Re: [bitcoin-dev] Proposal: extend bip70 with OpenAlias

[Justin Newton <justin@netki.com>]

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[continued]



> 3> We use a 2 tier lookup format.  The first lookup returns a list of
>> currencies or payment types supported by the Wallet Name.  The second
>> lookup goes to a record specific to that currency type to get the
>> address to go to.  We believe this to be a more scalable solution in a
>> world where someone can have both multiple digital currency types, but
>> then also multiple types of colored coins, and wants a simple way to
>> share a single name for all of those different addresses.  This allows
>> the wallet to do the work behind the scene of choosing the currency it
>> wants to send, and automatically getting back the right address to
>> send to, without the user having to do anything different.
>>
>
> We do the same thing, except in a single call. Here's an example of a
> record that has both XMR and BTC addresses:
> https://api.openalias.org/donate.getmonero.org?view=full (here are the
> DNS records for that:
> http://mxtoolbox.com/SuperTool.aspx?action=txt%3adonate.getmonero.org&run=toolpage
> )
>


We looked at doing this in a single lookup as you did.  With one or two
currencies this can be potentially more efficient.  As the number of
supported currencies and addresses under a single name grows, however, this
solution becomes potentially more problematic.  Please follow the use cases
below:

Use case 1:  Wallet Name = "bob.foo.bar" or OpenAlias = "bob.foo.bar"

The only currency supported is bitcoin, and there are no colored coin
formats supported.

OpenAlias case:

1 packet lookup to "bob.foo.bar"
1 packet response with bitcoin address

= 2 packets


Wallet Name case:

1 packet lookup to "_wallet.bob.foo.bar"
1 packet response with supported address types
1 packet lookup to "_btc._wallet.bob.foo.bar"
1 packet response with bitcoin address

= 4 packets

Wallet Name Case 1a:

The wallet doing the lookup knows it wants bitcoin, so it skips the
supported addresses lookup

1 packet lookup to "_btc._wallet.bob.foo.bar"
1 packet response with bitcoin address

= 2 packets

In this use case we might create more traffic, but it could also be reduced
by doing smart lookups.


Use case 2:  Wallet Name = "bob.foo.bar" or OpenAlias = "bob.foo.bar"

Many currencies and colored coin addresses are supported under the same
name, lets say 100.  When you count different currencies and colored coin
types, it could easily be hundreds, or over a thousand.


OpenAlias case:

1 packet lookup to "bob.foo.bar"
100 packet responses with various addresses

= 101 packets


Wallet Name case:

1 packet lookup to "_wallet.bob.foo.bar"
1 packet response with supported address types
1 packet lookup to "_btc._wallet.bob.foo.bar"
1 packet response with bitcoin address

= 4 packets

Wallet Name Case 2a:

The wallet doing the lookup knows it wants bitcoin, so it skips the
supported addresses lookup

1 packet lookup to "_btc._wallet.bob.foo.bar"
1 packet response with bitcoin address

= 2 packets


While you may end doing "less lookups" under Open Alias, as it scales, you
end up causing a significant amount of extra, unnecessary traffic.

In addition to the obvious impact of being orders of magnitude more
wasteful than necessary, it also creates privacy "leakage" by returning
someone 100 different addresses when they only asked for one.

Finally, because a single packet UDP transaction for a DNS lookup can
create possibly hundreds of packets in response, the service can
essentially become an amplifier for DDoS attacks.  (If I spoof the source
address of my target with a query to a lookup that issues hundreds of
packets in response to one packet, and I can have a real impact :( )




>
>
>> 4> We mandate DNSSEC while you make it optional.  We did this because
>> we believe giving the user the option of NOT using DNSSEC is like
>> letting them order a car with no brakes.  We weren't sure how we would
>> explain to them why their money was gone when they really didn't
>> understand the risks they were taking up front. We had a lot of
>> discussion about it before coming to the decision we did, and I can
>> see why you went the other way, although I do believe we made the
>> right choice.
>>
>
> With OpenAlias a DNSSEC fail is a soft fail, and the user has to confirm
> the address. The reasons are threefold:
>
> 1. At the moment only 83.5% of the TLDs are signed [2]. The unsigned ones
> include some biggies like .sg, .za, and .to
>

I think this is a good point, and one we weighed.  When we were making our
original decisions.  Given the importance of ensuring that the lookups
return the correct value, and the known vulnerabilities in DNS without
DNSSEC, coupled with the fact that ICANN has mandated all zones and
registries move to DNSSEC, our belief was and is that it was worth the
trade off that there were cases where existing domains would not work.


It is important to note, that ICANN has "required" for some years that
registrars and registries support DNSSEC on the domains they register.  I
personally believe we shouldn't delay use of DNSSEC until their registries
had come up to current required Internet standards.  (Here are ICANN's
registrar requirements showing the DNSSEC requirement, btw:
https://www.icann.org/resources/pages/approved-with-specs-2013-09-17-en#operation
)

That said, what do others in the industry think?  We are basing our current
standard on our believed best practices, and defaulted to "first, lose no
money", given the irreversibility of bitcoin.



> 2. Even if the zone *is* signed, DNSSEC deployment is hard. Unmanaged
> DNSSEC deployment is out of scope for probably 99.9% of users, even the
> usually-technically-ok Bitcoin crowd. Managed DNSSEC is available, but is
> quite pricey. UltraDNS, Dyn, and GoDaddy (ikr?) are the three big
> providers, and of those three only GoDaddy has a consumer-affordable
> product.
>


I think "DNSSEC is hard" is a bit of a boogey man that's not really true.
We are working on developing registrar by registrar instructions of how to
do this, and we have typically found that if you are setting up DNS by
yourself, adding DNSSEC doesn't take a lot of additional time, maybe an
hour or so depending on your registrar.

This known concern, however, is why when we launched our product (based on
our standard record formats) that we wanted to launch it with a variety of
options for people.

In addition to these options there are also other hosting providers, and
certain registrars that will allow you to setup DNSSEC on their DNS
platforms.


1> One could choose the "0 click" installation process of just getting a
free Wallet Name underneath their provider's name space.  This option has
been free to end users in all cases so far, and I expect it always will be
in the future (although that is up to the partner, so some may choose to
charge).

2> If they wanted some provider independence, but someone to manage things
for them, they can register a name through us and manage everything via our
web interface.  This can cost them as little as $1.95/yr through us.

3> Finally, for the "do it yourselfer" who wants full control themselves,
they can simply follow the formats on our developer page and do the whole
thing themselves.  If they do this by registering their own ".bit" this
will cost them less than $0.25.  If they have an existing domain name, even
less.






>
> 3. ThomasV and I have done a stack of testing behind residential and
> commercial routers where DNSSEC simply fails (eg. the router runs a really
> outdated DNS server that doesn't provide RRSIGs in its response, or the ISP
> doesn't care about DNSSEC). Unsurprisingly, this can be fixed by...you
> guessed it...doing the lookup via DNSCrypt.
>

That's some interesting data, and runs counter to the research of the IETF
DNS working group.  If you are willing to share your data, I can put you in
touch with the appropriate folks there to share your research.  I'd also
love to see it!



>
> Until we are closer to the bulk of all TLDs being signed, and DNSSEC
> becomes at least a little more ubiquitous, we can't lock out huge portions
> of the Internet, because then we're not really providing a useful and
> usable solution. All we can is make it more difficult to pay an unverified
> domain.
>
> Of course, if your aim is to force people to use you as a domain
> registrar, then it makes total sense why you'd lock people out;)
>

I'd argue that we aren't locking "huge portions" of the Internet.  You are
correct that about 15% of TLD's are not yet signed, even though they were
required to be by ICANN.

As I said above, I believe the requirement to not lose money and the fact
that other options are available for those running on TLD's that are out of
compliance, is worth the trade off that some existing names won't work
until their TLD's come into compliance with current Internet standards.

And, as we covered above, we don't force anyone to use our registrar, nor
any of our services in order for Wallet Names to work for them.  We never
have.  It's just not who we are.

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