My take (I doubt this exists, and won't use chat until it does) -
Privacy against whom?
Privacy against all parties not participating in an exchange. Also, I will not use an app that uploads my contacts. This suggests that contacts are added manually, probably using an email address as an identifier, with mutual authorisation.
What is your threat model?
Information disclosure, spoofing, tampering and non-repudiation. The threat tree might include elevation of privilege. Denial of service is also important, in that I want it to use decentralised servers - if one goes down (or is taken down) another server picks up the load. New servers should be easy to add by anyone.
Side note - servers are preferable to me, so that messages get through when one or more parties in an exchange are offline.
What platforms must be supported?
All the platforms my contacts use, so Windows, Windows RT, and Windows Phone; OSX and iOS; Android; Linux. A nice-to-have fall-back is a browser-based client.
What level of technical knowledge do your contacts have?
Comments
My take (I doubt this exists, and won't use chat until it does) -
Privacy against whom?
Privacy against all parties not participating in an exchange. Also, I will not use an app that uploads my contacts. This suggests that contacts are added manually, probably using an email address as an identifier, with mutual authorisation.
What is your threat model?
Information disclosure, spoofing, tampering and non-repudiation. The threat tree might include elevation of privilege. Denial of service is also important, in that I want it to use decentralised servers - if one goes down (or is taken down) another server picks up the load. New servers should be easy to add by anyone.
Side note - servers are preferable to me, so that messages get through when one or more parties in an exchange are offline.
What platforms must be supported?
All the platforms my contacts use, so Windows, Windows RT, and Windows Phone; OSX and iOS; Android; Linux. A nice-to-have fall-back is a browser-based client.
What level of technical knowledge do your contacts have?
Enough to install the app, register and log in.