On Wed, Sep 27, 2017 at 07:57:43PM +0800, Harald Welte wrote:
> For TMSI allocation, my "cryptographic gut feeling"[tm] is that something
> like rand() or any other pseudo-random generator of significantly large
> period is sufficient *if* it is seeded by a non-predictable value.  So
> something like seeding with getrandom() result should be fine?

Also matches my gut feeling there. Might also make sense to periodically
re-seed from /dev/urandom / getrandom(), like every 100 TMSIs, or based on a
timeout might be easier to implement.

> For long-term stable key (Ki/Op) generation for provisioning SIM cards +
> populating a HLR, I would certainly opt for using stronger randomness
> sources.  However, I don't think we actually implement that anywhere, do
> we?

what does openssh use for public/private keypair generation?

> What do you guys think?  Is there somebody on this list more
> cryptographically qualified to give us proper guidance?  If you know
> somebody skilled who might want to help but is not on this list, would
> you invite them to join this discussion?

I don't count myself as one of them, help is still appreciated.

~N

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