Nikos Mavrogiannopoulos <n...@redhat.com> writes: > How does this ties with crypto policies? libkrb5 is already under > crypto policies and has these ciphers disabled by default. Is this > change about removing them from the code or removing them from the > capabilities of the KDC which is not covered by crypto policies? > >> == User Experience == >> >> Ideally no change! Worst case some users will see krb5 produce error >> messages about bad enctypes not being able to be used (has no >> enctype, could not fullfill enctype, etc.). These pains are the >> feeling of the world grinding forward security-wise. > > I guess there will be different experience in client side where these > are already disabled by default in fedora, and in server side which > they are not.
To address I think both your questions: the defaults we set matter a lot less than we think they do. I observe plenty of machines running single-DES in the wild - despite this being permitted at no level of crypto-policies. This is obviously not the fault of crypto-policies in any way; users have explicitly chosen to route around the system's notion of "permitted" - and not without reason, in many cases. The two biggest culprits for this (beyond general legacy infrastructure) are Active Directory and AFS. Active Directory uses RC4 (crypto-policies LEGACY) as an interop cipher; this is why it's not actually removed in this change. AFS has been using single-DES (for interop) for quite some time. AFS does support more modern cryptography, but its adoption is far from universal. But I think the biggest takeaway here is that requiring users to perform additional configuration in order to hurt themselves won't actually stop them all from hurting themselves - especially not in the age of automation. Maybe it would have been more effective if we'd followed the 2009 `allow_weak_crypto` designation with a 2010 removal or some threat thereof. Hard for me to know; in 2009 I was busy being an obnoxious teenager. Thanks, --Robbie
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