Wir möchten ein Plugin in Auftrag geben, das private, verschlüsselte Nachrichten zwischen Endnutzern ermöglicht.
Dieses Plugin existiert mittlerweile und wird offiziell unterstützt. Weitere Informationen finden Sie unter: Discourse Encrypt (deprecated)
Derzeit gibt es im Internet nur sehr wenige Möglichkeiten für sichere, private und ausführliche Kommunikation. Die bestehenden Werkzeuge sind oft sehr kompliziert und erfordern extrem hohe technische Kenntnisse. Daher wird die Mehrheit der „privaten
Cool, yes, this will be open source under the MIT license, with an additional full license assignment to Discourse.
Regarding browser support, we want to make sure it works on every platform: Chrome + Safari is a minimum (so it works on iPhone / Android / Desktop), but my preference is that we hit Firefox as well. Edge is in the nice-to-have and IE11 is in the I don’t really care department, especially if it is missing crypto stuff.
Not for the initial version. Maybe for version 2 or 3, a PM between 20 users should absolutely work for V1.
Yes this is fine as an option. Basically would disallow PM to users that don’t have encryption enabled (but still allow admins to PM them unconditionally). We would need to think this through, but I don’t want to add this to the scope of the spec quite yet.
Thanks i’m obligated to sample an arbitrarily acceptable number of our PMs and reading people’s intimate conversations if only skimming is not only something I don’t want to do it takes time I haven’t got.
a PM between 20 users should absolutely work for V1.
That’s group chat in my context (Forgot where I am ) and will be fine. I’d expect strong support from our lot.
Keep in mind with this plugin it is technically impossible for you to read members private conversations provided they have a reasonably strong passphrase.
They are encrypted in the database and only decrypted client side. You would have to add a code exploit to your server for you to be able to swing reading encrypted PMs. Longer term (in v3 / v4) this code exploit would result in a giant red flag on the screen for people who install the “confirm my encrypted discourse conversations have not been exploited” browser plugin.
This is fascinating. It would be refreshing to do something really technically challenging. But, at least for me, the cost / benefit of taking the time to master (assuming, optimistically, that I could) all the relevant pieces doesn’t make sense right now.
That said, I just did a little reading on cryptography and have a few questions / thoughts:
Am I correct in understanding that you would need to generate a new conversation key every time you added or removed a member from the PM?
You would need some protection or warning against using other plugins as well. I can imagine a scenario in which you install this plugin, then someone writes another plugin that exposes or stores the entered text in some way before it is encrypted.
Wouldn’t you need to also only allow this feature on sites that force https? From the article you linked.
You can’t simply send a single Javascript file over SSL/TLS. You have to send all the page content over SSL/TLS. Otherwise, attackers will hijack the crypto code using the least-secure connection that builds the page.
Otherwise, in addition to the issue of the server sending malicious javascript you could also have the issue of ‘hijacking’.
Searchable semantic encryption is possible (by no means do I mean to imply that I understand the description in that paper). I assume you’re excluding it as the cost / benefit isn’t worth it, at least for the MVP.
The encrypted conversation key does not need to change on add. All members of the conversation have a copy of the decrypted conversation key. So to add a member you would encrypt this conversation key using the “invitee” public key and teach the server about that.
Technically it would be correct to amend the conversation key if you are removing members from a conversation, but we can wait on v2 for that. Cause it would be a very expensive operation from the client side, entire conversation would have to be re-encrypted, or complex multi conversation key systems need to be built.
Yes, the long term V3 / V4 goal here is to have a whitelist of JS integrity hashes stored in a browser extension. That is really the only way a client can know 100% that the “server is not messing with stuff”. However for V1 we trust the server and server operator not to be malicious.
Yes, if SSL is off all bets are off. We do not expect this feature to even remotely work if SSL is off.
Yes search is off the cards for now cause it is just going to be too hard to get right for the MVP.
Maybe, not against leaning on existing standards, but I suspect the Discourse integration work here is going to be enormous regardless.
Signed up to comment on this because I’m curious on the implementation as a developer myself.
I’m personally no cryptography pro, so forgive me if these are silly questions.
Would it not be viable to encrypt the message on the server-side using the public keys of people currently in the conversation, in this case?
Essentially I guess this would lead to a double layer of encryption - the data is encrypted client-side for true E2E encryption as described with the conversation key, and then encrypted on the way out by the server to only the public keys active in the conversation. At that point, removing a member from the conversation would mean any future messages wouldn’t be decryptable by them.
I’m not too sure on the security implications of nested encryption like that, however.
My second question is how well this would work cross-device? Does it require a private key on the device, or is that handled by the passphrase encrypted private key being stored?
Interesting idea the “double” encrypting. It does though add more responsibility to the server and a lot of this is about removing responsibility from the server so I am not sure it is a great idea protocol wise.
Cross device is handled by retrieving the encrypted private key from the server and decrypting using the key phrase.
Longer term we can introduce more “security” modes with a super strict one when say the server never even stores the private key encrypted (like say 1 password), but short term this is out of scope.
Those are not silly questions at all! If you want to dig deeper, I highly recommend Dan Boneh’s courses on Coursera.org.
This depends a lot on the particularities of the system you use. Check out double DES (i.e. vulnerable to meet-in-the-middle) and triple DES.
Let’s say Eve used to be a part of a group discussion with Alice and Bob. Even if Alice or Bob kick Eve out she will still have the conversation key and theoretically, she could intercept the messages before they get to the server and decrypt them.
If the conversation key gets compromised, the safest approach is to revoke it and use a new one for new messages. Ideally, you’d probably want to re-encrypt the old messages.
That makes sense to me, thanks for the explanation! (@sam too)
So adding or removing users from the conversation would involve decrypting everything client-side, revoking the conversation key and generating a new one, then re-encrypting messages before sending to the server?
Plus encrypting the new conversation key with the user passphrase and storing it.
I’ve been talking to my wife about this feature. While this may raise an eyebrow at mealtime conversation in our family, she’s a security engineer for Thales eSecurity.
She’s of the opinion that the Specification needs some use cases with bad actors and how the system should respond. For example: Malicious Admin, Malicious SysOps.
This would then give rise to a security statement that could be presented to users of the system.
I would love it if your wife or anyone interested in this problem at her work would pop by and give feedback.
@dan has made tremendous progress here, I am testing v1 with him this week.
To answer your specific question of bad sys admins. Overall if you can commandeer the web site and deliver malicious payloads our current v1 can not offer privacy. This is by design.
Our plans for v3/v4 is to have a browser plugin that validates every single JavaScript file on the page matches a particular hash in the whitelist. That way if you would be running this plugin you would be able to disallow unrecognized JS payloads.
Overall the underlying design means that passwords can not be fished out after the fact even if the server is malicious, but it can trick the client if it wishes to decrypt arbitrary payloads. Native browser plugins or a more refined web standard longer term will help eliminate this
Dieses Plugin existiert mittlerweile und wird offiziell unterstützt. Weitere Informationen finden Sie unter: Discourse Encrypt (deprecated)
) and will be fine. I’d expect strong support from our lot.
