webwormhole

Peer authenticated WebRTC.

BSD-3-CLAUSE License

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THIS PROJECT IS STILL IN EARLY DEVELOPMENT IT USES EXPERIMENTAL CRYPTOGRAPHIC LIBRARIES AND IT HAS NOT HAD ANY KIND OF SECURITY OR CRYPTOGRAPHY REVIEW THIS SOFTWARE MIGHT BE BROKEN AND UNSAFE

https://xkcd.com/949/

WebWormhole creates ephemeral pipes between computers to send files or other data. Try it at https://webwormhole.io or on the command line.

On one computer the tool generates a one-time code:

$ cat hello.txt
hello, world
$ ww send hello.txt
east-pep-aloe

On another use the code to establish a connection:

$ ww receive east-pep-aloe
$ cat hello.txt
hello, world

To install the command line tool:

$ go install webwormhole.io/cmd/ww@latest

This requires Go 1.13 or newer.

To run the signalling server you need to compile the WebAssembly files first.

$ make wasm
$ ww server -https= -http=localhost:8000

To package the browser extension for Firefox or Chrome:

$ make webwormhole-ext.zip

WebWormhole is inspired by and uses a model very similar to that of Magic Wormhole.

https://github.com/warner/magic-wormhole

It differs in that it uses WebRTC to make its connections. This allows us to make use of WebRTC's NAT traversal tricks, as well as the fact that it can be used in browsers. The exchange of session descriptions (offers and answers) is protected by PAKE (we use CPace) and a generated random password, similar to Magic Wormhole. The session descriptions include the fingerprints of the DTLS certificates that WebRTC uses to secure its communications.

The author operates the signalling server at webwormhole.io, its alias wrmhl.link, and a relay server. These are free to use but come with no SLAs or any guarantees of uptime. They facilitate establishing connections between peers, but do not handle any transferred data in cleartext.

The protocol does not need to trust the signalling server to maintain the confidentiality of the files transferred. However, the convenience of using the web client directly on webwormhole.io comes at the cost of having to trust the code it serves. If the server is ever compromised it can be used inject malicious code that undermines the security of the client. To mitigate this, you can have more control over which version of the client you run by using the command line client or the browser extension. The extension is identical to the web client, but packaged for Chrome and Firefox, loads no remote code, and requires no permissions:

https://addons.mozilla.org/firefox/addon/webwormhole/
https://chrome.google.com/webstore/detail/jhombkhjanncdalcbcahinpjoacaiidn

Unless otherwise noted, the source files in this repository are distributed under the BSD-style license found in the LICENSE file.

Frequently asked questions

Is it compatible with magic-wormhole?

It is not. Maybe one day.

This project started as a UI for magic-wormhole, but drifted
away when I wanted to experiment with the PAKE used, the
protocol, and the word lists.

Why CPace and not another PAKE algorithm?

CPace and PAKE2 were the finalists for CFRG PAKE selection
process (https://github.com/cfrg/pake-selection), so it was
going to be one of the two.

CPace (https://tools.ietf.org/id/draft-haase-cpace-01.html)
looked nice and simple to implement, and there wasn't a
CPace Go package at the time, so it was a good opportunity
and a learning exercise to write one. I ended up nerd-sniping
Filippo instead and he beat me to write filippo.io/cpace.

Why not the PGP word list?

The PGP word list (https://en.wikipedia.org/wiki/PGP_word_list)
is quite good as far as unambiguity goes. However, a few
word combinations do make some unsavoury phrases. I switched
to a word list that is more agreeable.

Also, it would be nice to experiment with localised word
lists.

Don't you have to trust the web server anyway? What's the point of the PAKE?

Yes and no. The application itself, because of the PAKE,
does not need to trust the signalling server. You can install
the command line tool, the browser extension, or host the
web application's files yourself and not have to trust the
signalling server at all. There's also a mobile app version
in the works.

The web version hosted on webwormhole.io exists as a middle
ground between convenience and security. Like any other
website you visit, you do have to trust it's not running
any malicious code in your browser.