[noise] Replacing TLS with noise

[Trevor Perrin]

On Wed, Dec 28, 2016 at 11:08 PM, Scratch <scratch.net at gmail.com> wrote:
>
> I'm looking into implementing a secure transport layer for communication
> between micro services. I don't want TLS because I don't need x.509 and all
> that stuff. I know that there's a proposal for TLS 1.3 to have a"keys only"
> mode, but it's still not accepted and i'm not sure it will get into
> standard. Keys are perfectly enough for me. But I also don't want to invent
> a bicycle here and use as much already invented things as possible.


The spec mentions a "length field" and a "type field" which you could
use for some minimal framing.  Basically, before each handshake
message, you could include:
 - 1-byte type (zero by default)
 - 2-byte length

The type byte can be changed for new versions of your protocol, or if
your handshake has alternative messages (like Noise Pipes).

After the handshake, you no longer need the type byte, so you can just
include the 2-byte length before each transport message.

You can make different decisions if your application has a different
approach to framing.  For example, WhatsApp embeds Noise fields within
XML, but it's not publicly documented.  WireGuard is adding extra
padding for alignment reasons.

You'll also need to make choices about handshake pattern, and crypto functions.

Definitely feel free to discuss these on list, it's been awhile since
we worked through a new application of Noise. It's always useful to
get another perspective, see what the confusing points are, etc..

Trevor