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I don't know exactly how Namecoin works, but I assume it's pretty similar to Bitcoin in that all clients must agree on which transactions are valid or invalid,

I don't know exactly how Namecoin works, but I assume it's pretty similar to Bitcoin in that all clients must agree on which transactions are valid or invalid, otherwise they risk forking the blockchain and disagreeing on which transactions are included. The problem I see with this proposal is each client needs to check the DNS record independently to ensure a transaction is valid. What happens if the DNS server happens to be unreachable or the owner accidentally or maliciously removes the signature in a DNS record after their transaction has been included in a block? Or maybe I'm misunderstanding things and Namecoin works differently?

DennisP 13y ago
No you're right, it's Bitcoin with a few extra transaction types. It seems like a pretty fundamental problem...Namecoin uses a system that enforces consistency, so you can't make it depend on a system that doesn't enforce consistency without breaking it.
itistoday2 13y ago
What happens if the DNS server happens to be unreachable or the owner accidentally or maliciously removes the signature in a DNS record after their transaction has been included in a block? If enough clients saw the transaction I don't see what the problem is. The domain owner would also be running a client after all, and they'd have the private keys to prove that they own the transaction. Once it makes it into the longest running blockchain with enough confirmations there's no reason to check the old DNS again (I don't think, unless I'm missing something). The next time the old DNS will need to be queried is when the domain expires. Maybe, by that point, no one will be relying on the previous system anymore. ;)
- DennisP 13y ago
  Let's say someone hacks a DNS server and adds the namecoin sig entry. They don't get it into root servers, but there's a population of namecoin users who see it. Hacker then issues a matching namecoin transaction registering that domain. So now one population of namecoin nodes sees the hacked entry, accepts the transaction, and puts it in a block. Another population doesn't see it and rejects the transaction. The blockchain forks. You might get by if the hacked DNS is seen by a minority of users. Then the chain without the disputed transaction will win anyway and all is well. But suppose most DNS nodes have the hacked entry? Then the minority will refuse to accept the majority chain, since they can't validate it, and the fork persists. If that seems implausible, imagine a hacker watching for a new DNS namecoin entry, and making his hacked DNS server immediately remove it. A few things would help a bit: - Only accept namecoin registrations when the matching DNS entry is old enough to have propagated everywhere - If the longest blockchain has old blocks that don't validate against DNS, keep checking. Hopefully the errant DNS servers will get fixed soon and that'll resolve the fork. - If the disputed block gets old enough, just go ahead and accept it if it's in the longest chain. You're just trying to minimize squatting, and letting some skilled squatters through isn't the worst disaster. But it's still kind of a mess because namecoin isn't just a naming system, it's also a currency. For as long as the fork persists, people can doublespend their coins. It'll be resolved but in the meantime maybe a merchant has shipped goods. You're essentially creating money that depends on the integrity of DNS for security.
  - cantfindmypass 13y ago
    As of right now, Namecoin doesn't look at data in DNS for validating transactions. This proposal involved hard-forking Namecoin, and has a lot of inherent issues with it. Also note that this proposal is by "some guy on a Namecoin forum", and not anything official.
    - itistoday2 13y ago
      Also note that this proposal is by "some guy on a Namecoin forum", and not anything official. And note that Bitcoin was a proposal by "some guy with a fake name."
    - DennisP 13y ago
      Yes, I was writing about the proposal the OP was about, not Namecoin as it exists today.
  - itistoday2 13y ago
    This was brought up in the forums, and here was the reply: Yes, this needs to be addressed. The proposal can be kept as-is with the following modification/addition: In order to prevent such attacks, it could be required that transactions need be confirmed across N "different networks", where "different networks" can be measured by some metric (IP2location, the first two octets of an IPv4 address, etc.). The value for N can be based as a percentage of the number of nodes running in the past 48 hours, or some other means. Copied from here: http://dot-bit.org/forum/viewtopic.php?p=7746#p7746 http://dot-bit.org/forum/viewtopic.php?p=7746#p7746
    - DennisP 13y ago
      Hm. I suppose if each node connects to a large number of DNS servers scattered around the internet, that would help a lot.
      - itistoday2 13y ago
        Yes, that's one way, although I think it would be safer for the verification to be done by other peers (on the answers provided by other peers), as opposed to peers doing it themselves by connecting to many DNS servers. The reason being the possibility that the traffic on a network is controlled entirely by an adversary, and thus all outgoing connections to port 53 (via UDP) could get routed to the same IP, regardless of what the destination IP actually is.
sliverstorm 13y ago
What happens if the DNS server happens to be unreachable This is not a problem with Namecoin, right? Traditional DNS has the exact same problem, namely general intolerance to failure.
- GigabyteCoin 13y ago
  Right. Mainly because everybody who runs a full namecoin node will have access to the equivalent of a root name server: http://en.wikipedia.org/wiki/Root_name_server http://en.wikipedia.org/wiki/Root_name_server
  - sargun 13y ago
    More like they will have access to the dot-bit TLD name servers.
- deleted 13y ago
  [deleted]
- tlrobinson 13y ago
  I don't think you understood my concern. The problem is if a signature stored in a legacy DNS record is used to verify a "registration" of a Namecoin domain, every Namecoin client needs to see the exact same "view" of that record, otherwise some Namecoin clients will consider it valid and some will consider it invalid, forking the Namecoin blockchain.
  - sliverstorm 13y ago
    You're right, I didn't pick up on that. Sorry.
cantfindmypass 13y ago
It is possible to delegate stuff to DNS (and some DNSSEC patches were recently merged - see http://dot-bit.org/forum/viewtopic.php?f=5&t=1434&p=7718 http://dot-bit.org/forum/viewtopic.php?f=5&t=1434&p=7718), but even if records are delegated to DNS namecoin doesn't know or care what's there. Namecoin is essentially a key-value store. A .bit domain is a key under Namecoin's d/ namespace, and the value is some JSON data describing the domain, per this spec: http://dot-bit.org/Namespace:Domain_names_v2.0 http://dot-bit.org/Namespace:Domain_names_v2.0 Edit: Actually, to further clarify, Namecoin itself doesn't know/care about the semantics of what data is stored for a domain. The data is interpreted by applications that act as application layer bridges to other resolver protocols. Check out nmcontrol and NamecoinToBind for examples.

DennisP 13y ago

No you're right, it's Bitcoin with a few extra transaction types. It seems like a pretty fundamental problem...Namecoin uses a system that enforces consistency, so you can't make it depend on a system that doesn't enforce consistency without breaking it.

itistoday2 13y ago

What happens if the DNS server happens to be unreachable or the owner accidentally or maliciously removes the signature in a DNS record after their transaction has been included in a block? If enough clients saw the transaction I don't see what the problem is. The domain owner would also be running a client after all, and they'd have the private keys to prove that they own the transaction. Once it makes it into the longest running blockchain with enough confirmations there's no reason to check the old DNS again (I don't think, unless I'm missing something). The next time the old DNS will need to be queried is when the domain expires. Maybe, by that point, no one will be relying on the previous system anymore. ;)

DennisP 13y ago
Let's say someone hacks a DNS server and adds the namecoin sig entry. They don't get it into root servers, but there's a population of namecoin users who see it. Hacker then issues a matching namecoin transaction registering that domain. So now one population of namecoin nodes sees the hacked entry, accepts the transaction, and puts it in a block. Another population doesn't see it and rejects the transaction. The blockchain forks. You might get by if the hacked DNS is seen by a minority of users. Then the chain without the disputed transaction will win anyway and all is well. But suppose most DNS nodes have the hacked entry? Then the minority will refuse to accept the majority chain, since they can't validate it, and the fork persists. If that seems implausible, imagine a hacker watching for a new DNS namecoin entry, and making his hacked DNS server immediately remove it. A few things would help a bit: - Only accept namecoin registrations when the matching DNS entry is old enough to have propagated everywhere - If the longest blockchain has old blocks that don't validate against DNS, keep checking. Hopefully the errant DNS servers will get fixed soon and that'll resolve the fork. - If the disputed block gets old enough, just go ahead and accept it if it's in the longest chain. You're just trying to minimize squatting, and letting some skilled squatters through isn't the worst disaster. But it's still kind of a mess because namecoin isn't just a naming system, it's also a currency. For as long as the fork persists, people can doublespend their coins. It'll be resolved but in the meantime maybe a merchant has shipped goods. You're essentially creating money that depends on the integrity of DNS for security.
- cantfindmypass 13y ago
  As of right now, Namecoin doesn't look at data in DNS for validating transactions. This proposal involved hard-forking Namecoin, and has a lot of inherent issues with it. Also note that this proposal is by "some guy on a Namecoin forum", and not anything official.
  - itistoday2 13y ago
    Also note that this proposal is by "some guy on a Namecoin forum", and not anything official. And note that Bitcoin was a proposal by "some guy with a fake name."
  - DennisP 13y ago
    Yes, I was writing about the proposal the OP was about, not Namecoin as it exists today.
- itistoday2 13y ago
  This was brought up in the forums, and here was the reply: Yes, this needs to be addressed. The proposal can be kept as-is with the following modification/addition: In order to prevent such attacks, it could be required that transactions need be confirmed across N "different networks", where "different networks" can be measured by some metric (IP2location, the first two octets of an IPv4 address, etc.). The value for N can be based as a percentage of the number of nodes running in the past 48 hours, or some other means. Copied from here: http://dot-bit.org/forum/viewtopic.php?p=7746#p7746 http://dot-bit.org/forum/viewtopic.php?p=7746#p7746
  - DennisP 13y ago
    Hm. I suppose if each node connects to a large number of DNS servers scattered around the internet, that would help a lot.
    - itistoday2 13y ago
      Yes, that's one way, although I think it would be safer for the verification to be done by other peers (on the answers provided by other peers), as opposed to peers doing it themselves by connecting to many DNS servers. The reason being the possibility that the traffic on a network is controlled entirely by an adversary, and thus all outgoing connections to port 53 (via UDP) could get routed to the same IP, regardless of what the destination IP actually is.

sliverstorm 13y ago

What happens if the DNS server happens to be unreachable This is not a problem with Namecoin, right? Traditional DNS has the exact same problem, namely general intolerance to failure.

GigabyteCoin 13y ago
Right. Mainly because everybody who runs a full namecoin node will have access to the equivalent of a root name server: http://en.wikipedia.org/wiki/Root_name_server http://en.wikipedia.org/wiki/Root_name_server
- sargun 13y ago
  More like they will have access to the dot-bit TLD name servers.
deleted 13y ago
[deleted]
tlrobinson 13y ago
I don't think you understood my concern. The problem is if a signature stored in a legacy DNS record is used to verify a "registration" of a Namecoin domain, every Namecoin client needs to see the exact same "view" of that record, otherwise some Namecoin clients will consider it valid and some will consider it invalid, forking the Namecoin blockchain.
- sliverstorm 13y ago
  You're right, I didn't pick up on that. Sorry.

cantfindmypass 13y ago

It is possible to delegate stuff to DNS (and some DNSSEC patches were recently merged - see http://dot-bit.org/forum/viewtopic.php?f=5&t=1434&p=7718 http://dot-bit.org/forum/viewtopic.php?f=5&t=1434&p=7718), but even if records are delegated to DNS namecoin doesn't know or care what's there. Namecoin is essentially a key-value store. A .bit domain is a key under Namecoin's d/ namespace, and the value is some JSON data describing the domain, per this spec: http://dot-bit.org/Namespace:Domain_names_v2.0 http://dot-bit.org/Namespace:Domain_names_v2.0 Edit: Actually, to further clarify, Namecoin itself doesn't know/care about the semantics of what data is stored for a domain. The data is interpreted by applications that act as application layer bridges to other resolver protocols. Check out nmcontrol and NamecoinToBind for examples.