Re: [babel] [Babel-users] key rotation take #2

Juliusz Chroboczek <jch@irif.fr> Fri, 14 December 2018 16:51 UTC

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Date: Fri, 14 Dec 2018 17:51:31 +0100
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From: Juliusz Chroboczek <jch@irif.fr>
To: Dave Taht <dave@taht.net>
Cc: babel@ietf.org, babel-users@lists.alioth.debian.org
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Subject: Re: [babel] [Babel-users] key rotation take #2
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> This is the present babel conf file format:

> key id key1 type sha1 value deadbeefdeadbeefdeadbeefdeadbeefdeadbeef
> key id key2 type sha1 value dea2f0d01a57b0071057a11da7adeadbeeffffff
> interface enp7s0 unicast false hmac key1
> interface wg1 hmac key2

Right.  It currently cannot be updated dynamically, but the plan is that
it will at some point before HMAC get merged into mainline.

> so we invent a new keyword "serial".

> a key rollover is initiated by adding a new key with the same name and a
> larger serial number than the old one.

I don't understand what problem you're trying to solve.

You're happily HMACing your packets:

  key id key1 type sha1 value ...
  interface wlan0 hmac key1

At some point, you decide to start using a new key:

  key id key2 type sha1 value ...
  interface wlan0 hmac key1 hmac key2

You deploy the new key on all routers, then you delete the old key:

  interface wlan0 hmac key2

Why do you need a serial number?

-- Juliusz