On 08/08/2016 01:42 PM, Gregory Maxwell wrote:
On Mon, Aug 8, 2016 at 5:09 PM, Andy Schroder via bitcoin-dev <[email protected]> wrote:I have mixed feelings about strictly tying the identity-public-keys with a[...]guaranteed static IP address. The second reason is because the DNS PTRI don't see any reason that it couldn't also accept a DNS name there.The purpose of that table is so the client knows which server ID to expect.
Okay, that may be fine. You are saying otherwise you'd have to do a trial and error and this tying to a network identifier just speeds things up? If the DNS is spoofed, it's no big deal because the authentication will fail anyway?
I consider it a good thing from a privacy perspective if my IP address changes every once and a while.And the design seeks to preserve that privacy.Maybe a strict check option where the identity-public-keys must optionally match a specific network identifier would be a compromise? Maybe this is upThe client must know the identity of the server it is expecting. The server does not announce itself. If it did then your changing of IPs would provide you with no privacy at all.
Good point.
If the design is to provide any protection against MITM you need to know who you expected to connect to in any case.I think the purpose of this is to detect if someone has physically stolen and compromised my bitcoin node and placed it on another network under control of an attacker.Huh. No. Almost the opposite. The system is designed to inhibit fingerprinting. You can't tell what identity key(s) a node has unless you already know them. This means that if you don't publish your node pubkey, no one can use it to track your node around the network.
Cool.
Is there an option for a wildcard here? Couldn't there be a case where the client wants to authenticate, but the bitcoin node does not care who it's clients are? This would be similar to many of the http based bitcoin block explorer API services that are out there. The API operators have built up some reputation, so people use them, but they don't necessarily care about who their users are.Then they're just not listed in the file. The client can ask the server to authenticate without authenticating itself.
Simple enough.
Does openssh have this same problem?No. OpenSSH doesn't make an effort to protect the privacy of its users.I'm assuming this could be parallelized very easily, so it is not a huge problem?It's not a issue because we're not aware of any usecase where a node would have a large list of authenticated peers.Each peer can configure one identity-key (ECC, 32 bytes) per listeningnetwork interface (IPv4, IPv6, tor). I'm not aware of any reason for this limitation to exist. A node should be able to have as many listening identities as it wants, with a similar cost to having a large authorized keys list.
So you are saying that you agree with me that the original text needs to be revised slightly or I am just misinterpreting the original text?
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