Adding a new contact / key exchange

[Rpe23]

The first patch of the page "adding a contact" is online. The detailed methods will follow soon.

[thechauffeur]

What @Rpe23 meant is this wiki page. @Qabel/developer please review this page and ask yourself if this is the way a basic "browse" (i.e. establishing contact to someone) component can look like.

[thechauffeur]

My review:

• IMHO the described offline contact establishment is fairly simple and straightforward.
• The term "browse" might be misleading for the whole thing.
  • Maybe we want a real browse component to browse for people but without loosing the anonymity. If so that is definitely not included in the BETA.
• Some sort of establishing contact to someone is needed in BETA. IMHO this should be without the need of an additional "browse" server. Examples:
  • Encoding the public key and drop URL in a QR code.
    • Maybe only the fingerprint and getting the key elsewhere
  • Having the proposed JSON on some server which can be downloaded by the Qabel client but not a distinct browse server. Example:
    • Any pastebin like service
    • Basically any HTTP server to retrieve this JSON from when knowing the URL).

One question to the proposed JSON. How does it help providing the fingerprint together with the data itself? More general, how to verify the correctness of the information in such JSON?

[cburkert]

I reviewed the description and found some shortcomings.
The description does not represent the latest state of our discussion, if I'm not much mistaken.

The current proposal has the following shortcomings:

• fetched contact information is not authenticated
• server is not protected against directory attacks. Contact information is storage as plain text on the server.
• using a drop message to send back contact information does not work, because drop messages from unknown senders are discarded.

@Rpe23 maybe we can discuss this face-to-face on a meeting day?

[thechauffeur]

Bump.

[schulze]

I still don't know if Wulf is on Github.

Some remarks about requirements:

• We do need to transmit a public key and probably a Drop URL (if that can't be computed from the public key)
• Do we want to transmit an authoritative name, or can users invent their own local names for their contacts? (What is "a name"? In general that's always a hard question.)
• I think people expect that the BETA will have some interface for remote key exchanges. We need to think about how we want to handle this. Using SafeSlinger and a telefone line would maybe be an option. We could also use one of the established low-level PAKE protocol (SPAKE or EKE). There are certainly solutions we can use out there already.

[schulze]

Forgot to mention: There is also Pond's PANDA protocol that might be interesting for Qabel.

[mr-gosh]

I don't know if this possible - but the textsecure protocoll also implements some kinde of forward secrecy into the key exchange... https://whispersystems.org/blog/asynchronous-security/

[mr-gosh]

@schulze I think wulf is involved now...