Oct 11

Cryptographic Invitation Protocols

For a while now, I’ve been noodling around with a cryptographically-secure "invitation protocol" of sorts. I want something that can start with Alice sending an Invitation Message to Bob, and end with fully secure bidirectional communication.

The use cases I have so far are:

  • secure file-transfer tools, as a browser plugin or standalone application. The program would have an address-book, each entry would have an "Inbox" for that person, you would send them a file by drag-and-dropping it onto the Inbox. This invitation protocol would be used to populate the address book.
  • secure communication tools, like Petmail or an encrypted email/IM client, in which you want to add address-book entries so you can later exchange messages with the right correspondent.
  • Tahoe grid membership tools: you would use an Invitation to securely add another person’s client/server node to your grid, maintaining enough information to perform Accounting and server-selection properly.

but there are lots of others. Most applications with any sort of social component need a way to add "buddies" or correspondents. There are plenty of centralized systems (like IM networks, where the namespace is controlled by a single company), and a handful of insecure decentralized systems (like email addresses). I want this protocol for secure decentralized systems, in which the primary identifier for each participant is a public key of some sort.

Read on if you’re interested in cryptographic protocols..

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