Re: [radext] BoF request for IETF 115

[Alexander Clouter <[e-mail]>]

On Fri, 23 Sep 2022, at 21:38, Peter Deacon wrote:
>>
>> My concern is that the "shared secrets" used in today's RADIUS 
>> deployments often have little entropy, leaving them open to 
>> password-guessing attacks. So some additional thinking may be required 
>> here.
>
> Recommend using PAKE like the old TLS-SRP instead of TLS-PSK for password 
> based secrets.

Someone did try to graft PAKE into TLS but it ran out of steam[1]. Should this be a blocker to the SRADIUS draft?

That draft though did lead me to DH-PSK[2] but also Hybrid Public Key Encryption which states the same problem of how to handle low entropy keys[3]. There though the problem is the low cost of doing brute force, which mixing in (somehow with magic) a step similar to PBKDF2 might help buy the user more time to notice an attack and rotate keys.

Trying to make bullet proof an environment where someone wants to use their pets name as a PSK is probably a battle we are going to lose. In fairness, it is also a choice the user made for reasons that make sense to them and their local environment...it may not be correct but I am not sure there is anything anyone can do there.

Cheers

[1] https://datatracker.ietf.org/doc/html/draft-barnes-tls-pake
[2] https://datatracker.ietf.org/doc/html/rfc9257#section-4.2
[3] https://datatracker.ietf.org/doc/html/rfc9180#section-9.5