Provisioning arrangements for secnet - consultation
ijackson at chiark.greenend.org.uk
Wed Aug 24 15:12:27 BST 2016
Ian Jackson writes ("Provisioning arrangements for secnet - consultation"):
> I am starting by collecting requirements `user stories' . I will
> reply to this message with a couple of my own. Please do likewise,
> posting to sgo-software-discuss.
User story: Key rollover
Ian is running secnet and has been using the new provisioning
arrangements for 6 months or so. Ian does nothing.
Ian's secnet instances decide that Ian's keys are rather old. His
secnet nodes automatically generate new keypars, automatically
re-enrol them in the relevant vpn(s), and automatically start using
The new keys are automatically distributed throughout all the
relevant vpn(s). Ian's peer nodes pick up the new keys
After a suitable period, the old keys are de-provisioned, and
automatically de-authorised. Now, any attacker who has compromised
one of the old keys has no ability to do anything bad.
There is no interruption to service.
User story: Algorithm upgrade
Some time later, a version of secnet is released which support a new
ECC-based public key algorithm suite.
Ian upgrades one of his nodes, xenophobe, with `dpkg -i'. He does
xenophobe's secnet tools generate a new ECDSA keypair, and enrol it
in the SGO VPN. The new ECDSA keypair is distributed to all the
sites on the SGO VPN that support it, and to Ian's other secnet
Ian's un-upgraded nodes keep using the old RSA keys and keep working.
But Clare has also upgraded secnet on her laptop (which was earlier
enrolled as a mobile node with xenophobe). Clare does nothing else.
Clare's laptop receives the new ECDSA keypair and starts using the
new ECC cryptography when talking to xenophobe.
Despite the fact that both Clare's laptop, and xenophobe, still have
RSA keys, an attacker who compromises those RSA keys (or the
corresponding DH group) is unable to attack the traffic between
Clare's laptop and xenophobe.
User story: Algorithm retirement
Five years later: almost everyone has upgraded. A new version of
secnet is released which no longer generates RSA keys by default.
New installations are not compatible with un-upgraded sites, but do
not have to generate or distribute RSA keys.
Ten years later: RSA support is removed from secnet. As sites are
upgraded, they lose the ability to communicate with un-upgraded
sites. The RSA keys are dropped from the provisioning databases,
within the key rollover period if not before.
All of this happens without secnet node administrators having to do
anything other than install the new version of secnet.
Ian Jackson <ijackson at chiark.greenend.org.uk> These opinions are my own.
If I emailed you from an address @fyvzl.net or @evade.org.uk, that is
a private address which bypasses my fierce spamfilter.
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