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Magic-Wormhole – Get things from one computer to another, safely

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Re: Magic-Wormhole – Get things from one computer to another, safely

#52
post #37
post #12

Earlier quoted context omitted.

Any attacker only gets a single guess

What if there are 65535 active send requests? Perhaps of which 65534 are opened by an attacker?

Probably all "slots" would be "occupied" and everybody gets the attacker's sent file, iiuc.

Re: Magic-Wormhole – Get things from one computer to another, safely

#53
post #46
post #37

Earlier quoted context omitted.

What if there are 65535 active send requests? Perhaps of which 65534 are opened by an attacker?

The attacker still just gets 1 guess per wormhole / send request. Each send-request / wormhole is its own separate thing.

I'm still unclear on a couple of things. How do you even know which send request the attacker attempted to attack if only the codeword identifies the send request, and the codeword was wrong? Also, what stops an attacker from trying again - alternatively, what stops an attacker from doing a denial-of-service by purposefully guessing the wrong codeword?

Re: Magic-Wormhole – Get things from one computer to another, safely

#54
post #5

This reminds me of the great tool http://www.fefe.de/ncp/ , which seems like the same thing only without the cryptographic authentication!

Nifty.. I'll look at the network side of that, maybe we can steal some ideas. At the moment magic-wormhole depends upon one of: * at least one side has a public IP address * both sides are on the same (private) LAN * a TURN-like "Transit Relay" server that I run That transit server hasn't gotten a worrysome amount of traffic yet, but it's a potential scaling problem. (Fortunately the two sides can offer their own tra…

Uh... just an idea: can you leverage the cloud flare infra challenge for the transit server piece?

Re: Magic-Wormhole – Get things from one computer to another, safely

#55
post #34

How does this compare to AirDrop (besides obviously being cross platform)?

AirDrop: waaaay better UI, awesome animated drag-and-drop, dead-simple to use, works offline. Not so strong at clearly identifying who the file came from or is going to. Not clear what sort of integrity/confidentiality properties you get (probably better than nothing, knowing Apple, but since the send-to-which-device picker UI shows their self-selected names, there's not any obvious way to distinguish between the real "Alice's iPhone" sitting next to you and the attacker who's within bluetooth range.

Magic-Wormhole: CLI only (so far), no OS integration anywhere, better security properties. Also it's got a spiffy wizard-hat logo (thanks Katie!).

Re: Magic-Wormhole – Get things from one computer to another, safely

#56
post #37

Earlier quoted context omitted.

What if there are 65535 active send requests? Perhaps of which 65534 are opened by an attacker?

Probably all "slots" would be "occupied" and everybody gets the attacker's sent file, iiuc.

Or the attacker only needs to monitor the last free slot to see what shows up?

Re: Magic-Wormhole – Get things from one computer to another, safely

#58
post #56

Earlier quoted context omitted.

Probably all "slots" would be "occupied" and everybody gets the attacker's sent file, iiuc.

Or the attacker only needs to monitor the last free slot to see what shows up?

Seems to work both ways. Receive random file from unknown people or send chosen file to unknown people?

EDIT: was just explained in other comment by meejah, thanks! (https://news.ycombinator.com/item?id=14649727#14650551)

Re: Magic-Wormhole – Get things from one computer to another, safely

#59
post #50

So, basically, scp (with a 16-bit session key that has to be exchanged oob)?

Yeah, if you've already gotten a public key set up (and an account on the target machine), then scp is much easier and completely secure. magic-wormhole is more aimed at situations where you don't yet have that pubkey copied over. Or where your receipient doesn't want to give you an entire account just to receive a single file.

In fact there's a mode (kinda experimental right now) to use magic-wormhole to transfer an ssh pubkey into the ~/.ssh/authorized_keys on a new account. Ideally your site admin should be able to give you access to a new machine with a wormhole code, instead of having you email them a pubkey.

Re: Magic-Wormhole – Get things from one computer to another, safely

#60
> Copying files with ssh/scp is fine, but requires previous arrangements and an account on the target machine, and how do you bootstrap the account?~

Assuming that you have openssh and rssh installed, you bootstrap like this: useradd -m -g users -s /usr/bin/rssh tmp passwd tmp edit /etc/rssh.conf and uncomment allowscp Share the password with the party you want to exchange data with. Make sure your ports are open.

See: https://serverfault.com/questions/197545/can-non-login-accou...

The use case I see for wormhole is if you're working purely in the python ecosystem. That's it.

You're free to disagree of course, but I prefer ssh, since it's peer-to-peer end-to-end encrypted, and extends to cover other use cases much more easily (rsync, VNC, etc.).

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