Re: Bug in 1.5.1 KDC is session key selection

Andreas:

That is a bug in OpenAFS that has been fixed in OpenAFS.
Heimdal already fixed its bug and 1.5 is performing the selection
correctly in the absence of a specific request by the application.
Heimdal should not be issuing session keys with the weakest key type
when the application is requesting that the KDC use its best judgment.

Jeffrey Altman

On 1/19/2012 3:08 AM, Andreas Haupt wrote:
> Hi Nico, Jeffrey,
> 
> well, I'm not really an expert here. This is what Andrew Deason wrote on
> the OpenAFS mailing list some time ago:
> 
> ---
> klog doesn't specify the enc type (for any code path, as far as I can
> tell). It appears to work if I set des-cbc-crc with
> krb5_get_init_creds_opt_set_etype_list, but shouldn't the kdc be
> restricted to the enctypes that actually exist for the princ, though, or
> am I misunderstanding something here?
> ---
> 
> The whole thread is archived here:
> https://lists.openafs.org/pipermail/openafs-info/2011-October/036935.html
> 
> So, klog.krb5 of the OpenAFS master branch has been fixed (tested with
> version 1.7.4). But even the latest stable versions of the 1.4 and 1.6
> trees don't have it (yet?).
> 
> To my understanding Heimdal 1.2.1 used the strongest enctype for the
> session key from the list of available keys in the db during the AS
> request. For the afs principal this is a des-cbc-... enctype. Heimdal
> 1.5 selects aes256-cts-hmac-sha1-96 which the buggy klog.krb5 versions
> don't expect. If I could tell Heimdal to use a specific des-cbc- enctype
> for all operations concerning the afs principal, this would restore the
> former behaviour (to my understanding ...).
> 
> Cheers & thanks
> Andreas
> 
> On Wed, 2012-01-18 at 11:59 -0600, Nico Williams wrote:
>> What etype list should be assumed when the client sends an empty one?
>>
>> I'm guessing that for TGS exchanges that should be {<ticket's session
>> key>, des-cbc-crc, des-cbc-md5}.
>>
>> For AS it'd be {<enctypes available for pre-auth for the given client
>> principal>}.
>>
>> But I need to know.
>>
>> Nico
>> --
>

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