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content:tech:dna [28/05/2013 18:07] (current)
Andrew Bettison created
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 +====== Distributed Numbering Architechure (DNA) ======
 +The Distributed Numbering Architecture (DNA) is a necessary component of a distributed mesh telephone network that must function without any kind of infrastructure (such as known and reachable directory servers), for example in post-disaster or remote areas.
 +The problem in such situations is that even though people may have a [[mesh network]] connection with nearby devices, most people only know the regular telephone number of other people they wish to call.  Without a central directory that maps [[DID|phone numbers]] to [[SID|mesh network addresses]], how can the mesh be used to call a well known phone number?
 +The solution arrived at by [[:content:about]] is:
 +  * each person uses the [[Serval Mesh]] to enter their own, well known phone number, thereby "claiming" it on the mesh
 +  * anybody can claim any number on the mesh
 +  * to call a number, [[Serval Mesh]] broadcasts a DNA LOOKUP request to all nearby devices
 +  * the [[MDP]] broadcast mechanism on each device propagates the request (with as few duplicates or missing packets as possible) to all devices in a recursive fashion, as far as the TTL will permit
 +  * any device receiving the request checks its own claimed phone number, and if it matches, sends a DNA REPLY
 +  * the originating device collects all DNA REPLY responses and displays them to the user, who can choose which one to call
 +  * to assist this task, a **Name** can optionally be entered when claiming a phone number, and the DNA REPLY will contain the Name which will be displayed to the caller
 +==== Vulnerabilities ====
 +The DNA mechanism for resolving phone numbers is open to abuse by people claiming a phone number in order to impersonate the true "owner" of that number.  [[DID verification]] provides a way to record every authentic DNA REPLY so that imposters can be automatically excluded once the real owner of a number has been successfully contacted.
 +The DNA mechanism can be subverted by a man in the middle (MitM) attack.  [[SID verification]] provides a mechanism to detect a MitM which is almost impossibly hard to defeat.