>>     everyone an opportunity to make sure the same WT^ is in both the
>>>     Bitcoin coinbase and the Sidechain header. If they’re different,
>>>     everyone has plenty of time to contact each other, figure out
>>>     what is going on, and restart the process until its right.
>>>
>>> It seems to me that where our disagreement lies is in this point.
>>> The Drivechain spec seems to claim that its use of anyone-can-pay is
>>> the same as P2SH (and in later emails you reference SegWit as well).
>>> Is this really true?
>> FYI that document is nearly two years old, and although it is still
>> overwhelmingly accurate, new optimizations allow us (I think) to push
>> the waiting period to several weeks and the total ACK counting period
>> up to several months.
>>
>> [DC#0] Yes
>> [DC#1] Yes
>> [DC#2] Yes
>> [DC#3] Yes
>>
>> Because if a node doesn't have the sidechain's information, it will
>> just assume every withdrawal is valid. This is comparable to someone
>> who still hasn't upgraded to support P2SH, in cases [DC#0] and [#1].
>>
>> (And this is the main advantage of DC over extension blocks).
>>
>>
>>> 2. Per the question in [1], it's my understanding that P2SH
>>> transactions contain all of the information within themselves for
>>> full nodes to act as a check on miners mishandling the
>>> anyone-can-spend nature of P2SH transactions. However, that does not
>>> seem to be the case with WT^ transactions.
>> [DC#0] They do.
>> [DC#1] They do.
>> [DC#2] They do.
>> [DC#3] They do.
>>
>> Again, from the perspective of a mainchain user, every withdrawal is
>> valid.
>>
>>
>>> In P2SH txns, there is no need for anyone to, as the Drivechain spec
>>> says, "to contact each other, figure out what is going on".
>>> Everything just automatically works.
>> There is no *need* to this in Drivechain, either, for [DC#0] or [DC#1].
>>
>> [DC#2] and [DC#3] would certainly have an interest in understanding
>> what is going on, but that has absolutely nothing whatsoever to do
>> with Bitcoin Core and so is off-topic for this mailing list.
>>
>>
>>> If the security of WT^ transactions could be brought up to actually
>>> be in line with the security of P2SH and SegWit transactions, then I
>>> would have far less to object to.
>> Somehow I doubt it.
>>
>>
>> Paul
>


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