Re: [Bitcoin-development] Roadmap to getting users onto SPV clients

[Gary Rowe <g.rowe@froot.co.uk>]

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I would like to chime on on the user experience of the SPV client (in
particular MultiBit).

Without exception, everyone that I have introduced Bitcoin (which is a lot
of people) have expected an "instant-on" experience. It has to clobber
PayPal and credit cards or people won't give it a second look, let alone a
second chance. SPV clients deliver on that expectation.

Once the user has the great initial "wow!" moment then their interest in
Bitcoin is reinforced and they tend to explore further, particularly into
the economic theory behind it. Many decide to install the full node out of
a sense of community contribution to the security of the network.

Having a hybrid mode of SPV first then full node second should be something
that a user has control over - it is their computing resources we are using
after all and Bitcoin should not be perceived as a drain.


On 5 December 2012 07:50, Wladimir <laanwj@gmail.com> wrote:

> Jim,
>
> Most of those issues don't have to do with the SPV versus non-SPV problem.
>
> First person doesn't understand what Bitcoin is supposed to do (he's
> confusing mining and running a node). An information problem that could be
> solved by explaining what is going on.
>
> Another one seems to have a problem with DEP. That's probably an issue
> with his OS configuration.
>
> The third one is confused about the fees. Again, an information problem.
>
> Only the fourth one is concerned with synchronization. The other ones
> could happen with any client, as they're either based on misconceptions
> about bitcoin as a whole or computer problems.
>
> This doesn't in any way make switching to another, reduced security model
> client preferable. Let's first try to improve the Bitcoin experience with
> full security model, and if that somehow turns out to be impossible it's
> always possible to recommend some other client based on the 'user type'.
>
> I don't agree that this point is now. Anyway, security and stability of
> the network is of utmost importance to do anything in the future, better to
> grow organically than explode.
>
> Many initiatives are underway to improve the Satoshi client (for
> example to have Bitcoin-Qt behave as SPV client during initial block
> download, and as full node after that), but as usual in open source
> development, many of us are doing this basically for fun in our free time
> it does not always go as fast as users would like.
>
> I wish there was a straightforward solution for that, yeah pooling
> together our development on one or two clients instead of a zillion
> different ones could help, but everyone has more fun working on their own
> client that's just how things go :)
>
> Wladimir
>
> On Wed, Dec 5, 2012 at 6:38 AM, Jim Nguyen <jimmy.winn@gmail.com> wrote:
>
>> Gavin's grandma needs to be able to use bitcoin.  Here is a real world
>> sampling of the types of people wanting to use bitcoin but are having some
>> difficulty which I have collected from Facebook.  Should we listen to the
>> end user? :-P
>>
>> *"what is the intention of Bitcoin? Is it supposed to be - eventually -
>> for dummies like myself or is it just for those individuals who are code
>> and algorithm writers? I downloaded a wallet but how do I know if I need
>> more software or a massive computer system to solve "the problem" for the
>> next block? With all the talk of mathematical problem solving on a world
>> wide network of computers I can't see a small laptop figuring out anything
>> thus not gaining any bitcoins. Why should I be interested in this if it
>> appears it's just for computer scientists?"*
>>
>> *"hi, instaled bitcoin qt, but after it dowladed all the stuff, now i
>> get DEP protecction from windows, and it tells me bitcoinQT need to run
>> with DEP on, dont let me make an exception for it, nor work it i turn DEP
>> only for sys, so hwat i should do?"*
>>
>> *"hi, i'm new to bitcoin, i got a bunch of free bitcoins from a bunch of
>> the free sites. how come when i tried to send my bitcoins to myself, it
>> says the fee exceeds the balance? I thought there was no fees?"*
>>
>> *"Is there a way to speed up the process of synchronisation with the
>> network? It has been taken ages on my MAC.*
>> *Any help would be nice"*
>> *
>> *
>> *and more...*
>>
>> Sorry if this doesn't belong to the bitcoin-development email list.  I
>> just see this as end-user/customer data gathering to refine the
>> requirements, since this is software engineering...isn't it?
>>
>> Jim
>>
>> On Tue, Dec 4, 2012 at 6:54 PM, Gregory Maxwell <gmaxwell@gmail.com>wrote:
>>
>>> On Tue, Dec 4, 2012 at 9:08 PM, Alan Reiner <etotheipi@gmail.com> wrote:
>>> > Our divergence is on two points (personal opinions):
>>> >
>>> > (1) I don't think there is any real risk to the centralization of the
>>> > network by promoting a SPV (purely-consuming) node to brand-new users.
>>> > In my opinion (but I'm not as familiar with the networking as you), as
>>> > long as all full nodes are full-validation, the bottleneck will be
>>> > computation and bandwidth, long before a constant 10k nodes would be
>>> > insufficient to support propagating data through the network.
>>>
>>> Not so— a moderately fast multicore desktop machine can keep up with
>>> the maximum possible validation rate of the Bitcoin network and the
>>> bandwidth has a long term maximum rate of about 14kbit/sec— though
>>> you'll want at least ten times that for convergence stability and the
>>> ability feed multiple peers.
>>>
>>> Here are the worst blocks testnet3 (which has some intentionally
>>> constructed maximum sized blocks),E31230 :
>>> (with the new parallel validation code)
>>> - Verify 2166 txins: 250.29ms (0.116ms/txin)
>>> - Verify 3386 txins: 1454.25ms (0.429ms/txin)
>>> - Verify 5801 txins: 575.46ms (0.099ms/txin)
>>> - Verify 6314 txins: 625.05ms (0.099ms/txin)
>>> Even the slowest one _validates_ at 400x realtime. (these measurements
>>> are probably a bit noisy— but the point is that its fast).
>>> (the connecting is fast too, but thats obvious with such a small
>>> database)
>>>
>>> Although I haven't tested leveldb+ultraprune with a really enormous
>>> txout set or generally with sustained maximum load— so there may be
>>> other gaffs in the software that get exposed with sustained load, but
>>> they'd all be correctable. Sounds like some interesting stuff to test
>>> with on testnet fork that has the POW test disabled.
>>>
>>> While syncing up a behind node can take a while— keep in mind that
>>> you're expecting to sync up weeks of network work in hours. Even
>>> 'slow' is quite fast.
>>>
>>> > In fact,
>>> > I was under the impression that "connectedness" was the real metric of
>>> > concern (and resilience of that connectedness to large percentage of
>>> > users disappearing suddenly).  If that's true, above a certain number
>>> of
>>> > nodes, the connectedness isn't really going to get any better (I know
>>> > it's not really that simple, but I feel like it is up to 10x the
>>> current
>>> > network size).
>>>
>>> Thats not generally concern for me. There are a number of DOS attack
>>> risks... But attacker linear DOS attacks aren't generally avoidable
>>> and they don't persist.
>>>
>>> Of the class of connectedness concerns I have is that a sybil attacker
>>> could spin up enormous numbers of nodes and then use them to partition
>>> large miners.  So, e.g. find BitTaco's node(s) and the nodes for
>>> miners covering 25% hashpower and get them into a separate partition
>>> from the rest of the network. Then they give double spends to that
>>> partition and use them to purchase an unlimited supply of digitally
>>> delivered tacos— allowing their captured miners to build an ill fated
>>> fork— and drop the partition once the goods are delivered.
>>>
>>> But there is no amount of full nodes that removes this concern,
>>> especially if you allow for attackers which have compromised ISPs.
>>> It can be adequately addressed by a healthy darknet of private
>>> authenticated peerings between miners and other likely targets. I've
>>> also thrown out some ideas on using merged mined node IDs to make some
>>> kinds of sybil attacks harder ... but it'll be interesting to see how
>>> the deployment of ASICs influences the concentration of hashpower— it
>>> seems like there has already been a substantial move away from the
>>> largest pools. Less hashpower consolidation makes attacks like this
>>> less worrisome.
>>>
>>> > (2) I think the current experience *is* really poor.
>>>
>>> Yes, I said so specifically.  But the fact that people are flapping
>>> their lips here instead of testing the bitcoin-qt git master which is
>>> an 1-2 order of magnitude improvement suggests that perhaps I'm wrong
>>> about that.  Certainly the dearth of people testing and making bug
>>> reports suggests people don't actually care that much.
>>>
>>> > You seem to
>>> > suggest that the question for these new users is whether they will use
>>> > full-node-or-lite-node, but I believe it will be a decision between
>>> > lite-node-or-nothing-at-all (losing interest altogether).
>>>
>>> No. The "question" that I'm concerned with is do we promote lite nodes
>>> as equally good option— even for high end systems— remove the
>>> incentive for people to create, improve, and adopt more useful full
>>> node software and forever degrade the security of the system.
>>>
>>> > Waiting a day
>>> > for the full node to synchronize, and then run into issues like
>>> > blkindex.dat corruption when their system crashes for some unrelated
>>> > reason and they have to resync for another day... they'll be gone in a
>>> > heartbeat.
>>>
>>> The current software patches plus parallelism can sync on a fast
>>> system with luck network access (or a local copy of the data) in under
>>> an hour.
>>>
>>> This is no replacement for start as SPV, but nor are handicapped
>>> client programs a replacement for making fully capable ones acceptably
>>> performing.
>>>
>>> > Users need to experience, as quickly and easily as possible, that they
>>> > can move money across the world, without signing up for anything or
>>> > paying any fees.
>>>
>>> Making the all the software painless for users is a great goal— and
>>> one I share.  I still maintain that it has nothing to do with
>>> promoting less capable and secure software to users.
>>>
>>>
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>>
>>
>>
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